11. Gas Exchange in humans

Question 1

What are features of gas exchange surfaces?

Answer 1

• large surface area
• thin
• good blood supply
• good ventilation with air

Question 2

What are differences between inspired and expired air?

Answer 2

expired air has:
- less oxygen
- more CO2
- more water vapour

Question 3

Why does expired air contain more water vapour than inspired air?

Answer 3

moisture evaporates from the cells of the gas exchange surface

Question 4

Why does expired air contain more CO2 than inspired air?

Answer 4

CO2 is a waste product of respiration: must be removed from the body

Question 5

Why does expired air contain less oxygen than inspired air?

Answer 5

oxygen is used by cells during aerobic respiration

Question 6

How can you investigate the composition of inspired and expired air?

Answer 6

using limewater - presence of CO2 turns it milky/cloudy

Question 7

Describe the effects of physical activity on the rate and depth of breathing.

Answer 7

rate and depth of breathing increases with exercise

Question 8

_________ increases with exercise.

Answer 8

rate and depth of breathing

Question 9

Run an experiment to investigate the effects of physical activity on the rate and depth of breathing.

Answer 9

1. measure your breathing rate at rest (breaths p/ min)
2. assess the depth of your breathing
3. run on the spot for two minutes
4. measure breathing rate again and assess depth of breathing again
5. repeat previous step 2 min after ed of exercise, then again after 2 min

Question 10

What is the function of cartilage in the trachea?

Answer 10

support the airway and help to keep it open

Question 11

Where is cartilage found? What is it?

Answer 11

it is a tough material found in the trachea in rings

Question 12

What is the thorax?

Answer 12

the chest

Question 13

What happens when you breathe in?

Answer 13

• volume of thorax increases
• pressure inside decreases
• air pushed into lungs

Question 14

What happens when you breathe out?

Answer 14

• volume of thorax decreases
• pressure inside increases
• air pushed out of lungs

Question 15

What is the diaphragm?

Answer 15

a sheet of muscle below the lungs that helps to ventilate the lungs

Question 16

What happens to the diaphragm in breathing in/out?

Answer 16

Breathing in: diaphragm contracts
Breathing out: diaphragm relaxes

Question 17

What happens to the internal intercostal muscles in breathing in/out?

Answer 17

Breathing in: relax
Breathing out: contract

Question 18

What happens to the external intercostal muscles in breathing in/out?

Answer 18

Breathing in: contract
Breathing out: relax

Question 19

What happens to the ribcage in breathing in/out?

Answer 19

Breathing in: moves upwards and outwards
Breathing out: moves downwards and inwards

Question 20

In breathing, what causes the ribs to move?

Answer 20

the action of internal and external intercostal muscles

Question 21

The action of internal and external intercostal muscles…

Answer 21

causes the ribs to move

Question 22

Why does rate and depth of breathing increase with physical activity?

Answer 22

1. increased carbon dioxide concentration in the blood
2. this is detected by the brain
3. leads to an increased rate and greater depth of breathing to expel the carbon dioxide from the body

Question 23

What is the role of goblet cells?

Answer 23

Produce and secrete sticky mucus, lining inside of trachea. Pathogens and particles in inspired air become trapped in it.

Question 24

Which cells produce mucus?

Answer 24

goblet cells

Question 25

What is the role of ciliated cells?

Answer 25

cilia move and sweep mucus out of the breathing system towards the throat, carrying away trapped pathogens or particles

Question 26

Which cells sweep mucus away?

Answer 26

ciliated cells

Question 27

What is mucus?

Answer 27

a sticky substance secreted by goblet cells that helps to trap particles and pathogens

Question 28

What is harmful for cilia?

Answer 28

smoking

Question 29

Smoking harms _______.

Answer 29

cilia