Question

Upward and downward movement of diaphragm occur consecutively. Why?

Answer 1

The diaphragm is characteristic of mammals. It is a highly muscular and fibrous partition, elevated towards thorax like a dome. The most important function of a diaphragm of mammals is to aid in respiration. Puncturing of diaphragm results in the stoppage of breathing and is fatal. The term phrenic is associated with diaphragm (eg. phrenic muscles, arteries or veins).

Mechanism of Breathing that leads to an inward and outward movement of the Diaphragm.

In general, a man respires about $12-14$ times in a minute.

The main muscles of respiration in normal quiet breathing are muscles of the diaphragm . Larynx does not contribute to breathing movements.

The muscles of ribs ( intercoastal) and diaphragm ( phrenic) are responsible for intake and output of air from lungs. Inspiration in man is an active process, it is the result of muscles contraction. During Inspiration, in humans, the diaphragm and external coastal musles contract.

This moves the lateral thoraic walls outward and upward. During Inspiration, the diaphragm is flattened and that contributes to an increased volume of thoraic cavity.