Controling temperature Flashcards
What is the hypothalamus?
The part of the brain at the centre of the control mechanism that keeps internal temperature constant. It coordinates the activities of parts of the body that bring about temperature change
Shivering
Muscles in some parts of the body contract and relax very quickly to produce heat.
Effect of shivering
Heat produced warms blood as it flows through the muscles . Blood distributes heat around the body.
What happens to metabolism when temperature falls below 37?
The speed of chemical reactions like respiration increases to produce more heat when it is cold.
What happens to hairs when temperature drops below 37?
Erector muscles contract to pull hairs on end. Upright hairs trap a layer of warm air next to the skin, which insulates it
Vasoconstriction
Arterioles supplying skin surface capillaries with blood constrict, so not much blood flows through them.
When does vasoconstriction happen?
When the body is too cold
Effect of vasoconstriction
Blood flows through shunt vessels and deep-lying capillaries instead. The blood loses less heat to the air as these are deep beneath the skin below the insulating fatty tissue.
What happens to hair when temperature rises?
Erector muscles relax so hairs lie flat on skin and trap less air.
How does sweat cool the body?
It lies on the surface of hot skin. Water in it evaporates, taking heat from the skin with it and cooling the body.
How does the body secrete more sweat?
The arteriole supplying the sweat gland dilates, bringing more blood so the gland can make more sweat
When does vasodilation happen?
When the body is too hot
Vasodilation
Arterioles supplying skin surface capillaries dilate, bringing more blood to the capillaries
Effect of vasodilation
More blood is brought to skin surface capillaries where it can lose heat
