Mammalian diving reflex
Submerging the face into watercauses the mammalian diving reflex, which is found in all mammals, but especially in marine mammals(as, for example, whalesand seals.) This reflex puts the body into oxygen saving modus to maximize the time that can be spent under water. The effect of this reflex is larger in cold water than in warm water, and includes three factors:
- Bradycardia, a reduction in the heartrate (of up to 50% in humans).
- Peripheral vasoconstriction, the restriction of the blood flow to the extremities to increase the blood and oxygen supply to the vital organs, especially the brain.
- Blood shift, the shifting of blood to the thoracic cavity, i.e. the chest between the diaphragmand the neck to avoid the collapse of the lungsunder higher pressure during deeper dives.
Thus, both a conscious and an unconscious person can survive longer without oxygenunder water than in a comparable situation on dry land.
This reaction is similar to the body's reaction to cold water dousing.it:Riflesso di immersione
Categories: Diving medicine| Reflexes
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It uses material from the http://en.wikipedia.org/wiki/Mammalian+diving+reflex Wikipedia article Mammalian diving reflex.