gas exchange in humans

Question 1

features of gas exchange surfaces

Answer 1

• large surface area to allow faster diffusion of gases across the surface
• Thin walls to ensure diffusion distances remain short
• Good ventilation with air so that diffusion gradients can be maintained
• Good blood supply to maintain a high concentration gradient so diffusion occurs faster

Question 2

what is the gas exchange surface in humans

Answer 2

alveolus

Question 3

what is the function of the cartilage

Answer 3

The function of the cartilage is to support the airways and keep them open during breathing
allows free flow of air into the lungs
allows flexibility, can breathe even when bent

Question 4

what are goblet cells

Answer 4

cells that produce mucus in the body to trap incoming pathogens and/or dust

Question 5

what are ciliated cells

Answer 5

cells that have tiny hairs on them that beat to move mucus up the nose and throat

Question 6

explain how the process of inhalation occurs

Answer 6

external intercostal muscles contract
ribcage moves upwards and outwards
diaphragm contracts and flattens to increase volume and decrease pressure to allow for more air to diffuse in
air is drawn in

Question 7

explain how the process of exhalation occurs

Answer 7

internal intercostal muscles contract
ribcage moves downwards and inwards
diaphragm relaxes and returns to dome-shape
volume of thorax decreases
pressure increases
air is forced out

Question 8

what is the percentage of oxygen in inspired air

Answer 8

21%

Question 9

what is percentage of carbon dioxide in inspired air

Answer 9

0.04%

Question 10

what is the percentage of nitrogen in inspired air

Answer 10

78%

Question 11

what is the percentage of oxygen in expired air

Answer 11

16%

Question 12

what is the percentage of carbon dioxide in expired air

Answer 12

4%

Question 13

what is the percentage of nitrogen in expired air

Answer 13

78%

Question 14

what is the reason oxygen percentage decreases between inspired air and expired air

Answer 14

oxygen is used from the blood by respiring cells so the oxygen concentration of the blood returning back to the lungs is lower than the air in the alveoli, therefore oxygen diffuses into the blood in the lungs

Question 15

what is the reason the carbon dioxide percentage increases between inspired and expired air

Answer 15

carbon dioxide is released by respiration, this diffuses into the blood from the respiring cells
blood then transports the carbon dioxide to the lungs where it diffuses into the alveoli as the concentration is higher in the blood than the air in the alveoli

Question 16

what are some other differences between inspired and expired air

Answer 16

expired air contains more water vapour than inspired air

Temperature of expired air is higher than inspired

Question 17

why does expired air contain more water vapour than inspired air

Answer 17

water evaporates from the moist lining of the alveoli into the expired air as a result of the warmth of the body

Question 18

what is the test for carbon dioxide

Answer 18

limewater test

Question 19

what does a positive lime water test look like

Answer 19

limewater will become cloudy/milky when co2 is bubbled through it

Question 20

what is the effect on breathing if co2 concentration increases in the blood

Answer 20

breathing increases

Question 21

explain how this effect is coordinated

Answer 21

co2 is acidic therefore pH, of blood decreases
pH drop is detected by brain
brain sends impulses to intercostal muscles to contract more frequently
which brings blood back to state of homeostasis
this is an automatic reflex

Question 22

what is the tissue that keeps the larynx in place

Answer 22

cartilage