Question

Upward and downward movement of the diaphragm occurs consecutively.

Answer 1

During inspiration, the diaphragmcontracts and pulls downward while the muscles between the ribs contract and pull upward. ... During expiration, the diaphragm relaxes, and the volume of the thoracic cavity decreases, while the pressure within it increases. As a result, the lungs contract and air is forced out.

Answer 2

the breathing movement and possible due to contration and relaxation of diaphragm. the rib mucles also help these movement. when the ribs rise and diaphragm is lowered at same time, the there is a decrease in pressure on lungs this cause movement of air into the lungs at times of inhalation. on the othet hand then rib come back to their normal position and diaphragm is risen then pressure on in a lungs increases. this cause movement of the air out of the body through the nose in the forms of exhalation