The conditions inside our body must be carefully controlled to allow it to function effectively. Homeostasis is the maintenance of a constant internal environment in the body. The nervous system and hormones are responsible for controlling this.
The body control systems are all automatic, and involve both nervous and chemical responses. It has many important parts, including:
Body temperature is one of the factors that is controlled during homeostasis. The human body maintains the temperature that enzymes work best, which is around 37°C.
If body temperature increases over this temperature, enzymes will denature and become less effective at catalysing important reactions, such as respiration.
This process is controlled by the thermoregulatory centre, which is contained in the hypothalamus in the brain, and it contains receptors sensitive to the temperature of the blood. The skin also has temperature receptors and sends nervous impulses back to the hypothalamus.
The hypothalamus responds to this information by sending nerve impulses to effectors in the skin to maintain body temperature.
The skin contains three layers: The epidermis, dermis and a layer of fatty tissue.
Structures within these layers are involved in thermoregulation.
When we get too hot:
When we get too cold:
The control of body temperature is an example of a negative feedback mechanism. It regulates the amount of:
|Too cold||Too hot|
|Arterioles||Get narrower||Get wider|
|Blood flow in skin capillaries||Decreases||Increases|
|Heat loss from skin||Decreases||Increases|
These diagrams show the processes that take place when vasoconstriction and vasodilation occur.
When the temperature is too high, different processes happen: Vasodilation, sweat production, which both transfer energy from skin to the environment, resulting in a cooling effect.