IGCSE Coordinated Science: Gas Exchange System 1. Identify on diagrams and name the larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries. 1. Trachea 2. Pulmonary Vein 3. Pulmonary Artery 4. Bronchiole 5. Alveoli 6. Lung 7. Bronchiole 8. Bronchiole 9. Bronchiole 10. Bronchi 11. Larynx 2. List the features of gas exchange surfaces in animals.
Gas exchange surfaces are, in essence, organs that allow the diffusion of gas in and out of the body. For mammals, that would be the lungs. More specifically, gas exchange takes place in the alveoli. There are several key features of gaseous exchange in humans: ● The walls of the alveoli are made from a single layer of cells – allows for gases to easily diffuse in and out of the capillaries. ● The alveoli have a moist lining – The oxygen dissolves into the moist lining and enters the blood stream. ● Large surface area – The lungs contain a lot of alveoli, allowing for more gas to be exchanged. 3. Explain the role of mucus and cilia in protecting the gas exchange system from pathogens and particles. The bronchi in the lungs are lined with something called cilia cells. They are cells that line the lungs with hair-like protrusions. The cilia cells sweep any unwanted microbes or particles out of our lungs and airways.
Scattered in between cilia cells are goblet cells that produce mucus. The role of the mucus is to trap any unwanted particles, making the job of cilia cells easier. The mucus is also protects the cilia cells by lining it with a layer of mucus. 4. Describe the effects of tobacco smoke and its major toxic components (tar, nicotine, carbon monoxide, smoke particles) on the gas exchange system. Overall, tobacco and smoking can have a very negative effect on the gas exchange system. Tar: The presence of tar in our airways causes more mucus to be produced by the goblet cells. In addition, tar also paralyzes our cilia cells, meaning that they cannot properly function and remove the mucus. The result is that excess mucus builds up in our airways. Smokers cough more often to shift the mucus to the back of their throats. The tar also clogs up the alveoli in our lungs, reducing the surface area for gas exchange to take place, therefore resulting in less oxygen entering your body. Tar is also a carcinogen, a substance that increases the risk of cancer. The deposited tar in our lungs raises the risk of lung cancer amongst other diseases such as chronic bronchitis.
Nicotine: The presence of nicotine in our bloodstream raises our hearts’ beat per minute, in addition to increases blood [pressure by narrowing our blood vessels. Carbon monoxide: The carbon monoxide binds with the haemoglobins in our red blood cells, reducing its ability to carry oxygen around our body. As a result, it puts more strain our body’s respiratory system. Smoke particles: The smoke particles may also coat the walls of the alveoli, preventing gas exchange from taking place. 5. State the differences in composition between inspired and expired air. Exhaled air has high levels of CO2 and water vapor while inhaled air has O2 and very little amount or no water vapor. Inspired air has around 21% of oxygen whilst expired air consists of 17% oxygen.
6. Use lime water as a test for carbon dioxide to investigate the differences in composition between inspired and expired air. We can use lime water to investigate the difference between inspired and expired air. Lime water, in the presence of carbon dioxide becomes cloudy. In ambient air, lime water is clear because the ambient air does not contain a significant amount of carbon dioxide. However, if you breathe into a solution of lime water, it turns cloudy/milky as the lime water absorbs the carbon dioxide. 7. Investigate and describe the effects of physical activity on rate and depth of breathing. Exercise and other intense physical activity will increase our rate of breathing, in addition to shortening the depth of our breath. 8. Explain the effects of physical activity on rate and depth of breathing. When cells become more active, such as our muscles when we exercise, they need more oxygen in order to perform aerobic respiration to break down glucose and release energy. As a result, we breath faster in order to deliver more oxygen to cells around our body.