Essentials for Survival

The human excretory system helps to eliminate waste and toxins from the body.

This involves regulating various physiological parameters, such as temperature, pH, hydration, and the concentration of ions and nutrients within the body, to ensure optimal functioning and survival. This system is built around numerous main organs, each with its own structure and function. The liver is a crucial excretory organ that processes waste via detoxification and bile synthesis. The skin, which is frequently ignored as an excretory organ, aids in waste elimination via sweat while also providing sensory protection. The kidneys are responsible for filtering blood, reabsorbing vital nutrients, and excreting waste via urine. Meanwhile, the lungs support gas exchange by exhaling CO₂and controlling blood pH. However, faults within this complex system can cause serious health problems, making knowledge of these processes critical. This overview will look at the form and function of these organs, the mechanisms involved in waste disposal, and the abnormalities that can occur within the human excretory system.

KEY IDEAS

• Metabolism: It plays a crucial role in metabolic processes, regulating blood glucose levels by storing and releasing glycogen as needed, thus impacting energy metabolism.

• Detoxification: The liver metabolises toxins and drugs, converting them into less harmful substances.

• Urinary Tract Infections (UTIs): Infections can affect various parts of the urinary system, causing pain and urgency and potentially leading to kidney damage if untreated.

• Blood is filtered in the nephrons, where waste products and excess substances are separated from essential nutrients and water in the process called filtration.

• When sweat reaches the surface of our skin, it evaporates, which means it turns from liquid into gas and goes into the air.

• Blood tests that measure bilirubin levels can help diagnose liver diseases, anaemia, and other conditions affecting the bile ducts or liver function.

1. Why is it important for the body to get rid of waste instead of holding onto everything we eat and drink?

2. Imagine if your house didn’t have a trash bin, what might happen? How is this similar to what would happen in your body without excretion?

The human body has a group of organs that work together to remove waste and keep us healthy. These organs make up the excretory system: the liver, skin, lungs, large intestine, and kidneys. Each of these organs has a special role in removing waste:

• Liver: Processes and breaks down harmful substances, turning them into safer forms to be removed.

• Skin: Releases waste through sweat, which also helps cool us down.

• Lungs: Remove carbon dioxide when we breathe out (exhale).

• Large Intestine: Removes undigested food as stool.

• Kidneys: Filter out extra water and salts, turning them into urine.

Each of these organs are different, but together they work like a team to make sure our body stays clean and balanced. They get help from other parts of the body, like the circulatory system (which moves blood around to carry waste to these organs), the nervous system (which sends messages to tell these organs what to do), and the endocrine system (which releases hormones to keep everything in balance).

By working together, these systems help keep the body’s internal environment stable, which is called homeostasis. Homeostasis is like having the perfect balance in the body so everything works as it should.

Activity 1.1 Understanding Excretion

You have been provided with a diagram of the human excretory system during the open STEM activity in your school. Observe the diagram for a few minutes and discuss the different organs with friends.

Figure 2.1: Human Urinary System

Questions

1. What does the diagram represent?

2. Which excretory organ can you find in the diagram

3. How will the diagram help you to explain excretion to your friends?

4. Create key ideas that show metabolic waste, and the organs involved.

5. After creating your ideas, each group is to present your work to the class so that all will learn together. Keep up the great work!

Compare your findings with the following key points:

• Excretion is a biological process in which an organism eliminates metabolic waste from its body. The body eliminates metabolic by- products and harmful substances and regulates bodily water levels, pH, and ionic concentration of blood fluid.

• Excretion is an extremely important mechanism in the human body.

Excretion removes all that we consume from our bodies. After eating, the body absorbs all the useful substances and nutrients. The remaining substances are waste, which may be harmful to the body, and is expelled using the body’s excretory organs. The human excretory system consists of a pair of kidneys, a pair of ureters, a urinary bladder, and a urethra.

These are the main organs that constitute the human excretory system.

Apart from them, some other organs help in the excretion as well. They are skin, liver, and lungs.

Activity 2: Identification of Excretory Organs and Their Functions A group of SHS 2 learners is participating in a science fair project titled “The Great Excretion Challenge.” Their task is to create a presentation of the excretory organs: liver, kidneys, lungs, skin, large intestine, and their products.

In this project, they encounter “Mr. Waste,” a character representing various waste products that need to be expelled from the body. Mr. Waste provides hints about himself and his friends, urea, excess salt, bile pigments, excess water, and carbon dioxide.

A B C D Questions Use the table above; showing the excretory organs to help you express your ideas about the key questions. Write down your answers in your notebook.

1. Can you match each waste product with its corresponding organ?

2. What happens if a person’s kidneys stop working?

3. Which other organ is not represented?

You have just completed an amazing journey through the “Great Excretion”. See

Table 2.1 for the key points you should know about the excretory organs and their waste products

Table 2.1: Excretory organs and metabolic waste substances Excretory organs Metabolic wastes Skin Your skin helps to remove waste through sweat. Sweat contains water, urea, lactic acid, and salts. When you sweat, you not only cool down your body but also get rid of these wastes.

Kidney The kidneys are like filters for your blood. They remove excess salts, water, and nitrogenous waste (such as urea) by making urine. This is how your body gets rid of waste products that build up in your blood.

Lungs Your lungs help you breathe out waste in the form of carbon dioxide and water vapor. When you exhale, your body gets rid of carbon dioxide, which is a waste product created when your cells use oxygen to produce energy.

Liver The liver has many jobs, and one of them is breaking down old red blood cells. It produces bile pigments as a waste product from this process. These pigments eventually leave your body with stool.

Nitrogenous Waste: This includes substances like ammonia, uric acid, urea, and trimethylamine oxide.

The liver helps change ammonia (which is toxic) into urea, which is then removed by the kidneys Large intestine The large intestine helps remove solid waste. It also deals with waste from the liver, such as bilirubin, which gives stool its colour.

Activity 1.3 Exploring Skin Structure and Function

1. Research the three layers of skin: epidermis, dermis, and subcutaneous layer, focusing on their structure and functions.

2. Use online resources such as videos and other resources to learn about the roles of each layer in protection, sensation, and temperature regulation.

3. How does each layer contribute to overall skin health?

4. Create a summary table detailing the structure and functions of each layer.

5. Present your findings to your peers or family.

Let us examine one of the excretory organs, the skin!

Structure of the Skin

The skin has three main layers and each does a different role (see Figure 2.2)

• Epidermis (Top layer): This is the thin, outer layer that you can see. It protects us from things in the environment, such as bacteria and sunlight.

The epidermis also makes melanin, the pigment that gives our skin its colour.

• Dermis (Middle layer): This is the thicker layer under the epidermis. It holds sweat glands (that produce sweat to help cool us down), hair roots, and blood vessels. It’s responsible for making sure our skin feels things like touch, pain, and temperature.

• Hypodermis (or Subcutaneous layer): This is the bottom layer of the skin, made mostly of fat. It acts like a cushion, protecting our muscles and bones, and helps keep us warm by insulating our body.

Figure 2.2: Structure of the skin Processes Involved in Excretion by The Skin Think of these questions as you read the processes involved in excretion by the skin

1. How do the different types of sweat glands contribute to the body’s cooling system and waste removal process?

2. What role does evaporation play in temperature regulation, and how does it relate to the effectiveness of the excretion process through sweat?

3. Explain how understanding skin structure can help in real-life situations (e.g., skincare, health).

Remember the skin plays an important role in getting rid of waste from our bodies through a process called excretion. Here are the key processes involved:

1. Sweat Production: Sweat is made by special glands called sweat glands located in the middle layer of the skin (the dermis). There are two types of sweat glands:

a. Eccrine glands produce a watery sweat all over the body to help cool us down.

b. Apocrine glands, found in places like our armpits and groin, create a thicker sweat that has a stronger smell.

2. Diffusion and Filtration: When sweat is produced, waste products from our blood, such as urea and salt, move out through the sweat glands. This process is called diffusion, where these waste materials pass from the blood into the sweat. The sweat glands also filter out extra salts and electrolytes to keep our body’s fluid levels balanced.

3. Evaporation: When sweat reaches the surface of our skin, it evaporates, which means it turns from liquid into gas and goes into the air. This evaporation cools our skin and body down, helping to regulate our temperature, especially when we are exercising.

Question: Write down your answer in your notebook.

1. In what ways do the functions of the skin, such as protection, thermoregulation, sensation, excretion, and vitamin D synthesis, contribute to overall health and homeostasis in the human body?

Table 2.2: Functions of the parts of the skin.

Parts Description

Epidermis Waterproof Barrier:

The skin creates a waterproof layer that stops too much water from leaving the body. This is important because, without this barrier, our body could lose a lot of water just by being exposed to the air. The skin helps keep just the right amount of water inside, which is essential for staying healthy and hydrated.

Protection from Germs:

The skin also works like a shield that protects the body from harmful germs such as bacteria, viruses, fungi, and other microscopic invaders, called pathogens. These germs can make us sick, so the skin acts as a wall to stop them from getting inside our body. It’s like wearing a suit of armour that keeps the body safe from things that could harm it.

Dermis The skin is strong and flexible, which is important for protecting our body. Strength in the skin comes from a special protein called collagen, which makes it tough and able to resist tearing. This strength helps protect our muscles, bones, and other organs underneath.

The skin can stretch and then go back to its normal shape due to another protein in the skin called elastin.

Elasticity allows the skin to stretch when we move, grow, or gain weight and then return to its original shape.

Hypodermis The skin helps keep the body warm by insulating it. This means it conserves heat and helps keep our body temperature stable, even when it’s cold outside. This insulation helps our body work at the right temperature to stay healthy.

Hair follicle The skin is responsible for producing and growing hair through tiny structures called hair follicles. These follicles, found in the skin’s deeper layers, create hair by adding cells to the root, pushing the hair upward as it grows. Hair can help protect the skin and keep the body warm.

Parts Description

Sweat glands Sweat glands are like tiny faucets in our skin that release sweat when we’re hot. The sweat cools our body down as it evaporates, helping us stay at a comfortable temperature.

Sebaceous gland These glands make an oily substance called sebum. Sebum keeps our skin and hair soft and prevents them from drying out or cracking. It acts like natural lotion that protects our skin.

Capillaries Capillaries are tiny blood vessels in our skin. They bring oxygen and nutrients to skin cells to keep them healthy.

Capillaries also help control our body temperature by expanding to release heat or narrowing to keep us warm.

Nerves The nerves in our skin let us feel sensations like touch, pain, heat, cold, and pressure. They’re like messengers, sending signals to our brain so we can react to our surroundings, like pulling away from something hot.

Stratum corneum This is the tough, outer layer of the skin. It protects us from cuts, harmful chemicals, and germs. It also forms a waterproof barrier that keeps water inside our body and stops water from getting in when we swim or wash our hands.

Melanocytes These are special cells in our skin that make melanin, which gives our skin its colour. Melanin also protects us from the sun’s UV rays, which can damage our skin.

Adipose or fat tissue This layer under the skin acts like padding, protecting our muscles and bones from bumps and injuries. It also helps insulate us, keeping us warm, and stores energy for our body to use when needed.

Question: Write down your answers in your notebook.

1. Can you think of specific medications that are significantly affected by first-pass metabolism in this organ?

What are functions of the Skin?

1. Protection: The skin serves as a physical barrier against pathogens, chemicals, and environmental damage, providing essential protection to underlying tissues.

2. Thermoregulation: It helps regulate body temperature through sweat production and vasodilation or vasoconstriction of blood vessels.

3. Sensation: The skin contains sensory receptors that detect pressure, temperature, pain, and touch, aiding in environmental interaction.

4. Excretion: Through sweat glands, the skin excretes waste products such as urea, salts, and water, playing a role in managing body fluids and electrolyte balance.

5. Vitamin D Synthesis: The skin plays a critical role in making vitamin D upon exposure to sunlight, important for calcium absorption and bone health.

Activity 2.4 Skin Model

What you need: Cardboard paper (different colours if possible, or white paper to colour in), scissors, markers or coloured pencils, glue and labels or small slips of paper What to do:

1. Cut a thin strip of cardboard paper to represent the epidermis. This is the outermost layer of the skin and acts as a protective barrier.

2. Cut a thicker strip of cardboard paper to represent the dermis layer. This part will show where things like sweat glands, hair follicles, and blood vessels are found.

3. Use a thicker piece of cardboard paper for the subcutaneous layer. This layer contains fat tissue, which insulates the body.

4. Place the epidermis layer on top, the dermis layer in the middle, and the subcutaneous layer at the bottom.

5. Glue each layer in place, stacked from top to bottom, to create a layered model of the skin.

6. Use small cut-out shapes or draw directly on the dermis layer to show structures:

a. Hair follicles: Draw or add small cardboard pieces for hair follicles.

b. Sweat glands: Use a spiral shape or small circles to represent sweat glands.

c. Blood vessels: Use thin strips of red and blue paper or markers to show blood vessels.

d. In the subcutaneous layer, you can add circles or shapes to represent fat tissue.

ACTIVITY 2.5 Excretory Organs and Waste Products

Here are multiple-choice questions focusing on excretory organs and their waste products, the functions of the skin, and the processes of removing waste from the human body by the skin. Circle the correct answer as you read.

1. Which of the following is a primary excretory organ responsible for the removal of urea from the body?

A. Kidney B. Liver

C. Lungs D. Skin

2. Which of the following is NOT a function of the skin?

A. Protection against pathogens B. Sensation C. Synthesis of vitamin C D. Temperature regulation

3. What waste products are mainly excreted through the skin by sweating?

A. Glucose and cholesterol B. Oxygen and carbon dioxide C. Proteins and lipids D. Urea and salts

4. Which type of gland in the skin is primarily responsible for the excretion of waste products?

A. Eccrine and apocrine glands B. Follicle glands C. Mammary glands D. Sebaceous glands

5. How do the three layers of the skin contribute to its overall function?

A. The epidermis absorbs nutrients, the dermis prevents dehydration, and the hypodermis facilitates respiration.

B. The epidermis acts as a barrier, the dermis contains blood vessels and nerves for sensation, and the hypodermis stores fat and anchors the skin.

C. The epidermis provides insulation, the dermis provides the structural integrity, and the hypodermis prevents water loss.

D. The epidermis regulates temperature, the dermis produces sweat, and the hypodermis protects against diseases.

Liver The liver is the largest solid organ in the body. It is located below the lungs in the upper right-hand side of the abdomen. It is reddish-brown and shaped approximately like a cone or a wedge. The small end is above the spleen and stomach, and the large end is above the small intestine. — See Figure 2.3

Figure 2.3: Structure of the Liver

The liver consists of four lobes. These are the (larger) right and left lobes and the smaller caudate quadrate lobes. The left and right lobes are divided by the falciform ligament which is sickle shaped. This connects the liver to the abdominal wall.

The lobes of the liver can be divided further into eight segments which consist of thousands of lobules (small lobes). Each of these lobules has a duct flowing towards the common hepatic duct, which drains bile from the liver. — See Figure 2.4

Figure 2.4: Anterior and Posterior Views of the Liver There are eight hepatic segments. If the patient is supine (laying on their back facing up), and the liver is reflected along its inferior border towards the diaphragm, the segments would be numbered anticlockwise around the porta hepatis. — See

Figure 2.5

Figure 2.5: Hepatic segments of the liver The left lobe of the liver is located on the left side of the body. This will be the patient’s left, just under the diaphragm. It is generally smaller and more flattened and wedge-shaped than the right lobe. Its upper surface is slightly convex and is moulded on to the diaphragm.

The right lobe of the liver: This is six times the size of the left lobe. It is located predominantly in the right hypochondrium and extends into the epigastrium. It is separated from the left lobe by the falciform ligament on its superior surface and from the caudate lobe by the right sagittal fissure.

Question: Write down your answers in your notebook.

1. How would you create a model of the liver, using suitable materials?

Activity 2.6 How to Create a Liver Model

What you need: Styrofoam block (preferably one large enough to cut into the shape of a liver), red and brown paint or markers, small piece of yellow clay or foam (for the gallbladder), small tubes, straws, or pipe cleaners (to represent blood vessels) and glue What to do:

1. Cut the Styrofoam block into a roughly triangular shape with rounded edges to resemble the shape of the liver.

2. Smooth any rough edges to make it look more realistic.

3. Paint the Styrofoam brown or dark red and allow the paint to dry completely.

4. Use a small piece of yellow clay or foam to form a small oval shape, representing the gallbladder.

5. Attach the gallbladder to the bottom of the liver model on the right side.

Glue it in place to keep it secure.

6. Insert short pieces of straw into the Styrofoam to represent blood vessels (the hepatic artery, portal vein, and hepatic vein).

7. Colour these vessels different colours if possible (e.g., red for the artery, blue for the veins) to distinguish them.

8. Present the model to your peers or family explaining the functions of each part.

Functions of the liver

1. Production of bile, which lowers the surface tension of fats for digestion.

2. Production of blood protein called albumin, which prevents leakage of fluids from the bloodstream and transports hormones, enzymes and vitamins in the body.

3. Removal of toxins and other harmful substances from the blood.

4. Regulation of amino acids to healthy levels.

5. Initiation of clotting of blood, by producing bile to aid vitamin K.

6. Removal of bacteria from the blood to prevent or minimise infections.

7. Storage of vitamins A, D, E and K as well as minerals such as iron and copper.

8. Processing of glucose by removing excess glucose (sugar) from the bloodstream which it stores as glycogen. As needed, it can convert glycogen back into glucose.

9. Production of cholesterol and special proteins to help carry fats through the body.

10. Processing of haemoglobin, for storing its iron content.

Processes Involved in Excretion by the Liver

The liver plays a vital role in excretion by eliminating various waste products and toxins from the body. Below is a table (see Table 2.3) of the key processes involved in this function.

Table 2.3: Excretion by the liver Process Explanation Breakdown of ammonia Ammonia is a toxic by-product of protein metabolism that occurs throughout the body, especially in the muscles. The liver utilises the urea cycle to convert ammonia into a less toxic substance called urea. Urea is much easier for the kidneys to eliminate through urine.

Elimination of

bilirubin Bilirubin is a yellowish pigment produced during the normal breakdown of red blood cells. The liver captures bilirubin and conjugates it with other molecules, making it water-soluble, and then secretes it into bile.

Process Explanation

Detoxification The enzymes of the liver break down or modify harmful substances such as drugs, alcohol and environmental toxins into less harmful forms that can be excreted through bile or urine.

Elimination of excess hormones and other molecules The liver regulates the levels of various hormones, by breaking them down or excreting them in bile.

Additionally, it removes excess molecules like bilirubin and cholesterol from the bloodstream.

Contribution to blood purification By undertaking excretory processes, the liver plays a crucial role in filtering and purifying the blood by removing waste products, toxins, and excess substances. This maintains a healthy internal environment for the body to function properly.

Activity 2.7 Dissection of the Liver to Identify its Parts (Video) Research and watch a video of how to dissect a liver. While watching the video, answer the following questions in your notebooks:

1. Name a minimum of five items used in the activity.

2. Write down a minimum of five steps and order what you see being done in the activity.

3. Identify a minimum of six parts of the liver exposed by the dissection.

4. Describe how the parts you have identified are connected one to another.

5. List a minimum of two precautions that were taken in the video.

6. List a minimum of three safety measures adopted in the video.

Activity 2.8 Scenario About the Kidney

Read the scenario carefully.

Imagine your body as a busy city, and your kidneys are two important waste management plants working hard to keep everything running smoothly.

As the day begins, your kidneys start their main job: filtering blood.

The blood enters the kidney through the renal arteries, just like trucks delivering garbage to a recycling centre.

Each kidney has about a million tiny workers called Nephrons, ready to get to work.

As the blood flows through the nephrons, they begin filtering out waste.

They remove things your body doesn’t need, such as urea, extra salt, and water.

This is like sorting through trash to keep the good stuff and throwing away what is not needed. The important things, such as sugar and some water, go back into the blood.

Those that are not important turn into urine, which travels from the kidney to the bladder.

Questions: Put down your answers on paper as you read and discuss the scenario.

1. Why is the work of the kidney very important?

2. What happens to the waste that has not been used by the body after the blood has been filtered?

3. How do important things such as sugar and some water, after filtering out waste, get into the blood?

Structure and Function of the Kidney

• The kidneys are two bean-shaped organs located in the back of the body, just under the rib cage. They are positioned on either side of the spine, with the right kidney typically sitting lower than the left due to the position of the liver.

• Each kidney has a small gland called the adrenal gland sitting on top of it.

These glands help the body manage stress and other functions. The kidneys’ main job is to clean the blood. They filter out waste and extra water to make urine, which is then removed from the body.

• Internally, the kidney has two main areas: the renal cortex on the outside and the renal medulla on the inside. In the medulla, there are 5-8 triangle- shaped parts called renal pyramids that make urine. These pyramids are separated by sections of connective tissue called renal columns.

• Each pyramid has a tip called a renal papilla, which drains the urine it creates into a small collecting area called a minor calyx. Several minor calyces join together to form a larger area called a major calyx.

• All the major calyces connect to a central space called the renal pelvis, which then leads to the ureter.

• The ureter is the tube that carries urine from the kidney to the bladder. This structure helps the kidney efficiently collect and drain urine from the body.

— See Figure 2.6 Our kidneys use a lot of oxygen to do their work, about 25% of the oxygen we breathe in. Oxygen helps kidney cells create energy to keep filtering blood. This energy is in a form called ATP (adenosine triphosphate), which the body uses to perform many tasks.

Kidneys are essential because they help remove waste and keep our blood clean and balanced.

Figure 2.6: Internal structure of the kidney Questions: Write down your answers in your notebook.

1. What anatomical structures provide protection to the kidney?

2. Name structures found in the renal helium.

Functions of the Different Parts of the Kidney

Table 2.4: The functions of each part of the kidney Parts Function Renal Pelvis Collects urine from different parts of the kidney and funnels it into the ureter to leave the body.

Renal Vein Carries cleaned blood (without oxygen) from the kidney back into the bloodstream.

Renal Artery Brings oxygen-rich blood to the kidney so it can be filtered.

Renal Pyramid

Moves urine from the renal cortex to the renal pelvis.

Renal Medulla

Contains parts of the nephron that help concentrate urine and keep the body’s water balanced.

Ureter A tube that carries urine from the kidney to the bladder.

Capsule The kidney’s tough outer layer that protects it and helps it keep its shape.

Minor Calyx Collects urine from each renal pyramid.

Major Calyx Channels urine from minor calyces to the renal pelvis.

Hilum An entry and exit area for blood vessels, nerves, and urine pathways.

Renal Column

Contains blood vessels and tubules that support the nephrons.

Renal Cortex The outer part of the kidney where blood is filtered through tiny units called nephrons.

How Blood Flow Through the Kidney

• The kidneys get a lot of blood because they need to filter and clean it. About 25% of the blood pumped by the heart goes to the kidneys. Blood enters the kidneys through renal arteries, which are large blood vessels coming from the heart’s main artery, the aorta. These arteries go into the kidney at a part called the renal hilum.

• Inside each kidney, the renal arteries split into smaller arteries that move through the kidney, eventually reaching tiny tubes in the cortex (outer part of the kidney). The smallest of these arteries are called afferent arterioles, which bring blood to a special capillary bed called the glomerulus. The glomerulus is a key part of the kidney’s nephrons (tiny units that filter blood). Each kidney has about 1.3 million nephrons, which work together to clean the blood.

• After blood is filtered, the clean blood leaves the kidneys through renal veins that connect to the inferior vena cava (a large vein that returns blood to the heart). Any waste and extra water form a liquid called filtrate. This filtrate goes through the collecting ducts, then into the minor and major calyces, and finally to the renal pelvis, where it’s carried to the bladder by the ureters as urine. — See figure 2.7

Figure 2.7: Flow of blood in the kidney Structure of the Nephron The nephron is the kidney’s functional unit, with over a million in each kidney, mostly in the outer layer (renal cortex).

Each nephron filters blood through the renal corpuscle, processes the filtered liquid into urine in the renal tubule, and receives blood through a capillary network. — See Figure 2.8

Figure 2.8: Structure of the nephron Functions of the Parts of Nephron

Table 2.5: Functions of the parts of nephron Parts Function Renal Corpuscle (Glomerulus + Bowman’s Capsule) The renal corpuscle is the starting point for making urine.

It filters the blood by pulling out water, glucose, ions, and waste, creating a fluid that will later become urine.

Proximal Convoluted

Tubule (PCT) This part, close to Bowman’s Capsule, reabsorbs most of the filtered water, glucose, and nutrients from the fluid back into the blood. This reabsorption is important to keep the body from losing too much water and valuable substances.

Loop of Henle This U-shaped loop enters the kidney’s medulla and helps concentrate urine. The descending part allows water to leave, while the ascending part pumps out salts. This setup helps the body hold onto water when it needs to.

Parts Function

Distal Convoluted

Tubule (DCT) The DCT fine-tunes urine concentration by absorbing more sodium and water back into the blood and balancing acids and minerals like potassium. This keeps our body’s salt and pH levels balanced.

Renal Filtration

Activity 2.9 Renal filtration What you need: Two clear plastic bottles, coffee filters or fine cloth, gravel (small pebbles), sand, activated charcoal, water, food colouring (to simulate waste), measuring cups and container or beaker.

What to do:

1. Cut the bottoms off two plastic bottles to create funnels.

2. Place a coffee filter or fine cloth at the bottom of each bottle.

3. In the first bottle, layer the gravel, then sand, and finally activated charcoal. This will simulate the filtration layers of the kidneys.

4. In a separate container, mix water with a few drops of food coloring to represent blood that contains waste products.

5. Pour the coloured water slowly into the top of the first bottle (the one with the filtration layers).

6. Observe how the water passes through the layers and collects in the bottom of the bottle.

7. Place a container under the second bottle to catch the filtered water.

8. After the water has filtered through, observe the clarity of the water in the container.

Questions: Record your answers in your notepad.

1. What changes did you notice in the water after it passed through the filtration layers?

2. How does this experiment relate to how kidneys filter blood in our bodies?

3. Why do you think it’s important for the kidneys to filter out waste?

Urine Formation

Urine formation in the kidneys involves three main steps: filtration, reabsorption, and secretion.

Let us explore the steps!

A. Filtration:

• This process starts in a part of the nephron called the renal corpuscle, which includes the glomerulus (a bundle of tiny blood vessels) and Bowman’s capsule (a cup-like structure).

• Blood enters the glomerulus under high pressure, which pushes water, ions, glucose, and waste (like urea) out of the blood and into Bowman’s capsule, forming the initial fluid called glomerular filtrate.

B. Reabsorption:

• After filtration, this filtrate flows into the renal tubule.

• The tubule reabsorbs essential nutrients like ions, glucose, and water back into the blood through nearby capillaries, making sure the body doesn’t lose useful substances.

C. Secretion:

• During this final stage, waste ions and hydrogen ions move from the capillaries into the renal tubule, where they combine with the remaining filtrate to form urine.

• The urine then flows through the collecting duct, exits the kidney through the renal pelvis, travels down the ureter, and is stored in the bladder.

Processes Involved in Excretion of Waste by the

Lungs What happens when we breathe in and out? Let us begin with a simple activity!

Activity 2.10 Blow up the Balloon Experiment What you need: balloons What to do: Take a deep breath and blow up the balloon.

Questions: Write down your answers in your notepad.

1. What happened to the balloon after blowing it up?

2. What did you put inside the balloon?

3. Why is it important to get rid of carbon dioxide?

4. What would happen if we could not remove carbon dioxide from our bodies?

Now, let us explore how the lungs get rid of metabolic waste from the body!

What Happens During Breathing?

When you breathe in (inhale), your lungs take in air that is rich in oxygen.

When you breathe out (exhale), your lungs push out air that contains carbon dioxide and a little bit of water vapour.

Activity 2.11 Demonstrate That Exhaled Air Contains Water Vapour What you need: Small mirrors (one for each learner or group) What to do: Breathe out gently onto the mirror, holding it close to their mouth.

Questions

1. Write your answers in your notebook. What happened to the surface of the mirror?

2. Why do we need oxygen?

Every cell in your body needs energy to function, like a car needs fuel. To get this energy, cells break down a type of sugar called glucose. To release energy from glucose, cells need oxygen. This process is called cellular respiration.

The formula looks like this: Glucose + Oxygen → Energy + Carbon Dioxide + Water What happens during cellular respiration?

When your cells use oxygen to produce energy, they also create two metabolic waste products: carbon dioxide (CO₂) and water vapour.

The energy produced is what keeps your body moving, thinking, and working.

The carbon dioxide and water are not needed, so they need to be removed from the body.

Activity 12: How Do the Lungs Remove Carbon Dioxide (CO₂) What to do: Research and watch videos online on how the lung removes metabolic waste.

Questions: Record your findings from the research in your notebook.

1. How does diffusion help in gaseous exchange in humans?

2. How do the lungs remove waste?

Inside your lungs, there are tiny air sacs called alveoli. These alveoli are surrounded by blood vessels (capillaries).

When you breathe in, the oxygen goes into the alveoli and then passes into the blood.

At the same time, carbon dioxide from the blood moves into the alveoli. This happens through a process called diffusion, where gases move from where there’s a lot of them (high concentration) to where there’s less (low concentration). — See Figure 2.9 Exhaling Waste Products After the carbon dioxide collects in the alveoli, it is pushed out of the body when you breathe out. This is how your body gets rid of carbon dioxide, a waste product.

Water vapor (a bit of moisture) also leaves your body when you exhale. This helps keep your body’s water balance in check.

Why is it important to get rid of carbon dioxide?

Getting rid of carbon dioxide is crucial because if it builds up in your body, it can make your blood too acidic, which is dangerous.

The removal of carbon dioxide and water vapor through breathing helps keep your body’s systems in balance and ensures your cells can keep making energy.

Figure 2.9: Human Respiratory System

Processes Involved in Excretion by the Large

Intestine Let us explore the processes involved in excretion by the large intestine.

Questions: Write down your answer in your notebook.

1. What happens to the leftover food that our body doesn’t need?

2. Why is it important for the large intestine to absorb water?

3. What would happen if the large intestine did not absorb water properly?

Activity 2.13 Excretion by the Large Intestine

What to do:

1. Research and watch videos online on how the large intestine removes metabolic waste.

2. Record your findings from the research in your notebook.

3. Answer these questions

a. How does the stool move in the large intestine?

b. How does osmosis help in absorption of water in the large intestine?

4. Share your findings with your peers or family members.

How does the large intestine get rid of waste product?

The large intestine’s role is to take the leftover material from the small intestine, absorb water and salts from it, and turn it into solid waste (stool). It then moves the stool to the rectum, where it is stored until you go to the bathroom to get rid of it. This process helps your body save water, stay balanced, and keep things moving smoothly. — See Figure 2.10

1. Receiving undigested material: After your food is digested in the small intestine, there are still some parts left that the body can’t use. This leftover material, called chyme, moves into the large intestine through a small opening called the ileocecal valve. The chyme contains substances such as fibre (which the body cannot digest), some water, and dead bacteria.

2. Water absorption: The main job of the large intestine is to absorb water from the chyme. The walls of the large intestine have special cells that take water out of the chyme, making the material thicker and turning it into a more solid form. This helps prevent the body from losing too much water.

3. Electrolyte balance: While absorbing water, the large intestine also takes in electrolytes (salts and minerals) from the chyme. These electrolytes, like sodium and potassium, are important for keeping the body balanced and helping it function properly.

4. Stool formation: As more water is absorbed, the leftover material becomes thicker and eventually forms stool (also known as faeces). Stool is made up of things like undigested food (such as fibre), dead cells from your intestines, mucus, and bacteria.

5. Mass movement and storage: The large intestine moves the stool slowly towards the end of the digestive system using muscle contractions. These movements are called mass movements. When the stool reaches the last part of the large intestine, called the rectum, it is stored there until it’s time to get rid of it.

6. Elimination (Defecation): When the stool reaches the rectum, it pushes against the walls, which makes you feel the need to go to the bathroom. The anal sphincter muscles (muscles at the end of the rectum) relax, and you use your abdominal muscles to push the stool out of your body through the anus. This is called defecation.

Figure 2.10: Human Large Intestine

Activity 2.14 Inhalation of Oxygen and Exhalation of Carbon Dioxide What you need: large plastic bottle (1-2 litre size), two small balloons, one large balloon (to represent the diaphragm), two drinking straws, tape or rubber bands and scissors What to do:

1. Cut off the bottom of the plastic bottle to create an open end. This will allow you to attach the “diaphragm” later.

2. Attach a balloon to the end of each straw. These balloons represent the lungs.

3. Use tape or rubber bands to secure the balloons tightly to the straws, making sure no air can escape.

4. Insert the two straws with the attached balloons through the neck of the bottle. These straws represent the trachea (windpipe) and bronchi leading to the lungs.

5. Use tape to seal the area around the neck of the bottle so that the straws are held in place.

6. Take the large balloon and cut it in half. Discard the top part and keep the bottom part (the rounded end).

7. Stretch this part over the open bottom of the plastic bottle. This will act as the diaphragm, which helps pull air in and push air out.

8. Pull down gently on the diaphragm (the stretched balloon at the bottom of the bottle).

9. Let the diaphragm go and gently push it upwards. The “lungs” will deflate as the air is pushed out.

Let us understand some disorders of the excretory system.

Questions: Write your answers in your notebook

1. What happens when a person eats contaminated food?

2. What happens when a person’s leg gets fractured?

Disorder A disorder is a problem or condition that affects how a part of the body works.

It means that something is not functioning properly. For example, when a person has a stomach disorder, it means their stomach is not working the way it should, which might cause them to feel sick, have pain, or have trouble digesting food.

Kidney disorders Perform Activity 2.15 for a better understanding of some kidney disorders.

Activity 2.15 Kidney Disorder (Kidney stones).

What you need: Two clear cups, a spoonful of salt or sugar, water and a stirrer.

What to do:

1. Fill one cup with a small amount of water and dissolve a spoonful of salt or sugar in it.

2. Keep adding more salt or sugar until it no longer dissolves. and you can see tiny crystals forming at the bottom.

Observation: Tiny crystals forming at the bottom.

Questions: Write your answers in your notebook

1. Did you get similar expected results? If not, what resulted to the error and how can it be corrected?

2. What will happen if you add more?

3. How does de-hydration affect the kidney function?

Brief explanation of the activity This is similar to how kidney stones form. When there is too much mineral and not enough water in the urine, the minerals start to stick together and form crystals, just like kidney stones in the kidneys.

Table 2.6: Disorders of the kidney Disorder Description Causes Symptoms Treatment/ Prevention Glomerulonephritis (GN) A condition where the tiny filters in the kidneys, called glomeruli, become swollen and irritated Swelling of glomeruli, the tiny filters in the kidneys by infections, problems with the immune system (when the body attacks itself by mistake) Blood in the urine, High blood pressure, Edema, protein in urine Severe cases require dialysis or kidney transplant.

Kidney stones A condition in which there is a build-up of certain minerals in the urine, like calcium and oxalate in the kidney.

Eating a lot of salty foods Not drinking enough water Blood in the urine, nausea and vomiting, severe pain in the lower back or side.

Surgery is required for stones, drinking lots of water can help flush them out, reduce severe intake of salt.

Disorder Description Causes Symptoms Treatment/

Prevention Acute Kidney Injury

(AKI) It is a sudden and quick loss of kidney function, meaning the kidneys can’t filter waste and extra water from the blood like they usually do.

Not having enough water in the body can harm the kidneys.

Losing a lot of blood can make it harder for kidneys to do their job.

Severe infections:

Less urine: They might not pee as much as usual.

Swelling in legs and ankles: Extra fluid in the body can cause parts of the body to swell.

Manage fluid intake.

Use diuretics and medicines: Doctors may give medicines to help the person pee more or to control the levels of important minerals like potassium in the blood.

Treat infections and avoid harmful medicines. Temporary dialysis: If the kidneys are not working well enough on their own, a machine (dialysis) might be used temporarily to clean the blood.

Disorder Description Causes Symptoms Treatment/

Prevention Polycystic

Kidney Disease

(PKD) A genetic disorder characterised by the growth of numerous cysts in the kidneys.

Genetic mutations High blood pressure, back or side pain, blood in urine, and frequent kidney infection Surgery to remove cysts, drinking plenty of water to prevent kidney stones.

- Treat kidney infections, dialysis or kidney transplant.

Skin disorders A skin disorder is a condition that changes how the skin looks, feels, or works.

It can make the skin look different, feel uncomfortable, or stop it from doing its job. Skin disorders can happen for many reasons, like allergies, infections, or even genetics, and they can be mild or more serious, depending on the type and cause

— see Table 2.7.

Table 2.7: Disorders of the skin Disorder Description Causes Symptoms Prevention/ treatment Acne Acne shows up as pimples, blackheads, or cysts when skin pores get clogged.

Hormones boost oil production, clogging pores, and allowing bacteria to grow. Stress, diet, and some medications can worsen it.

You might see pimples, blackheads, or painful lumps on the face, chest, back, or shoulders.

Cleanser and

topical creams can help. For severe cases, doctors may prescribe stronger medications.

A good skincare routine and healthy diet help manage it.

Eczema Eczema causes dry, itchy, red patches on the skin that may crack or blister Often due to genetics, allergies, and weak skin barriers.

Skin can be dry, itchy, and red, especially with exposure to stress or irritants.

Moisturisers soothe and protect, while creams help reduce itching and redness.

Severe cases may need stronger medications.

Disorder Description Causes Symptoms Prevention/

treatment Psoriasis This is an autoimmune condition that causes red, scaly patches.

The immune system mistakenly attacks the skin.

Red patches with white scales appear on the elbows, knees, and scalp.

Creams, light therapy, and medications can help reduce symptoms.

Skin Rashes

Red, irritated, or swollen areas on the skin.

Allergies, infections, heat, or contact with irritants like chemicals.

Itching, redness, bumps, and sometimes blisters.

Avoid irritants, apply soothing creams, keep skin clean, and use prescribed treatments for infections.

Atopic Dermatitis

A type of eczema that’s very itchy and often linked to allergies.

Like eczema, related to genetics and allergies.

Common on the face, hands, and feet. In babies, it may appear on the cheeks and scalp.

Moisturisers and creams for itching help, and avoiding triggers is essential.

Liver Disorders

Liver disorders are problems that prevent the liver from working as it should. The liver is an important organ that helps our body by cleaning out harmful substances (toxins), making proteins that our body needs, and producing substances for digesting food. When the liver doesn’t work properly, it can affect the whole body, because the liver’s job is to keep our body healthy and balanced. — See Table 2.8.

Table 2.8: Disorder of the liver Disorder Description Causes Symptoms Prevention/ treatment Hepatitis Hepatitis is an inflammation of the liver.

Viruses (hepatitis A, B, C), alcohol, drugs, autoimmune reactions.

Tiredness, yellowing of the skin and eyes (jaundice), nausea, stomach pain.

No cure for viral hepatitis, but vaccines can prevent hepatitis A and B. Hepatitis C can be treated with antiviral medication.

Liver cancer Liver cancer is a type of cancer that begins in the liver, primarily affecting liver cells.

Chronic hepatitis B or C infections, cirrhosis, or exposure to certain toxins.

Weight loss, upper stomach pain, yellowing of the skin, loss of appetite.

Surgery to remove cancerous parts, liver transplant, and protecting the liver from risk factors like hepatitis viruses and toxins.

Cirrhosis Cirrhosis is a late-stage liver disease characterised by the replacement of healthy liver tissue with scar tissue (fibrosis), which can severely impair the liver’s ability to function.

Long-term liver disease causes scarring (like chronic hepatitis or ALD).

Yellow skin, fluid buildup in the abdomen, fatigue, confusion.

Lifestyle changes and medications can help manage symptoms; a liver transplant may be needed in severe cases.

Disorder Description Causes Symptoms Prevention/ treatment Autoimmune Hepatitis Chronic liver disease in which the body’s immune system mistakenly attacks healthy liver cells, leading to inflammation and damage.

The immune system mistakenly attacks liver cells;

genetics may play a role.

Yellow skin, tiredness, loss of appetite, abdominal pain.

Immunosuppressant medications to help prevent immune system attacks on liver cells.

Non-Alcoholic Fatty Liver

Disease (NAFLD) Liver condition characterised by the accumulation of excess fat in liver cells, occurring in people who drink little to no alcohol Fat buildup in the liver is unrelated to alcohol.

Linked to obesity, diabetes, and high cholesterol.

Often none but can include tiredness or mild upper right abdominal pain.

Weight loss through healthy diet and exercise; managing conditions like diabetes.

Alcoholic Liver Disease

(ALD) This is a liver condition caused by prolonged heavy alcohol consumption, resulting in inflammation, fat buildup in the liver (steatosis), and, over time, severe scarring (fibrosis) or cirrhosis.

Long-term alcohol use damages liver cells, leading to fat buildup and scarring.

Fatigue, loss of appetite, yellow skin (jaundice), swelling in the legs.

The best prevention is to avoid or reduce alcohol. Complete abstinence from alcohol is essential for managing ALD.

Activity 2.16 Disorders of the Excretory Organs

What to do:

1. Familiarise yourselves with the different skin and liver disorders discussed in class. Make note of their symptoms, causes, and treatments.

2. One student will take on the role of the “patient.” The rest of the class will act as “doctors.”

3. The “patient” will describe one symptom they are experiencing (e.g., “I have a rash on my hand” or “I feel very tired and have jaundice.”).

4. The “doctors” will take turns asking one question at a time to determine which disorder the “patient” might have. Examples of questions include:

a. Is the rash itchy?

b. Have you consumed a lot of alcohol recently?

c. Do you have any other symptoms like fatigue or nausea?

5. Once the disorder is correctly identified, the “doctors” will take turns suggesting possible treatments or lifestyle changes for the “patient.” For

example, “You should avoid alcohol and see a doctor for further tests” for Alcoholic Liver Disease, or “Using moisturisers can help with your rash” for eczema.

6. After the disorder is identified and treatment is suggested, a new “patient” will come to the front with a different symptom. Repeat the process, ensuring different students take turns playing the roles of “patients” and “doctors.” Encourage and respect each other’s views.

Questions: Write down your answers in your notebook.

1. What happens to the “lungs” (balloons) when the diaphragm moves down?

2. Why do you think carbon dioxide needs to be removed from our body?

3. How does this activity help us understand the process of breathing?

1. The diagrams below represent the structures of the human body. Study them carefully and answer the questions that follow A B

a. Identify the diagram A and B

b. Name the Label the parts numbered 1,2,3 and 4

c. How does the skin regulate the body temperature?

d. How does the epidermis differ from the dermis in terms of structure and function?

e. What are the three main layers of the skin, and what are the primary functions of each layer?

2. Identify at least four parts of the liver.

3. Describe four functions of the liver.

4. How does the liver excrete waste from the body.

5. What is the outer layer of the kidney called?

a. Medulla

b. Cortex

c. Pelvis

d. Ureter

6. The nephron is a functional unit of the kidney. True or false

7. The _________ is the central cavity of the kidney where urine collects.

8. What are the two main functions of the kidneys?

9. Match the following parts of the kidney with their functions:

(a) Parts (b) Functions

Ureter stores Bladder filters blood Nephron transports urine to the bladder Renel medulla concentrate urine

10. Name the excretory products of the following excretory organs.

a) Lungs

b) Large intestine

11. How does the large intestine eliminate stool from the body?

12. Describe what happens when the following metabolic waste are not remove the body.

a) Faces (stool)

b) Carbon dioxide

The movement of air in humans is necessary for survival because it allows the respiratory system to provide critical oxygen to cells while also removing carbon dioxide, a byproduct of metabolism. Understanding the structure of the lungs, which include the trachea, bronchi, and alveoli, shows how effectively they facilitate gas exchange. Aerobic respiration, the mechanism by which cells convert glucose and oxygen into energy, is strongly dependent on proper lung function. However, smoking can have a serious impact on respiratory health, resulting in conditions such as asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. In this section, you will learn about the movement of air in humans and its importance, the structural components of the lungs, the process of aerobic respiration, and how smoke and common respiratory illnesses affect overall health. This exploration highlights the importance of maintaining respiratory health and encourages awareness and preventive measures against harmful environmental factors.

KEY IDEAS

1. Exhalation: Exhalation is the release of air from the lungs and is essential for maintaining respiratory function, occurring as a counterpart to inhalation.

2. Diaphragm and abdominal muscles: During exhalation, the diaphragm relaxes and moves upward, while the contraction of abdominal muscles helps push the diaphragm further upward, aiding in air expulsion.

3. Structure of the lungs: The lungs are vital respiratory organs consisting of two lobes (left and right), with essential components like the trachea, bronchi, alveoli, and pleura responsible for gas exchange.

4. Aerobic Respiration: This process involves using oxygen to convert glucose into energy, underscoring the importance of efficient lung function for energy production in cells.

5. Disorders: A disorder is any condition that deviates from normal functioning, affecting different facets of health and well-being, and varying in severity from mild to life-threatening.

6. Chronic Obstructive Pulmonary Disease (COPD): a progressive lung disorder characterised by breathing difficulties and other symptoms, highlighting the importance of respiratory health awareness.

Activity 3.1 Breathing Process

What to do: Breathe in and out. What you have just done is taking air in and out of the body.

Questions: Write your answers in your notepad.

1. Do you take time to think before you breathe?

2. Where does the air the go when you breathe in?

3. Where does the air you breathe out come from?

Breathing Breathing is the process of taking oxygen into the lungs from the atmosphere and taking out carbon dioxide from the lungs into the atmosphere. It is an essential bodily function that allows the body to take in oxygen and remove carbon dioxide from it.

Breathing involves air movement through the respiratory passages and structures to the lungs, where gas exchange occurs. Breathing in is also known as inhalation (inspiration) while breathing out is called exhalation (expiration). Inhalation introduces oxygen into the body while exhalation takes carbon dioxide out of it. Exchange of oxygen and carbon dioxide is vital for the body to function and produce energy. — See Figure 3.1.

Figure 3.1: Inhalation and Exhalation

Structures and Processes Involved in the

Movement of Air

Movement of air in humans involves the actions of structures and various processes. The structures and their functions are as follows:

• Pharyngeal Cavities: They are passages provided by the mouth and nose.

They are called oral and nasal passages respectively. Both passages warm and moisturise the incoming atmospheric air. The nasal passage is lined with hair cells that help to filter the air by eliminating dust particles, smoke and other colloidal substances from it. The nasal and oral passages are lined with mucous membranes which trap dust, bacteria and viruses from the air.

— See Figure 3.2.

Figure 3.2: Pharyngeal Cavities

• Trachea: A cartilaginous tube which connects the pharyngeal cavities to the lungs. It provides a pathway for air to enter and leave the lungs. It is lined with cilia which filters the incoming air further.

• Bronchi (one is bronchus): They are branches of the trachea which are embedded in the lungs. They provide a pathway for air to enter and leave the lungs.

• Bronchioles: They are numerous branches into which the bronchi divide extensively in the lung, forming a bronchial tree. They ensure that air is carried to every part of the lungs and removed from them as well. — See

Figure 3.3.

Figure 3.3: Structure of trachea, bronchi and bronchioles

• Alveoli: They are sac-like structures into which the bronchioles end. They effect gaseous exchange between bronchioles and the lungs. — See Figure 3.4.

Figure 3.4: Alveoli

Lungs: The lungs are the organs of respiration and make up a large part of the respiratory system. They are a paired cone shaped organ lying in the thoracic cavity, separated from each other by the heart and other structures in the area between them, called mediastinum.

The lungs are connected to the trachea at the upper side by the right and left bronchi.

On their lower surface, they are bordered by the diaphragm. The diaphragm is a flat, dome-shaped muscle located at the base of the lungs and thoracic cavity. The lungs are enclosed by layers called pleurae, which are attached to the mediastinum.

The inner layer, called visceral pleura, wraps around the lungs and is stuck so tightly to the lungs that it cannot be peeled off. The outer layer, called parietal pleura, lines the inside of the chest wall. There is a very thin space between the layers called the pleural space. A liquid, called pleural fluid, is in the pleural space.

The right lung is shorter and wider than the left lung, while the left lung occupies a smaller volume than the right lung. There is an indentation on the surface of the left lung called the cardiac notch. This allows space for the heart. The apex of the lung is the superior region, whereas the base is the inferior region. The lung has three surfaces namely the costal, mediastinal, and diaphragmatic surfaces. The costal surface borders the ribs, the mediastinal surface faces the midline while the diaphragmatic surface borders the diaphragm beneath it. — See Figure 3.5.

Figure 3.5: Human lungs Pathway of Air into The Body

Figure 3.6: Pathway for Inhaled Air

Activity 3.2 Concept Map for Movement of Air in The Body What to do:

1. Create a concept map for the direction of flow of air into the lungs. — See Figure 3.6

2. Explain why when someone’s head is cut off, he or she cannot survive but can survive when the hand is cut off.

What happens to inhaled or inspired air in the body?

Each air sac or alveolus (plural is alveoli) is surrounded by a rich network of fine blood vessels (capillaries). The oxygen in inhaled air passes across the thin lining of the air sacs into the blood vessels. This is known as diffusion. The oxygen in the blood is then carried around the body in the bloodstream, reaching every cell where it is used to power every reaction and process that needs oxygen to break down food to release energy for use by the body. This is known as aerobic respiration.

After the red blood cell has released oxygen in the cells of tissues and organs, it picks up carbon dioxide, which is a major excretory product of aerobic respiration, and transports it to the lungs. Carbon dioxide is expelled from the body through the lungs during the process of exhalation or expiration. — See Figures 3.7 to 3.8.

Question: Why are the alveoli able to carry out gas exchange effectively? Write your answer in your notebook.

Figure 3.7: Alveoli Surrounded by Blood Capillaries

Figure 3.8: Gaseous exchange in alveolus

Activity 3.3 Making a Human Lung Model

What we need: A plastic bottle, some straws, a few balloons, hot glue, a pair of scissors and utility knife.

What to do:

1. Punch a hole in the bottom portion of the bottle with scissors.

2. Cut the bottle into two pieces horizontally with the scissors.

3. Insert one of the scissor blades into the incision that you made so that half of the scissors is inside of the bottle.

4. Hold the bottle firmly in your non-dominant hand, and cut all the way around the side of the bottle with your scissors so that you end up with two halves—one half with the bottle cap and one half with the base.

5. Discard the bottom half of the plastic bottle.

6. Use the utility knife to cut an opening in the bottle cap.

7. Test the bottle cap by trying to fit a plastic straw inside.

8. Cut a plastic straw into three equal lengths with the scissors.

9. Slide the pointed edges of two pieces of straw into the bottom of a larger straw.

10. Glue the junction where the three straws meet, with a hot glue gun.

11. Add hot glue to the inside lip of two balloons and put them on the straws.

12. Slide the open end of the larger straw through the bottle cap.

13. Cut another balloon near the neck with the scissors.

14. Glue the inner neck of the cut balloon and slide it over the bottom of the bottle. This acts as the diaphragm. — See Figures 3.9 to 3.10

Figure 3.9: A Model of Human Lung Figure 3.10: Inhalation and Exhalation Safety Precautions

1. Keep your hand away from the blade.

2. Use a newer, sharper blade so that you don’t have to apply as much pressure.

3. Allow all glued parts to dry well.

Mechanism of Inhalation (Inspiration) in Humans

Perform Activity 3.4 to gain a deeper understanding of inhalation!

Activity 3.4 Breathing Mechanisms

What you need: the model made in activity 3.3 What to do:

1. Pull on the skin of the balloon at the bottom and release.

2. Record your observation as you pull on the balloon at the bottom and release it Questions: Write down your answer in your notebook.

1. What is the difference between inhalation and exhalation?

2. What happens to the diaphragm during inhalation and exhalation processes?

Inhalation (inspiration) Mechanism

• External intercostal muscles contract while internal intercostal muscles relax.

• This causes the rib cage and sternum to move upward and outward.

• The diaphragm contracts, moves down and flattens.

• The volume of the thoracic cavity increases.

• Air pressure in the thoracic cavity becomes lower than atmospheric pressure.

• Air flows from the atmosphere where there is higher pressure into the thoracic cavity where there is lower pressure. — See Figure 3.11.

Figure 3.11: Inhalation (inspiration)

Mechanism of Exhalation (expiration) in Humans

Carbon dioxide is expelled from the body by the following respiratory movements and processes in the order as follows:

• External intercostal muscles relax while internal intercostal muscles contract.

• This causes the rib cage and sternum to move down and inward.

• The diaphragm relaxes and moves up to its original dome shape.

• The volume of the thoracic cavity decreases.

• Air pressure in the thoracic cavity becomes higher than atmospheric pressure.

• Air, rich in carbon dioxide, flows from the thoracic cavity where there is higher pressure into the atmosphere where there is lower pressure. — See

Figure 3.12.

Figure 3.12: Exhalation (expiration)

Differences Between Inhalation and Exhalation

Table 3.1: Differences between inhalation and exhalation Aspect Inhalation Exhalation Muscles involved Diaphragm contracts and moves down, external intercostal muscles contract, iInternal intercostal muscles relax.

Diaphragm relaxes and moves up, external intercostal muscles relax, internal intercostal muscles contract.

Volume change Thoracic cavity expands (increases in width and length) Thoracic cavity decreases in width and length.

Aspect Inhalation Exhalation

Volume of

lung Increases Decreases Air pressure in lungs Decreases Increases Air movement From atmosphere into lungs From lungs into atmosphere Energy needs Active process, needs energy (ATP) Passive process, needs no energy (ATP) Breathing cycle Initiation Completion Gas involved Oxygen Carbon dioxide Structural movement Ribs and sternum move up and outward Ribs and sternum move down and inward Importance of Air Movement in Humans Imagine what would happen to the human body if no air flowed in it. The movement of air in humans is vital for maintaining proper respiratory functions and overall health. The site of exchange is in the alveoli. The movement of air in the human body comes with the following benefits:

1. Oxygen supply:

a. Inhalation brings oxygen-rich air into the lungs, which is absorbed into the bloodstream.

b. Oxygen is essential for cellular respiration, providing the energy needed for the body’s various functions.

2. Carbon dioxide removal:

a. Exhalation removes carbon dioxide from the body, a waste product of cellular respiration.

b. Efficient air movement ensures that carbon dioxide levels in the body are kept within a healthy range, preventing build-up and potential health issues.

3. Respiratory homeostasis:

a. Air movement helps maintain the body’s balance of gases (oxygen and carbon dioxide), which is crucial for preserving the body’s pH and other physiological parameters.

b. Disruptions in air movement can lead to respiratory disorders, such as hypoxia (low oxygen levels) or hypercapnia (high carbon dioxide levels).

4. Lung function:

a. Regular air movement helps to keep the lungs healthy and to function optimally.

b. It prevents the build-up of mucus and other respiratory secretions, which can impair lung function if not cleared.

5. Immune system support:

a. Air movement helps to filter and remove airborne pathogens, such as bacteria and viruses, from the respiratory system.

b. This protects the body from respiratory infections and supports the overall immune system.

6. Physical and mental well-being:

a. Efficient air movement improves physical performance by delivering more oxygen to the muscles.

b. It also reduces stress and anxiety by triggering the relaxation response associated with deeper and slower breathing patterns.

The use of lungs and on how cells use oxygen to convert glucose and other nutrients to produce energy carrier.

Activity 3.4 Watch a Video on The Respiratory System What to do:

1. Watch a short video, model or animation that explains the structure of the respiratory system.

2. Take notes on the key features and functions of each part.

3. Examine the lungs and their components, including the trachea, bronchi, bronchioles and alveoli along with the surrounding blood vessels

4. Create your own labelled illustration of the lungs, ensuring to include trachea, bronchus, bronchiole, lungs and alveolus.

5. Share your work with your peers or family members by discussing the structure, functions, and location of various lung components, and encourage your classmates to ask questions for further discussion.

6. Post your work on your social media platform to encourage others.

Questions: Write your answers in your notebook.

1. Which components of the respiratory system are supported by firm cartilage?

2. Which sections of the respiratory system show flexibility and elasticity?

3. Where in the respiratory system can you find goblet cells and cilia?

4. Explain the roles of alveoli, bronchioles, and cilia.

Respiratory system The lungs serve as the respiratory organs in our body, facilitating all gas exchange processes. Typically, humans possess a pair of lungs: the left and the right. They are responsible for inhaling oxygen (O₂) and exhaling carbon dioxide (CO₂).

The lungs are essential for delivering oxygen to our body, and without this vital function, survival would be impossible within a minute. The main components of the lungs include the trachea, alveoli, bronchi, and pleura.

The parts of the respiratory system made of firm cartilage include the trachea and primary bronchi. The trachea, or windpipe, has C-shaped rings of cartilage that keep it open while allowing some flexibility. The primary bronchi branch off from the trachea into the lungs and have similar cartilage support.

The flexible and elastic parts of the respiratory system are the bronchioles and alveoli. Bronchioles are smaller branches that lead to the alveoli, where gas exchange occurs. They can expand and contract thanks to smooth muscles and elastic fibres in their walls. Alveoli stretch when filled with air and recoil when we exhale, which helps with efficient gas exchange.

Goblet cells and cilia are found in the trachea and bronchi. Goblet cells produce mucus to trap dust and germs, while cilia are tiny hair-like structures that move the mucus upward to keep the airways clean. This process, known as mucociliary clearance, helps maintain respiratory health by preventing infections. — See

figure 3.13 and table 3.2

Figure 3.13: Respiratory System of Humans

Table 3.2: Functions of the parts of the respiratory system Parts Function Trachea The trachea, or windpipe, is a rigid tube that provides a clear airway for air to enter and exit the lungs. It is lined with ciliated mucous membranes that trap dust and debris, keeping the airway clean.

Bronchi The bronchi are the main air passages that branch off from the trachea into each lung. They further divide into smaller bronchi and play a crucial role in directing air to the lungs while also filtering and humidifying it.

Bronchioles Bronchioles are the smaller branches of the bronchi that lead to the alveoli. They regulate airflow to the alveoli through constriction and dilation and are lined with smooth muscle to control this process.

Parts Function

Nasal passages The nasal passages are responsible for filtering, warming, and humidifying incoming air. They contain mucous membranes and cilia that trap contaminants and provide a moist environment for air before it enters the lungs.

Alveoli Alveoli are tiny air sacs at the end of the bronchioles where gas exchange occurs. They are surrounded by capillaries, allowing oxygen to diffuse into the blood and carbon dioxide to diffuse out, making them essential for respiration.

Pharyngeal cavities The pharyngeal cavities (throat) serve as a passageway for both air and food. They play a role in directing air from the nasal passage to the larynx and eventually to the trachea while also aiding in swallowing.

Pleura It produces a lubricating fluid between the layers, allowing the lungs to smoothly expand and contract during breathing Diaphragm It plays a crucial role in breathing by contracting and relaxing. When the diaphragm contracts, it pulls the lungs downward, increasing the chest cavity volume, which creates a low-pressure area. Air rushes in to fill the lungs (inhalation). When the diaphragm relaxes, the chest cavity volume decreases, pushing air out of the lungs (exhalation) Questions: Record your answers in your notepad.

1. How does the structure of the trachea differ from that of the bronchi and bronchioles, and how do these differences impact their respective functions in the respiratory system?

2. Where are the lungs located in the body?

3. In what ways do you think the location of the lungs in the thoracic cavity influences their ability to function effectively during breathing?

Structure of the Lungs

The lungs are situated in the thoracic cavity, which is a protected space that allows for expansion and contraction during breathing without interference from other organs. This location, surrounded by the ribcage, provides structural support while allowing the diaphragm and intercostal muscles to efficiently change the volume of the thoracic cavity, facilitating airflow into the lungs. Additionally, being near the heart allows for the quick transport of oxygenated blood throughout the body. One specific feature is the alveoli, which are tiny air sacs that dramatically increase the surface area for gas exchange. Their thin walls allow for easy diffusion of oxygen into the blood and carbon dioxide out of the blood. The sheer number of alveoli in the lungs maximises this area, making gas exchange much more efficient. The trachea is a rigid tube supported by C-shaped cartilage rings, which keep it open and allow air to flow freely to the lungs. In contrast, the bronchi have similar cartilage but branch off into smaller bronchioles, which have more smooth muscle and less cartilage. This allows the bronchioles to constrict or dilate to regulate airflow. The increased flexibility in the bronchioles is important for controlling the amount of air that reaches the alveoli.

Activity 3.5 Try Questions

Let us briefly revise some of the concepts we have learnt so far. Below are some statements. You need to state whether they are true or false. These true or false questions can help assess your comprehension of the lung anatomy and associated features.

True or false?

Here are five true or false activity questions based on the provided information:

1. The tracheal walls are strengthened with specialized rings of cartilage known as tracheal cartilage to prevent collapse…

2. Goblet cells in the tracheal walls secrete mucus that helps to trap dust and pathogens…

3. The trachea is lined with ciliated cells that help to trap dust and pathogens further down the respiratory system…

4. The lungs are in the abdominal cavity and are not protected by the rib cage…

5. The terms “left lung” and “right lung” refer to the patient’s perspective, meaning the left lung is on the patient’s left side…

Activity 3.6 Aerobic Respiration Produces Carbon Dioxide

What you need: Tapes, Beakers, freshly prepared lime water, cardboards and straws.

What to do:

1. Take two test tubes containing equal volumes of freshly prepared lime water.

2. Plug each test tube with a cork fitted with straw.

3. Blow air into one test tube with the help of the straw while leaving the other test tube undisturbed.

4. Discuss your observations with friends or family member and write them in your notebook.

Safety precautions

1. Do not ingest the lime water.

2. Keep the neck of the test tubes tightly plugged.

3. Do not keep the lime water standing for too long before blowing exhaled air into one of them.

Table 3.3: Differences Between Breathing and Respiration

Aspect Breathing Respiration

Definition The physical procedure of inhaling and exhaling air The biochemical process of bringing out energy from food particles Process Includes the exchange of gases (O₂and CO₂) between the organism and the environment It involves chemical reactions, mainly oxidation of glucose, to produce energy.

Location Takes place in the respiratory organs (lungs, gills, etc.).

It takes place in the cells, specifically in the mitochondria.

Voluntary or

involuntary Partially voluntary (e.g., can hold breath) but mostly involuntary.

Completely involuntary;

controlled by cellular needs Aspect Breathing Respiration Purpose To bring Oxygen into the body and take away Carbon dioxide To make energy ATP (adenosine triphosphate) essential for cellular

activities.

Oxygen Involvement

Oxygen is inhaled into the lungs.

Oxygen is used to oxidise glucose in cells.

Carbon Dioxide Carbon dioxide is exhaled out of the lungs Carbon dioxide is produced as a waste product of cellular respiration Energy Requirement Does not produce energy but requires energy to function.

Produces energy in the form of ATP (adenosine triphosphate) Examples Breathing in humans involves the diaphragm and intercostal muscles Aerobic respiration, anaerobic respiration (e.g., fermentation).

Aerobic Respiration

The breakdown of organic food substances is a complex process involving many enzymes acting as catalysts. The energy released is in the form of ATP (adenosine triphosphate). Respiration is the breakdown of organic food substances in the living cells to release energy.

Aerobic respiration is the type of respiration which takes place in the presence of oxygen. A lot of energy is produced in this type of respiration. Carbon dioxide and water are produced as by-products. Aerobic respiration can be expressed as:

• C6H12O6 + 6O2 → 6CO2 + 6H₂O + energy

• Glucose + oxygen = carbon dioxide + water + energy Anaerobic respiration is the type of respiration which occurs in the absence of oxygen. A small amount of energy is produced. It occurs in yeast, with alcohol and carbon dioxide produced as a byproduct. Anaerobic respiration is also known as alcohol fermentation.

Importance of Aerobic Respiration

1. Energy Production: The primary role of aerobic respiration is to generate ATP, the main energy source for cells. ATP fuels important cellular functions, including muscle contraction, protein synthesis, and cell division.

This process is highly efficient, yielding 36-38 ATP molecules from a single glucose molecule.

2. Production of Carbon Dioxide and Water: Aerobic respiration transforms glucose and oxygen into carbon dioxide and water, which are then expelled from the body as waste. This process is crucial for maintaining the body’s acid-base balance, as an increase in carbon dioxide levels can lead to greater acidity in the bloodstream.

3. Heat Generation: Aerobic respiration also produces heat as a byproduct, which helps warm-blooded animals maintain their body temperature.

4. Enhanced Metabolic Efficiency: Aerobic respiration enables organisms to generate more energy from glucose than anaerobic processes, supporting

activities that require sustained energy, like endurance exercise.

5. Supports Cellular Repair and Growth: The ATP produced through aerobic respiration is essential for cellular repair, growth, and maintenance, helping processes such as DNA replication and protein repair for healthy cell function.

Questions: Write your answers in your notebook

1. How does aerobic respiration contribute to ATP production, and why is this important for cellular functions?

2. What are the significance and role of carbon dioxide and water as by-products of aerobic respiration in maintaining the body’s acid-base balance?

3. In what ways does aerobic respiration enhance metabolic efficiency compared to anaerobic processes, particularly in supporting endurance activities?

Disorders A disorder is a condition that affects the normal functioning of the body or mind.

It is a condition that affects how your body or mind works. It can cause problems with how you feel, think or act. For example; a person with a disorder might have trouble focusing on school, or at work, feeling sad for a long time or having physical symptoms like pain or being tired always.

Disorder can be caused by the environment, our lifestyle and or genetic makeup.

It is important to remember that having a disorder is not a person’s fault, as many people with disorders can manage them with the right support like health habits, medications and therapy.

Activity 3.7 Exploring the Effect of Smoke on Air Quality What you need: Two clear plastic jars, filter paper or cotton balls, stopwatch or timer, a lighter or matches and candle.

What to do:

1. Place one potted plant in each jar. Note: these will be your ‘’smoke and control’’ setup.

2. Cover the top of one jar with cotton balls or filter paper (to represent a filtered environment).

3. Leave the other jar open.

4. Light the candle in a well-ventilated area (outside is better)

5. Allow it to burn for a minute.

6. Carefully bring the smoke towards the open jar.

7. Cover the jar immediately afterward to trap the smoke inside.

8. Leave the jar with cotton balls or filter paper uncovered for the same time but make sure no smoke enters it.

9. Leave both jars for a week as you water it regularly and give equal care to both.

10. Observe each day and note any changes in the plants in your notebook.

Questions

1. How did the smoke affect the plant in the open jar compared to the one ion the filtered jar?

2. What might be the implications of smoke exposure for animals and humans in real life?

3. How does smoke pollution affect air quality?

Activity 3.8 Balloon Lung Model to Show Effects of Vaping What you need:

• Two plastic bottles with the bottoms cut off (can use a plastic water bottle)

• two balloons (to represent lungs)

• cotton balls or tissue pieces (to represent vaping residue)

• rubber bands (to secure balloons to bottle opening) What to do:

1. Place one balloon inside a plastic bottle and stretch the balloon’s open end over the bottle mouth.

2. Secure it with a rubber band.

3. This balloon will represent a healthy lung with no vaping effects.

4. Place some cotton balls or small pieces of tissue inside the second balloon to represent chemicals and particles left by vaping.

5. Place this balloon inside the second bottle, just like before, and stretch its open end over the bottle mouth.

6. Secure it with a rubber band. This balloon represents a lung affected by vaping.

7. Cut a third of the other balloons and make a knot in the necks of them.

8. Stretch the wide opening of the cut balloons over the wide opening of the bottles at the bottom.

9. Pull the knot in the ballon of the first bottle (the “healthy lung”) back and release it. The balloon should expand (inflate) and contract (deflate) easily, simulating how a healthy lung fills with air and releases it smoothly.

10. Pull the knot in the ballon of the first bottle (the “vaped lung”) back and release it.

11. Notice how it is harder to expand because the cotton balls or tissues are in the way, blocking air movement. The balloon may not expand or contract as fully as the first one, just like how vaping can make the lungs stiff and clog the airways.

Question: Write down your ideas on paper as you discuss.

How does vaping affect the lung structure?

Vaping This is the act of inhaling vapour produced by an electronic device called vape or e-cigarette. These devices heat a liquid often containing substances containing nicotine, flavourings and other chemicals, turning it into a mist (vapour) that users can inhale. Unlike traditional cigarettes, vaping doesn’t burn tobacco, but it can still be harmful to health. It’s important for young people to understand the risks, which includes addiction of the substance nicotine and serious lung disorders.

Effect of Vaping on Lung Structure

1. Swollen or inflammation: chemicals in Vape juice can cause inflammation in the lungs leading to swelling and irritation.

2. Reduced function: Damage to the alveoli can reduce their ability to exchange gases making it harder to breathe.

3. Tar and chemicals: like traditional cigarettes, vaping can introduce harmful substance that accumulate in the lungs leading to reduced lungs capacity and increased risk of infections’

4. Long–term risk: Over time vaping can contribute to chronic respiratory disease or even Chronic Obstructive Pulmonary Disease (COPD).

Effects of Smoking on the Structure of the Lungs When we smoke, harmful chemicals enter our lungs and can cause serious damage.

Some of which are:

1. Damage of tiny hair-like structures called cilia that help sweep away dust and mucus making it harder for your lungs to clear out harmful substances.

2. Irritating the lung tissues leading to inflammation. Swelling that causes discomfort and making it harder for air to flow in and out.

3. Damaging tiny sacs at the end of the airways called alveoli where oxygen and carbon dioxide are exchanged. These air sacs when destroyed, reduce the lungs’ ability to take in oxygen and release carbon dioxide leading to a medical condition known as emphysema.

4. Causing the tubes that carry air to your lungs to become small and blocked, making breathing more difficult.

Activity 3.9 The Effects of Smoking on Lung Function What you need: Two balloons, straws and cotton balls What to do:

1. Stretch one balloon a few times to make it flexible, representing healthy, elastic lungs that expand easily.

2. Attach a straw to the opening of the balloon. This straw will act like a windpipe through which air enters the lungs.

3. Place a few cotton balls inside the second balloon. These represent the tar and chemicals that build up in the lungs from smoking.

4. Stretch this balloon less than the first one. This balloon should be harder to expand, showing how smoking makes lungs less elastic and stiffer.

Question: Write your answer in your notepad.

How does smoking affects elasticity of the lungs?

Effects of Smoking on the Structure of the Lungs Smoking has severe and lasting effects on the structure and function of the lungs.

Here are some of the ways that smoking changes the lung structure:

1. Damage to the cilia

• Cilia are tiny, hair-like structures that line the airways and help clear out mucus, dust, and harmful particles from the lungs.

• Effect of Smoking: Chemicals in cigarette smoke paralyse and damage the cilia, making it harder to clear out harmful particles and mucus. This leads to mucus buildup and frequent infections, causing coughing and shortness of breath.

2. Inflammation and narrowing of the airways

• Smoke irritates the airways, causing inflammation and swelling.

• Effect of Smoking: Over time, this inflammation leads to narrowed airways, which restricts airflow, making breathing more difficult. This narrowing can contribute to chronic bronchitis and other respiratory issues.

3. Damage to alveoli (Air Sacs)

• The alveoli are tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged.

• Effect of Smoking: Smoking damages the alveoli walls, reducing their ability to expand and contract properly. This reduces the surface area for gas exchange, leading to conditions like emphysema, where the lungs lose their elasticity, making it hard to exhale fully.

4. Thickened and scarred lung tissue

• Continuous exposure to smoke causes thickening and scarring of lung tissue, reducing the lungs’ flexibility and ability to take in air.

• Effect of Smoking: Scarred lung tissue loses its normal function and makes the lungs stiff, reducing their ability to take in oxygen. This condition, known as pulmonary fibrosis, can significantly impact breathing capacity.

5. Increased Risk of Lung Cancer

• Smoking introduces carcinogens (cancer-causing substances) into the lungs, leading to mutations in lung cells. — See Figure 3.14.

Figure 3.14: Effects of smoking on the lungs Question: Write your answer in your notebook.

How do the normal lungs differ from the smoker’s lungs?

Disorders of the Respiratory System

Asthma: a condition that affects the airways in your lungs. These airways can become inflamed and reduced in making it difficult to breathe.

Table 3.4: Symptoms, causes, effects and treatment of asthma Symptoms • Coughing: Which often happens at night or during exercising.

• Wheezing: A whistling sound when you breath, especially when breathing out

• Shortness of breath: Feeling like you cannot get enough air.

• Chest tightness: A discomfort in the chest making it very difficult to breathe.

Causes • Genetic factors: certain genetic variations can make individuals more likely to develop asthma.

• Environmental triggers

i. Things like pollen, pet dander, dust mites.

ii. Irritants: Smoke, strong odour or air pollution.

iii. Weather changes: Cold air or high humidity.

Effects • Lung function: Asthma can make the lungs lose effective over time making it harder to get enough air.

• It can lead to death Prevention • Avoid what brings about asthma, for example allergens like dust mites, pollen and pet dander

• Smoke: Do not smoke. Avoid places where others are smoking.

• Second hand smoke can cause asthma.

• Strong smells: Avoid strong perfumes.

• Follow your doctor's advice on how to take your medications and checking up regularly.

• Keep indoor air clean.

• Having proper education on asthma helps you to understand its triggers and recognise early symptoms and manage your condition better.

Treatment • Quick-relief medications (e.g., bronchodilators) to open airways and relieve symptoms during asthma attacks

• Controller medications (e.g., inhaled corticosteroids) to reduce inflammation and prevent symptoms

• Avoid exposure to triggers

• Maintain good respiratory hygiene (e.g., using a spacer with inhalers)

• Seek medical attention for severe or persistent symptoms.

Chronic Obstructive Pulmonary Disease (COPD): This is a long- term disease that causes airflow blockage and breathing related problems.

Table 3.5: Symptoms, causes, effects and treatment of Chronic Obstructive Pulmonary Disease (COPD) Symptoms • Shortness of breath, especially during physical activity.

• A persistent cough, often with mucus

• Wheezing (a whistling sound when breathing).

• Frequent lung infections Causes • Long term exposure to harmful substances.

• Smoking cigarettes or using other tobacco products.

• Air pollution

• Dust and chemicals for workplaces.

Effects • Breathing difficulties: people with COPD often find it hard to breathe, especially during activities like walking or climbing stairs.

• Chronic cough: A constant cough that produces mucus is common. This can be uncomfortable and may disrupt sleep.

• Fatigue: Struggling to breathe can lead to tiredness making it difficult to keep up with regular activities.

• Weight loss: some people with COPD may lose weight because they find it hard to eat or feel less hungry.

Prevention • Avoid smoking or vaping and exposure to second-hand smoke.

• Maintain a healthy lifestyle.

• Regular heath checkups

• Get vaccinated.

Treatment • Manage symptoms with supportive care

• The use of antibiotics to treat the underlying infection Pneumonia: an infection in the lungs that makes it difficult to breathe and can cause various symptoms.

Table 3.6: Symptoms, causes, effects and treatment of Pneumonia Symptoms • Cough: A long-lasting cough that brings up mucus or phlegm. The mucus may be yellow, green, or even bloody.

• Difficulty Breathing: It might be hard to breathe, even while resting.

• Chest Pain: A sharp pain in the chest, especially when breathing deeply or coughing.

• Fever and Chills: High temperature with shivers and chills.

• Fatigue: Feeling very tired and low on energy.

Causes • Bacteria: Common bacteria like Streptococcus pneumoniae can cause it.

• Viruses: Flu and other viruses, including COVID-19, can also lead to pneumonia.

• Fungi: Fungal infections can cause pneumonia, especially in people with weak immune systems.

Effects • Difficulty Breathing: Lungs fill with fluid, making it hard to get oxygen.

• Complications: It may lead to serious issues, like lung infection with pus or respiratory failure.

• Long-Term Effects: Some may recover slowly, with long-lasting breathing problems.

Prevention • Vaccinations: Get vaccines for flu and pneumococcal disease.

• Hygiene: Wash hands well and cover mouth/nose when coughing or sneezing.

• Healthy Habits: Avoid smoking and manage health conditions like asthma.

Treatment • Antibiotics: For bacterial infections.

• Supportive Care: Fluids and oxygen to ease symptoms.

• Antiviral Medications: If caused by a virus like the flu.

1. Imagine you are an athlete preparing for a marathon. As you train, your body relies heavily on aerobic respiration to produce the energy needed for long-distance running.

a. How does the efficient production of ATP during aerobic respiration support your endurance and performance throughout the race?

b. What impact might an increase in carbon dioxide production have on your performance, and how does your body adjust to maintain acid-base balance during prolonged exercise?

c. In what ways does the heat generated from aerobic respiration assist in regulating your body temperature while you are running?

2. What is the main cause of smoking –related death worldwide?

A. Heart disease B. Lung cancer C. Stroke D. All the above

3. Which of the following is a short-term effect of smoking?

A. Lung cancer B. heart disease C. shortness of breath D. wrinkles on face

4. Which organ is most affected by smoking?

A. Heart B. lung C. brain D. liver

5. Second hand smoke is harmless. True or False

6. What is Nicotine, and how does it affect the body?

7. Explain the term, breathing.

8. Describe the mechanisms of inhalation and exhalation.

9. Create a concept map of air movement in the human body.