The response of endotherms e.g. man to cold and hot conditions

The response of endotherms e.g. man to cold conditions

1. The hair is raised and brought into a more-or-less vertical position by contraction of erector pili muscle.  Air gets trapped in the spaces between the hairs and being a poor conductor of heat, it serves as an insulator around the animals.  In humans the body hair is much reduced, it’s placed being taken by clothes.  Still, the erector pili muscles contract just the same, resulting in “goose pimple”.  In birds the feathers serve the same function as the hair of mammals, being raised in cold weather.
2. Vasoconstriction: i.e. the arterioles leading to the superficial capillaries constrict.  As a result, the blood flow to the surface of the skin is reduced, thereby cutting down the heat energy from the blood to the surrounding.
3. The metabolic rate increases, the generation of heat inside the body to compensate for heat loss.
4.  The decrease in sweating reduces heat loss through evaporation.
5. Shivering: at very low-temperature skeletal muscles are stimulated to contract and relax automatically leading to production of heat.

The response of endotherms by Behavioral mechanism

1. Engaging in exercises (making a lot of noise in some organism)
2. Taking hot drinks or bath
3. Wearing heavy clothes
4. Burrowing
5. Hibernation

Response of endotherms to hot conditions.

1. The hairs are lowered:  by relaxation of erector pili muscles, so they lie flat against the surface of the skin, less air is trapped between the hairs, insulation is therefore reduced, and heat energy can be lost more readily by conduction, radiation and convection.
2. The arterioles leading to the superficial capillaries dilate.  As a result, the blood flow to the surface is increased and more heat energy can be lost to the surrounding.
3. Sweating or panting occur, and evaporation of water from the moist skin or tongue cools the blood as it flows through the superficial capillaries.  As a means of cooling the human body, sweating is extremely important.  In dogs and cats sweating is substituted with panting.
4. The metabolic rate decreases, reducing heat energy generated in the body.

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