Define breathing explain the mechanism of breathing in human beings 0
Answers
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.
Breathing is a complex mechanical process. it is a involuntary action but it's rate is controlled by respiratory center of brain .
* The space of the thoracis cavity increased or decreased by outward or inward movement of the ribs.
* The floor of thoracis cavity is completely closed by a thin muscular septem called diaphragm.
* Inhalation and exhalation of the air take place continously in respiratory system.