3.2 Human Gas Exchange

Question 1

What is the order of the human gas exchange structures?

Answer 1

Trachea
Bronchi
Bronchioles
Alveoli

Question 2

How do humans achieve a high surface area in the lungs?

Answer 2

Millions of alveoli

Question 3

How are alveoli adapted to increase the rate of gas exchange?

Answer 3

Walls are one cell thick to provide short diffusion pathway

Question 4

What process increases the concentration gradient in the lungs?

Answer 4

Breathing

Question 5

How does breathing increase the concentration gradient in the lungs?

Answer 5

Pulls fresh oxygenated air into the lungs

Question 6

Why is having a good blood flow advantageous for human gas exchange?

Answer 6

Blood at the lungs is always low in oxygen

Question 7

How do humans inhale?

Answer 7

External intercostals contract and internal intercostals relax
Diaphragm contracts and pulls downwards
The space in the thoracic cavity increases

Question 8

What happens to the pressure inside the thoracic cavity during inhalation?

Answer 8

Decreases so air rushes in from the atmosphere

Question 9

What does decreased pressure in the thoracic cavity create?

Answer 9

A pressure gradient between the atmosphere

Question 10

How do humans exhale?

Answer 10

Internal intercostals contract and external intercostals relax
Diaphragm relaxes and moves upwards
The space inside the thoracic cavity increases

Question 11

What is the forced expiratory volume?

Answer 11

The greatest volume of air a person can breathe out in one second

Question 12

What is vital capacity?

Answer 12

The greatest volume of air a person can breathe in/out in a single breath

Question 13

What is residual volume?

Answer 13

The air that never leaves the lungs no matter how an individual exhales

Question 14

What is the piece of equipment that can be breathed into to measure breathing?

Answer 14

Spirometer

Question 15

What is tidal volume?

Answer 15

The normal volume of air pulled in/out of the lungs when breathing

Question 16

How can pulmonary ventilation rate be calculated?

Answer 16

tidal volume x breathing rate

Question 17

How does an asthma attack affect the lungs?

Answer 17

Muscles walls of bronchioles contract
Walls of bronchioles secrete more mucus
Diameter of airways reduced
Flow of air reduced

Question 18

Emphysema causes the forced expiratory volume to be reduced due to alveoli merging in the lungs - how does this cause problems?

Answer 18

Less CO₂ removed
Less oxygen absorbed into the blood
Less respiration to provide ATP for muscle contraction

Question 19

Why would merging alveoli cause forced expiratory volume to go down?

Answer 19

Reduced surface area

Question 20

Why would a thickened alveoli wall cause reduced gas exchange?

Answer 20

Longer diffusion pathway

Question 21

The elasticity of lungs can be reduced by lung disease - why is this a problem?

Answer 21

Lungs will not fully inflate during inhalation
Breathing out is no longer passive - have to force breath out

Question 22

When using a sample to study lung diseases, what must be ensured about the sample size?

Answer 22

It is large enough to be representative

Question 23

When using a sample to study lung diseases, what must be ensured about how long the study is done for?

Answer 23

Needs to be done for long period of time to see long term effects

Question 24

When using a sample to study lung diseases, what must be ensured about human trials?

Answer 24

Double blind to avoid bias

Question 25

When testing a new medication what needs to be done?

Answer 25

Tried on humans as well as lab grown tissue