Following diagram indicates the mechanism of breathing. Identify all the parts A, B, C and D correctly

Options

A. A – Air expelled from lungs, B – Ribs and sternum raised, C – Diaphragm contracted, D – Volume of thorax decreased
B. A – Air expelled from lungs, B – Ribs and sternum raised, C – Diaphragm relaxed, D – Volume of thorax decreased
C. A – Air expelled from lungs, B – Ribs and sternum return to original position, C – Diaphragm relaxed, D – Volume of thorax decreased
D. A – Air entering into lungs, B – Ribs and sternum raised, C – Diaphragm contracted, D – Volume of thorax raised

Answer

D

Explanation

A - Air entering into lungs from the region of high pressure (atmosphere) to low pressure (lungs)
B – Contraction of external intercostal muscles pulls the ribs and sternum raised.
C - Contraction of phrenic muscles of the diaphragm
D – Thoracic cavity increases. And pressure decreases.