Name: Human Respiratory System
Uploaded: 2019-07-19
Duration: 4 min 39 s
Description: Fishes need gills for respiration, while frogs have skin as one of their respiratory organs. Check out this video for details about the respiratory organs in humans.

Question

Explain the process of inspiration and expiration under normal conditions?

Accepted Answer

Inspiration is the step of ventilation in which air enters the lungs. The primary inspiratory muscles are the diaphragm and external intercostal muscles.

Inspiration is initiated by contraction of the inspiratory muscles:

Diaphragm–flattens that extends the superior/inferior dimension of the thoracic cavity.
External intercostal muscles–elevates the ribs and sternum that helps in extending the anterior/posterior dimension of the thoracic cavity.
The activity of the inspiratory muscles causes an increase in the volume of the thoracic cavity.

Release of fouled air to the exterior is called expiration. It is a passive process. It is initiated by the following two muscle movements:

Relaxation of the diaphragm and the external inter-costal muscles returns the diaphragm and sternum to their normal positions, thereby reducing the thoracic volume and lung volume. This in turn leads to an increase in the intra-pulmonary pressure causing the expulsion of air from the lungs.

Explain the process of inspiration and expiration under normal conditions?

Important Questions on Breathing and Exchange of Gases

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