Gas Exchange (Humans)

Question 1

what is the thorax?

Answer 1

top part of your body.

Question 2

what separates the thorax and lower part of body?

Answer 2

diaphragm (muscle)

Question 3

what are the lungs and what are they surrounded by?

Answer 3

like big pink sponges. surrounded by pleural membranes.

Question 4

what protects the lungs?

Answer 4

ribs

Question 5

what runs between the ribs?

Answer 5

intercostal muscles.

Question 6

where does the air you breathe in go?

Answer 6

1. through the trachea.
2. this splits into 2 tubes called bronchi, one going to each lung.
3. the bronchi split into progressively smaller tubes called bronchioles.
4. the bronchioles end at small bags called alveoli where gas exchange takes place.

Question 7

what happens when you breath IN?

Answer 7

1. intercostal muscles and diaphragm CONTRACT.
2. thorax VOLUME INCREASES
3. ribcage pulled up and out
4. PRESSURE DECREASES, drawing air in.
5. diaphragm flattens

Question 8

what happens when you breath OUT?

Answer 8

1. intercostal muscles and diaphragm RELAX.
2. VOLUME DECREASES
3. PRESSURE INCREASES, forcing air out.
4. ribcage pulled down and in
5. diaphragm moves up

Question 9

how are ALVEOLI adapted for gas exchange?

Answer 9

1. huge numbers of them = ENORMOUS SA
2. moist lining = gases to dissolve in
3. very thin walls (one cell thick) = SHORT DIFFUSION DISTANCE
4. great blood supply = maintain HIGH CONC GRADIENT
5. permeable walls = gases diffuse across easily.

Question 10

what are the consequences of smoking to the lungs and circulatory system?

Answer 10

1. damages walls of alveoli, reducing the SA for gas exchange
2. tar damages the cilia in your lungs and trachea. these hairs catch dust and bacteria before they reach the lungs. also keep trachea clear by sweeping mucus back towards mouth. damaged cilia = chest infections more likely.
3. tar also irritates bronchi and bronchioles, encouraging mucus to be produced which can’t be cleared by damaged cilia = smoker’s cough and chronic bronchitis.
4. Carbon monoxide reduces amount of O2 the blood can carry. to make up for this heart rate increases = high blood pressure = damage artery walls = more likely blood clots form = CORONARY HEART DISEASE
5. tobacco smoke = carcinogens = cancer

Question 11

how do you measure the effect of exercise on breathing rate?

Answer 11

1. sit still for 5 minutes.
2. then, for one minute count the number of breaths you take
3. now do four minutes of exercise and as soon as you stop count your breaths for a minute.
4. repeat the steps above, and work out the mean results for resting and after exercise.
5. also get 2 other people to do the same so you get three sets of results to compare

Question 12

how can you investigate the release of carbon dioxide in your breath?

Answer 12

• you can do an experiment with limewater (turns cloudy in presence of CO2) to show that carbon dioxide is released in the presence of carbon dioxide.
  1. set up two boiling tubes with the same amount of limewater in each.
  2. put your mouth around the mouthpiece and breathe in and out several times.
  3. as you breath in, air from the room is drawn in through boiling tube A. this air contains very little CO2 so the limewater remains colourless.
  4. when you breathe out, the air you exhale bubbles through the limewater in boiling tube B. this air contains CO2 produced during respiration, so the limewater turns cloudy.
• since the limewater in boiling tube A remains clear, you can tell that the carbon dioxide in the exhaled air was from respiration, it wasn’t inhaled through boiling tube A. if you’d inhaled the carbon dioxide, the limewater in boiling tube A would have turned cloudy too.