Question

Long answer questions.
Describe the role of ribs and diaphragm in breathing.

Answer 1

Breathing:

1. The process, by which air is drawn in from the atmosphere into the lungs and forced out from the lungs back into the atmosphere is known as breathing.
2. It involves two steps-inhalation and exhalation.

Inhalation:

1. Inhalation or inspiration involves the taking of atmospheric air into the lungs.
2. During inhalation, external intercostal muscles of the ribs contract and pull them upward and outwards to increase the volume of the thoracic cavity.
3. The muscles of the diaphragm contract and move downwards to further increase the volume of the thoracic cavity.
4. Due to the increase in volume, the atmospheric pressure in the lung decreases and as a result, the atmospheric air is pulled into the lung through the nostrils.

Exhalation:

1. Exhalation involves the expulsion of air from the lungs into the atmosphere.
2. During exhalation, internal intercostal muscles contract and the ribs move downwards and inwards.
3. The muscles of the diaphragm move upward during exhalation to come back to their original position.
4. As the volume of the thoracic cavity is reduced, the lungs become compressed and the contained air in it is thus forced into the atmosphere.