Question

Explain the process of inspiration and expiration with diagrams.

Accepted Answer

Under normal conditions, an adult person respires 15-20 per minute. It is a process in which a person takes in oxygen for the tissues to work properly and gives out carbon dioxide taken from the blood as a waste product. The pure oxygen is transported to the organs through blood with the binding of haemoglobin.

Mechanism of inspiration:

When the oxygen is inhaled from the surroundings, it moves through the nasal passage, windpipe and reaches to alveoli.

Alveoli are attached to the lungs surface where the gases diffuse into the lungs.

Oxygen is transferred to the lungs when the thoracic cavity expands as a result of the contraction of the diaphragm.

This makes external intercostal muscle contract making the ribs move forward or outwards, this results in decreased internal pressure in the lungs and increased thoracic cavity space.

This favours the oxygen to enter into the lungs and transfer to the body organs.

Mechanism of expiration:

Carbon dioxide is collected from the body organs and transferred to the lungs so that it can be expelled out from the body.

Lungs diffuse the carbon dioxide inside them and the diaphragm relaxes which result in the relaxation of external intercostal muscles thereby decreasing the thoracic cavity.

The pressure in the lungs is increased.

Due to increased pressure, carbon dioxide is expelled out from the lungs – from alveoli to nasal passage and then to the environment.

This is how one respiration takes place.

Respiratory capacities		Respiratory volumes
i)	Residual volume	a)	2800 mL
ii)	Vital capacity	b)	3000 mL
iii)	Inspiratory reserve volume	c)	1100 mL
iv)	Inspiratory capacity	d)	4000 mL

Explain the process of inspiration and expiration with diagrams.

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