explain the events in expiration and inspiration. 5 mark question
Answers
Answer:
The first phase is called inspiration, or inhaling. When the lungs inhale, the diaphragm contracts and pulls downward. ... When the lungs exhale, the diaphragm relaxes, and the volume of the thoracic cavity decreases, while the pressure within it increases. As a result, the lungs contract and air is forced out.
OR
The processes of inspiration (breathing in) and expiration (breathing out) are vital for providing oxygen to tissues and removing carbon dioxide from the body. Inspiration occurs via active contraction of muscles – such as the diaphragm – whereas expiration tends to be passive, unless it is forced.
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Answer:
The processes of inspiration (breathing in) and expiration (breathing out) are vital for providing oxygen to tissues and removing carbon dioxide from the body. Inspiration occurs via active contraction of muscles – such as the diaphragm – whereas expiration tends to be passive, unless it is forced.
INSPIRATION
Inspiration is the phase of ventilation in which air enters the lungs. It is initiated by contraction of the inspiratory muscles:
Diaphragm – flattens, extending the superior/inferior dimension of the thoracic cavity.
External intercostal muscles – elevates the ribs and sternum, extending the anterior/posterior dimension of the thoracic cavity.
The action of the inspiratory muscles results in an increase in the volume of the thoracic cavity. As the lungs are held against the inner thoracic wall by the pleural seal, they also undergo an increase in volume.
EXPIRATION
Expiration is the phase of ventilation in which air is expelled from the lungs. It is initiated by relaxation of the inspiratory muscles:
Diaphragm – relaxes to return to its resting position, reducing the superior/inferior dimension of the thoracic cavity.
External intercostal muscles – relax to depress the ribs and sternum, reducing the anterior/posterior dimension of the thoracic cavity.
The relaxation of the inspiratory muscles results in a decrease in the volume of the thoracic cavity. The elastic recoil of the previously expanded lung tissue allows them to return to their original size.