Homeostasis and hormones
Human enzymes usually work best at 37ºC, which is human body temperature. This can be measured in several places, including the ear, finger, mouth and anus.
There are various ways to measure body temperature, including using a clinical thermometer, heat-sensitive strips, digital probes or thermal imaging cameras.
Extremes of body temperature are dangerous:
The body’s temperature is monitored by the brain. If you are too hot or too cold, the brain sends nerve impulses to the skin, which has three ways to either increase or decrease heat loss from the body’s surface:
Muscles can also receive messages from the brain when you are cold. They respond by shivering, which warms you up.
|Too cold||Too hot|
A - Hair muscles pull hais on end.
B - Erect hairs trap air.
C - Blood flow in capillaries decreases.
D - Hair muscles relax. Hairs lie flat so heat can escape.
E - Sweat secreted by sweat glands. Cools skin by evaporation.
F - Blood flow in capillaries increases.
A very common mistake in exams is to write that the blood vessels move up and down in the skin. The blood vessels do not move during vasodilation and vasoconstriction.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.