diving reflex

div·ing re·flex

a reflex by which immersing the face or body in water, especially cold water, tends to cause bradycardia and peripheral vasoconstriction; mean aortic pressure is little affected because the reduction in cardiac output tends to balance the increased peripheral resistance that reduces peripheral blood flow. Although relatively minor in most humans, the changes can be profound in some species of diving animal, for example, ducks and seals.

diving reflex

n.

A reflexive response to diving in many aquatic mammals and birds, characterized by physiological changes that decrease oxygen consumption, such as slowed heart rate and decreased blood flow to the abdominal organs and muscles, until breathing resumes. Though less pronounced, the reflex also occurs in certain nonaquatic animals, including humans, upon submersion in water.

The physiologic responses—apnoea, bradycardia, peripheral vasconstriction, increased arterial blood pressure—to hypoxia, which were first described in diving simulations of aquatic animals

div·ing re·flex

(dīv'ing rē'fleks)

A reflex by which immersing the face or body in water, especially cold water, tends to cause bradycardia and peripheral vasoconstriction; relatively minor in most humans.