Corpus: Inspiration

Inspiration is the phase of the respiratory cycle in which the breath enters the airways and lungs through active breathing.

Inspiration is achieved by tensing the respiratory muscles, with forced breathing also with the aid of the auxiliary respiratory muscles. The tensing of the respiratory muscles creates a negative pressure (-4 kPa when breathing at rest), which overcomes the respiratory resistance and allows air to flow into the lungs.

Around 2/3 of inspiration is generated by contraction of the diaphragm and 1/3 by the external intercostal muscles. The respiratory muscles are innervated by the cervical plexus (segments C3-C5, diaphragm) and the intercostal nerves (segments Th1-Th12, intercostal muscles).

During normal inspiration, only part of the possible filling volume of the lungs is utilised. More air can be channelled into the lungs through further exertion. This proportion is known as the inspiratory reserve volume.

See also: Expiration

In psychology, "inspiration" refers to a mental intuition.