PSL301H1 Lecture Notes - Lecture 2: Surface Tension

• School: UTSG
• Department: Physiology
• Course: PSL301H1
• Professor: Christine Wong

Document Summary

Respiratory muscles v inspiratory muscles: diaphragm muscle, upper airway muscles, sternocleidomastoids, scalenes, external intercostals v expiratory muscles, abdominal muscles, internal intercostals v there are two types of respiratory muscles, inspiratory muscles. Activated during expiration v inspiratory muscles: the main inspiratory muscle is the diaphragm, other inspiratory muscles include. Internal intercostals: expiratory muscles are not normally contracted during regular breathing because expiration is a passive action. Natural expiration occurs with the relaxation of the elastic fibers and surface tension of the lungs. These muscles usually have no activity: however, in some circumstances, there is a need to accelerate the elimination of carbon dioxide or a need to provide more oxygen to the lungs as in excessive sighing. In these situations, the internal intercostals are activated to facilitate the contraction of the lungs and the abdominal muscles will contract to push the diaphragm and other organs against the rib cage. This reduces the size of the thorax.