1.5 Expiration and Inspiration in Humans

Question 1

what is the effective mechanism for breathing?

Answer 1

• ensure continual supply of fresh air in lungs

- large diffusion gradient for gases to exchange

Question 2

what is it when air is being pulled into the lungs?

Answer 2

negative pressure breathing

Question 3

what kind of pressure breathing mechanism is employed by humans?

Answer 3

negative pressure breathing

Question 4

breathing mechanism employed by amphibians where air is pushed into lungs

Answer 4

positive pressure breathing

Question 5

what does Boyle’s law state about the relationship of pressure and volume?

Answer 5

the pressure of gas increases as volume decreases

Question 6

how does inspiration work?

Answer 6

1. external intercostal muscles contract
   - rib cage expands and moves up
   - diaphragm contracts and moves downward
2. volume of thoratic cavity increases
   - lungs expand
   - pressure decreases
3. air from environment moves into lower pressure area- lungs

Question 7

how does expiration work?

Answer 7

1. external intercostal muscles relax
   - rib cage relaxes
   - diaphragm relaxes and moves up
2. volume of thoratic cavity decreases
3. air from lungs moves into the environment