Physiology of Respiration

Here we learn about why we breathe and how we breathe.

Breathing is a fundamental process of the body. It allows us to eliminate toxic carbon dioxide from our bodies while supplying our heart and lungs with oxygen that is necessary for cellular respiration and the generation of energy necessary for an organism to function.

Ordinarily, it is an involuntary function that is controlled by the autonomic nervous system. However, respiration itself is an active process since it requires the contraction of thoracic muscles such as the external intercostal muscles and the diaphragm. As multicellular organisms we have conscious control over our skeletal muscles, and thus we are able to exercise control of our own breathing regardless of the body’s involuntary capability to breathe on its own.

The process of inhalation entails the contraction of the external intercostal muscles which increases the front-to-back width of the thoracic cavity and thereby induces a pressure drop in the lungs, allowing air and oxygen to flow in. Exhalation occurs as the external intercostal muscles and the diaphragm relax so that the thoracic cavity returns to its pre nspiratory state. This way, the lungs experience a rise in pressure and in turn, carbon dioxide and air are forced outward.