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Module 1: Regulación de la temperatura corporal en animales

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Sistemas de intercambio de calor contracorriente

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Biology - Countercurrent Heat Exchange Systems

Countercurrent Heat Exchange Systems

Countercurrent heat exchange in penguins

Some animals, such as penguins, whales and aquatic birds, have
countercurrent heat exchange mechanisms in limbs that help to maintain core
temperature. Blood vessels carrying blood to and from the limb are adjacent
to each other. Cooled venous blood returning to the body from the end of
the limb gains heat from the arterial blood as it flows along the limb to
the end. As the arterial blood loses this heat and becomes cooler on
reaching the end, the temperature gradient between it and the external
environment becomes less. Heat loss is therefore reduced.

Although fish are poikilothermic [1], tuna and some large sharks are able
to retain some of the heat energy generated by metabolic activity through
countercurrent mechanisms. This increases the efficiency of their muscles,
as the rate of chemical reactions is increased with increase in
temperature.

A reverse mechanism operates in some animals in hot conditions to reduce
overheating of the brain.

Countercurrent heat exchange in tuna and some sharks

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