help on homeostasisWatch
This is the definition from a medical site:
Homeostasis: A property of cells, tissues, and organisms that allows the maintenance and regulation of the stability and constancy needed to function properly. Homeostasis is a healthy state that is maintained by the constant adjustment of biochemical and physiological pathways.
Let's start off with what homeostasis is. It is to put simply, the balance of equilibrium maintained in your body so the enzymes can work properly without getting denatured and your body can keep on carrying out the process normally.
The main part of homeostasis which I think you learn is the control of temperature. To maintain body temperature, you have temperature sensory receptors on your skin and in your hypothalamus. The receptors on your skin detect temperature changes in your external environment while those in your hypothalamus detects changes of blood temperature inside your body. If your blood temperature increases, your body needs to cool down and it does the following.
1) Vasodilation occurs - arterioles near the skin surface dilate making blood to flow closer to the skin. As a result of increased radiation, your blood loses temperature and your body cools. If the skin is pressed against a cool surface, the cooling results from conduction
2) Increased sweating - as temperature rises, sweating increases. As sweat evaporates from the surface of the skin, heat is lost, cooling the blood below the surface.
3) Effect of hair or feathers - as temperature increases, the (erector pili - don't think you need to know this for GCSE) hair muscles in the skin relax which makes the hair on the skin lie flat close to the skin. This avoids trapping an insulating layer of air.
When your body temperature drops, you need to warm up. For this, your body does the following,
1) Vasoconstriction - arterioles near the surface of the skin constrict. Very little blood flows through the capillary network close to the skin. The blood is kept well below the surface and very little heat is lost through radiation
2) Decreased sweating - as temperature falls, rate of sweating falls and sweat production will stop entirely. This greatly reduces cooling by the evaporation of water from the surface of the skin although some evaporation from the lung still continues.
3) Raising the body hair or feathers - as temperature falls, the erector pili muslces in the skin contract, pulling hair or feathers erect. This traps insulating layer of air and reduces cooling through the skin
4) Shivering - as body temperature falls, the rapid, involuntary contracting and relaxing of the large voluntary muscles causes the body to shiver. The metabolic heat from the exothermic reactions warm up the body instead of moving it.
This is the major part of homeostasis which I assumed you are talking about. If you want to know more about blood sugar levels or pH control of the blood etc, please let me know. I will answer that as well. Also, if you want me to explain anything further from what I mentioned, just ask.