Ventilation in mammals

Question 1

Describe the process of inspiration in humans?

Answer 1

external intercostals contract pulling rib cage up and out. Diaphragm contracts and flattens increasing the volume of the thoracic cavity which leads to a drop in pressure. This pressure drops below that of the atmospheric pressure and leads to air being drawn in down the pressure gradient.

Question 2

How does expiration occur in humans?

Answer 2

external intercostals relax and rib cage moves down and in and also the diaphragm relaxes and domes which decreases the volume of the thoracic cavity which leads to an increase in pressure above the atmospheric pressure so the air moves out the body down the pressure gradient.

Question 3

What is the vital capacity?

Answer 3

the max volume of air inspired or expired per breath

Question 4

What is the inspiratory and expiratory reserve volume?

Answer 4

max volume of air inhaled/exhaled over a normal breath.

Question 5

What is the residual volume?

Answer 5

the volume of air left in the lungs after a full exhale

Question 6

What’s the name given to the residual volume + the vital capacity

Answer 6

total lung capacity

Question 7

What are the important features of the nasal cavity?

Answer 7

1. a large surface area
2. good blood supply
3. hairy lining secreting mucus to trap dust and bacteria
4. moist surfaces to reduce evaporation