Question

hi acan anyone explain me the machanism of breathing class 11 biology​

Answer 1

Answer:

INHALATION:

During inhalation or inspiration:

1. The diaphragm contracts and is pushed downwards from its dome-shape to a flattened shape.
2. The rib cage and sternum move outwards and upwards.
3. Thoracic cavity increases.
4. External inter coastal muscles contract.
5. Internal inter coastal muscles relax.
6. Air Pressure decreases inside thorax and lungs.
7. thus, external air pressure drives air into lungs at low pressure.

EXHALATION:

During exhalation or expiration:

1. Diaphragm relaxes and moves upwards to dome shape.
2. Rib cage and sternum move downwards and inwards.
3. Thoracic cavity decreases.
4. External inter coastal muscles relax.
5. Internal inter coastal muscles contract for forced expiration.
6. Air Pressure increases inside thorax and lungs.
7. Thus, air is forced out of lungs by compression of thorax and elastic recoil of lungs.