Temperature regulation strategies
- Many animals regulate their body temperature through behavior, such as seeking sun or shade or huddling together for warmth.
- Endotherms can alter metabolic heat production to maintain body temperature using both shivering and non-shivering thermogenesis.
- Vasoconstriction—shrinking—and vasodilation—expansion—of blood vessels to the skin can alter an organism's exchange of heat with the environment.
- A countercurrent heat exchanger is an arrangement of blood vessels in which heat flows from warmer to cooler blood, usually reducing heat loss.
- Some animals use body insulation and evaporative mechanisms, such as sweating and panting, in body temperature regulation.
Mechanisms of thermoregulation
- Endotherms, such as birds and mammals, use metabolic heat to maintain a stable internal temperature, often one different from the environment.
- Ectotherms, like lizards and snakes, do not use metabolic heat to maintain their body temperature but take on the temperature of the environment.
- Changing behavior
- Increasing metabolic heat production
- Controlling the exchange of heat with the environment
Increasing heat production—thermogenesis
Controlling the loss and gain of heat
- Circulatory mechanisms, such as altering blood flow patterns
- Insulation, such as fur, fat, or feathers
- Evaporative mechanisms, such as panting and sweating
Vasoconstriction and vasodilation
Countercurrent heat exchange
- Warm arterial blood from the body's core travels down the leg in an artery.
- Arterial blood passes heat to cold venous blood coming back from the foot.
- Arterial blood is now cooler and will lose less heat to the environment as it travels through the foot.
- Cold venous blood ascending from the foot is warmed before it returns to the body's core.
- In sweating, glands in the skin release water containing various ions—the "electrolytes" we replenish with sports drinks. Only mammals sweat.
- In panting, an animal breathes rapidly and shallowly with its mouth open to increase evaporation from the surfaces of the mouth. Both mammals and birds pant, or at least use similar breathing strategies to cool down.