Question

Define breathing explain the mechanism of breathing in human being

Answer 1

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.

Answer 2

When we breathe in air,it goes through our noses into the nasal cavity. from the nasal cavity,the air achieves our lungs through the breeze pipe.lungs are available in the chest cavity.this depression is surrounded by ribs.a expansive strong sheet called diaphram frames the floor of the chest cavity.breathing includes the development of the diaphram and the rib cage.during inhalation,ribs climbs and outwards and diaphram moves down.this development expands space in our chest cavity and air races into the lungs.the lungs get loaded up with air.

During exhalation,ribs move down and inwards while diaphram climbs to its previous position.this redues the span of the chest cavity and air is pushed out of the lungs.