Write the mechanism of breathing
Answers
Answer:
Air moves in and out of the lungs in response to differences in pressure. When the air pressure within the alveolar spaces falls below atmospheric pressure, air enters the lungs (inspiration), provided the larynx is open; when the air pressure within the alveoli exceeds atmospheric pressure, air is blown from the lungs (expiration). The flow of air is rapid or slow in proportion to the magnitude of the pressure difference. Because atmospheric pressure remains relatively constant, flow is determined by how much above or below atmospheric pressure the pressure within the lungs rises or falls.
Inhalation....
In order for air to be drawn into the lungs during inhalation the volume of the thorax must increase. This is brought about due to the contraction of respiratory muscles. The diaphragm contracts and flattens and the intercostal muscles contract to pull the ribs up and out. The increased volume within the thoracic cavity lowers the pressure within the lungs with respect to the atmospheric pressure. Consequently, air is drawn into the lungs down a pressure gradient.
Exhalation
Inhalation is now complete and the next step is exhalation. The diaphragm relaxes and moves up and the relaxation of the intercostal muscles moves the ribs in and down. This has the effect of decreasing the volume within the thoracic cavity and increasing the pressure within the lungs with respect to atmospheric pressure. As a result, air moves out of the lungs down a pressure gradient.