Question

write the mechanism of breathing in human

Answer 1

The human respiratory system consists of a pair of lungs and a series of air passages leading to the lungs. The entire mechanism of breathing is ruled by two processes inhalation, taking in of oxygen-rich air and exhalation, giving out of the carbon-dioxide-rich air.

Breathing consists of two phases called inhalation and exhalation.

1) Inhalation:-Inhalation is the process or act of breathing in, taking air and sometimes other substances into your lungs.

2) Exhalation:-Exhalation (or expiration) is the flow of the breath out of an organism. In humans it is the movement of air from the lungs out of the airways, to the external environment during breathing.

Answer 2

the process of taking air into and expelling it from the lungs is called breathing.

The action of breathing in and out is due to changes of pressure within the thorax, in comparison with the outside. This action is also known as external respiration. When we inhale the intercostal muscles (between the ribs) and diaphragm contract to expand the chest cavity. The diaphragm flattens and moves downwards and the intercostal muscles move the rib cage upwards and out.

This increase in size decreases the internal air pressure and so air from the outside (at a now higher pressure that inside the thorax) rushes into the lungs to equalise the pressures.

When we exhale the diaphragm and intercostal muscles relax and return to their resting positions. This reduces the size of the thoracic cavity, thereby increasing the pressure and forcing air out of the lungs.