Question

Which of the following are necessary for the process of breathing in man?

• A. Contraction of diaphragm
• B. Contraction-relaxation of heart
• C. Relaxation of ribs muscle
• D. Both A and C

Answer 1

The correct option is D Both A and C

The process of breathing involves-
(a) Inspiration
(b) Expiration
The process of inspiration is as follows:
1. Contraction of diaphragm
2. Contraction of ribs muscles
3. Enlargement of thoracic cage
4. Inhalation of air
5. Gaseous exchange
The process of expiration is as follows:
1. Relaxation of diaphragm
2. Relaxation of ribs muscle
3. Shortening of thoracic cage
4. Exhalation of air.