Question
Describe the mechanism of breathing in a mammal under the following subheadings.
(a) Inhalation
(b) Exhalation
(a) Inhalation
(b) Exhalation
Answer
(a) Breathing in or inhalation or inspiration
- External intercostals muscles contract while internal intercostal muscles relax.
- This causes lifting/raising of the ribcage upwards and outwards.
- Muscles of diaphragm contract hence flattens.
- The volume of the thoracic cavity increase and pressure decreases than the atmospheric pressure.
- The higher air pressure in the atmospheric pressure forces air into the lungs.
- The lungs inflates
(b) Breathing out or exhalation or expiration
- External intercostal muscles relax, while internal intercostal muscles contract.
- This causes the ribcage to move downwards and inwards.
- The muscles of the diaphragm relax and the diaphragm assumes a dome shape.
- This makes the volume of the thoracic cavity to decrease while pressure increases than the atmospheric pressure.
- Higher pressure in the thoracic cavity forces air out of lungs.
- The lungs deflate.
- External intercostals muscles contract while internal intercostal muscles relax.
- This causes lifting/raising of the ribcage upwards and outwards.
- Muscles of diaphragm contract hence flattens.
- The volume of the thoracic cavity increase and pressure decreases than the atmospheric pressure.
- The higher air pressure in the atmospheric pressure forces air into the lungs.
- The lungs inflates
(b) Breathing out or exhalation or expiration
- External intercostal muscles relax, while internal intercostal muscles contract.
- This causes the ribcage to move downwards and inwards.
- The muscles of the diaphragm relax and the diaphragm assumes a dome shape.
- This makes the volume of the thoracic cavity to decrease while pressure increases than the atmospheric pressure.
- Higher pressure in the thoracic cavity forces air out of lungs.
- The lungs deflate.
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