Homeostasis and Body Temperature

Homeostasis is the regulation of the internal conditions of a cell or organism in response to internal and external changes

It is important because it keeps conditions constant for enzyme action and cell function

Homeostasis includes the control of:

-blood glucose concentration

-body temperature

-water and ion levels

The control systems may involve:

-responses using nerves

-chemical responses using hormones

All control systems include:

-receptors (which detect stimuli)

-coordination centres e.g brain, spinal chord and pancreas (which receive and process information from receptors)

-effectors e.g muscles or glands (which bring about responses that restore optimum levels)

Negative feedback cycle:

-a receptor detects a change in stimulus

-the coordinating centre compares the stimulus to a set point

-an effector then produces a response to correct any difference from the set point

-this cycle then begins again

Human body temperature should be kept at around 37C as this gives an optimum temperature for enzymes to work

The thermoregulatory centre in the brain

-monitors and controls body temperature

-has receptors that monitor the temperature of the blood flowing through the brain

-receives information (impulses) from temperature receptors in the skin

If the body temperature is too high:

-blood vessels widen, directing more blood to the surface of the skin (vasodilation)

-more sweat is produced from the sweat glands and evaporates

-both of these mechanisms cause a transfer of energy from the skin to the environment

If the body temperature is too low:

-blood vessels narrow, directing blood away from the surface of the skin (vasoconstriction)

-sweating stops

-skeletal muscles uncontrollably contract and relax quickly (shiver), which transfers more heat to the blood