Page 11 - 84 human physiolofy part-1

Homeostasis

Case Study

Heat stroke and Heat exhaustion

If you have ever tried to do some sort of heavy manual labor on a hot day or competed in a
physical competition you may have experienced dizziness and weakness. In some cases when it is
severe enough you may have even gone as far as to collapsing and loss of consciousness. This is known
as heat exhaustion. Heat exhaust happens when your body is trying to get rid of excessive heat and
keep its temperature at a optimal place. When the body is trying to get rid of a lot of heat you will start
to sweat in large amounts which will lead to a significant reduction of blood volume. The body also
diverts the blood to the skin from other areas of the body. With both of these changes the body
produces a reduction in blood pressure which will reduce the blood flow to the brain and give you the
symptoms described above. heat stroke is a far more serious condition. This happens when the body's
temperature rises out of control due to the failure of the thermoregulating system. If the body is unable
to reduce its temperature due to outside or physical influences the brain will start to malfunction.
Delirium and loss of consciences set in. The center of the brain controlling the sweat glands will stop
functioning halting the production of sweat. This causes the body's temperature to rise even faster.
furthermore with the increase of the body's temperature the metabolic process will speed up causing
even more heat in the body. If left untreated this will result in death. One of the easiest ways to spot
heat stroke is the skin. If it is flushed due to the increase of blood flow but dry because the sweat glands
have stopped secreting the individual will need medical attention fast.

Other Examples

• Thermoregulation
• The skeletal muscles can shiver to produce heat if the body temperature is too low.
• Non-shivering thermogenesis involves the decomposition of fat to produce heat.
• Sweating cools the body with the use of evaporation.
• Chemical regulation
• The pancreas produces insulin and glucagon to control blood-sugar concentration.
• The lungs take in oxygen and give off carbon dioxide, which regulates pH in the blood.
• The kidneys remove urea, and adjust the concentrations of water and a wide variety of ions.

Main examples of homeostasis in mammals are as follows:

• The regulation of the amounts of water and minerals in the body. This is known as
osmoregulation. This happens primarily in the kidneys.
• The removal of metabolic waste. This is known as excretion. This is done by the excretory
organs such as the kidneys and lungs.
• The regulation of body temperature. This is mainly done by the skin.
• The regulation of blood glucose level. This is mainly done by the liver and the insulin and
glucagon secreted by the pancreas in the body.

Most of these organs are controlled by hormones secreted from the pituitary gland, which in turn is
directed by the hypothalamus.

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