哺乳類動物潛水反射

[咖哩]

自由潛水者需要利用這個基本的生物效應，增進在水下滯留的時間，主要的效應如下：
1 心跳減緩(減緩程度甚至可以達到百分之五十)。
2 血液的重新分配，將富氧的血液保留給需要氧氣的器官，例如大腦。
3 肺腔充血，由於潛到深處後肺臟會受到壓力的擠壓而變小，而胸腔內多餘的空間若無液體填補，將會造成坍塌(肋骨斷裂)，血液會在潛水時滲入胸腔多餘的
空間支撐胸腔(所以自由潛水選手可以下到兩百公尺，而保有完整的胸腔)。
我個人還要再補充一點他所沒有提到的：
胰臟會釋放出更多的紅血球進入血液裡，以利人體的氧攝取率。

以下是原文：

Mammalian diving reflex
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Human babies have reflexes to swim without training and holding their
breath underwater.

Submerging the face into water causes the mammalian diving reflex,
which is found in all mammals, but especially in marine mammals (as,
for example, whales and seals.) This reflex puts the body into energy
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 heart rate (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 diaphragm and the neck to avoid the collapse of the
lungs under higher pressure during deeper dives.

Thus, both a conscious and an unconscious person can survive longer
without oxygen under water than in a comparable situation on dry land.

This reaction is similar to the body's reaction to cold water dousing.

以上 資料來源 ： 維基線上百科全書