Gas Exchange In Humans

Question 1

Describe inhalation (3)

Answer 1

Diaphragm contracts and flattens
External intercostal muscles contract and move upwards
Volume increases and pressure decreases in the lungs
Forcing air in
Active proscess which requires energy

Question 2

Describe exhalation (3)

Answer 2

Diaphragm relaxes and raises upwards
Internal intercostal muscles contract so the rib cage lowers
Volume decreases and pressure increases so air is forced out
Normal expiration is a passive process

Question 3

The alveolar epithelium is one cell thick
How does this affect diffusion

Answer 3

Shorter diffusion distance

Question 4

How does a large number of alveoli affect diffusion

Answer 4

Increases surface area for gas exchange

Question 5

How does narrow capillaries affect diffusion rate

Answer 5

Red blood cells slow down to squeeze through one at a time, increasing time for diffusion

Question 6

How does a large number of capillaries affect rate of diffusion

Answer 6

Maintains a steep concentration gradient