1. Which structures in human respiratory system is involved in the process of breathing?

2. The following are events which take place during expiration in a mammal.

(i) the diaphragm intercostal muscles relax.

(ii) the diaphragm returns to its original dome-shape

(iii) the rib cage moves inwards.

(iv) the pressure in the thoracic cavity increases.

(a) List the correct sequence of events which take place during expiration.

(b) Explain what would happen to breathing in a mammal if the intercostal muscles were damaged with disease.