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Insulin is a hormone, that means it is a chemical secreted into the blood by an endocrine organ and carried around the body to a target organ. Insulin helps to control the amount of glucose dissolved in the blood. Insulin prevents the blood sugar level from rising too high. It is also necessary to have insulin in your blood for respiration to take place. Without insulin cells can only get energy from fat and this causes serious problems. The control of blood sugar level is a homeostatic mechanism.
Definitions:
Hormone: this is a chemical secreted directly into the blood by an endocrine organ, it carries a message to a target organ. A hormone is a chemical messenger.
Endocrine Organ: this is an organ which secretes a chemical messenger or hormone directly into the blood. (c.f. an exocrine organ.) Endocrine organs make hormones.
Target Organ: this is any organ which is affected by a hormone. Almost every organ in the body is affected by one or more hormones. Target organs ar controlled by hormones.
Hypothalamus: this is a region at the base of the brain which monitors the conditions of your blood. It measures how much water, salts, bicarbonate ions and sugar is present; it also measures blood temperature. The hypothalamus helps to control the pituitary gland.
Pituitary Gland: this is the Master Endocrine Gland. It secretes hormones which control other endocrine glands.
Homeostasis: this is the mechanism for keeping your internal conditions constant. Blood sugar control is one example of homeostasis/a homeostatic mechanism. The other important ones are: osmoregulation, & thermoregulation.
Negative feedback: this is exactly the opposite of positive feedback! Another page in this Web Site to explain it. It is a switching off mechanism.
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