Question

Short / long answer type questions.
Describe the mechanism of inspiration and expiration in man.

Answer 1

• Inspiration involves bringing in air from outside the body into the lungs. When we breathe in, the size of our chest increases. This happens because when air enters, the lungs expand and the ribs move outwards. Simultaneously, the diaphragm contracts and becomes flat. Thus, the size of our chest increases.
  
• Expiration involves removal of CO2 from the body. When we breathe out, the size of our chest decreases. This happens because when air moves out of our lungs, the lungs contract, the ribs move back, and the diaphragm curves upwards into the chest decreasing the size of the chest.