Breathing and gas exchange Flashcards
Where are the lungs?
- In the thorax
- Lungs are elastictend to empty like a ballon
How are lungs protected?
The lungs are enclosed by the ribcage and the diaphragm
What are the lungs surrounded by?
The pleural membranes
What happens to the air you breath?
- When we breath air goes in our nose or mouth and passes down the trachea
- The trachea then splits into two bronchi, one bronchus going into each lung
- Each bronchus then splits into progressively smaller tubes called bronchioles
- Eventually ending with microscopic air sacs called alveoli
How are the walls of the trachea and bronchi supported?
They are supported and kept open when we breath in with rings of cartilage
Describe what happens when you breathe in
- External costal muscle, intercostal muscles (pull ribs up and out) and diaphragm contract (flattens)
- Thorax volume increases
- This decreases the pressure compared with outside air
- This draws air in
Describe what happens when you breathe out
- Internal costal muscles, intercostal muscles (pulls ribs down and in) and diaphragm relax (dome shape)
- Thorax volume decreases
- Higher pressure than air outside thorax (raised slightly above atmospheric pressure)
- Differences in pressure forces air out of lungs
How can you investigate the effect of exercise on breathing rate in humans?
- Sit still for five minutes. Then for one minute count the number of breaths you take
- Then do four minutes of exercise and as soon as you stop count your breaths for a minute
- Two other people also do experiment so three sets of results to compare
- Results should show that exercise increases breathing rate
- Control all variables that might affect your results e.g. time spent exercising using a stopwatch and the temperature of the room using air conditioning or a thermostat
Why does your breathing rate increase when you exercise?
When we exercise our muscles are working harder, and so more energy is required, and so more respiration is required, which means more oxygen is required and so your breaths are faster and deeper
What do alveoli do?
-Carry out gas exchange in the body (gas exchange by diffusion between air in the lungs and blood in capillaries
Describe the gas exchange in the alveoli
- Blood from respiring tissues have given up some of its oxygen and gained carbon dioxide, therefore there is a high concentration of carbon dioxide and a low concentration of oxygen in the blood
- This means that there is a higher concentration of carbon dioxide in the blood than in the alveolus and carbon dioxide diffuses from the blood to the lungs
- There is a higher concentration of oxygen in the alveolus that the blood, so the oxygen diffuses (from air) across the wall of the alveolus and into the blood
- Blood that has gained oxygen and lost carbon dioxide leaves the capillaries and flows back to the heart. The heart then pumps the blood around the body again to supply the respiring cells
How is the alveolus specialised for gas exchange?
- Huge number of microscopic alveoli gives the lungs and enormous SA
- There is a moist lining for the gases to dissolve in
- Alveoli have very thin walls, one cell thick so the gas doesn’t have to diffuse far
- Great blood supply to maintain high concentration gradient
- The walls are permeable, so the gases can diffuse across easily
- ALL MAKE DIFFUSION MORE EFFICIENT
How does smoking damage the alveoli?
Smoking damages the walls inside the alveoli, reducing the surface area for gas exchange and leading to diseases like emphysema
How does the tar from smoking affect the circulatory system and lungs?
- Tar in cigarettes damages the cilia in your lungs and trachea
- These hairs, along with mucus catch a lot of dust and bacteria before they reach the lungs
- The cilia also help to keep the trachea clear by sweeping mucus towards the mouth
- When these cilia are damaged chest infections are more likely - Tar also irritates the bronchi and bronchioles, encouraging mucus to be produced which can’t be cleared very well by damaged cilia, this causes smokers cough and chronic bronchitis
How does the carbon monoxide in cigarette smoke affect the circulatory system and lungs?
- The carbon monoxide in smoke binds to the haemoglobin in your RBC rather than oxygen and so reduces the amount of oxygen the blood can carry
- To make up for this, heart rate increase, which leads to increase in blood pressure
- High blood pressure damages the artery walls, making the formation of blood clots more likely
- This increases the risk of coronary heart disease (e.g. heart attacks)
What is the relationship between smoking and cancer?
Smokers are more likely to have cancer because tobacco smoke contains a lot of carcinogens
