What are hormones?
Hormones are chemicals that move from the producing gland directly into the blood, to act upon every cell in the body and affect the function of cells. They are produced naturally in the body by many different glands, including the thyroid and parathyroid glands (in the neck), the pancreas (in the abdomen), the pituitary gland (in the brain), the adrenal glands (on top of the kidneys), the ovary and testes (sex hormones). Most of these are listed under their individual type of hormone (e.g. sex hormones).
Hormones are chemicals that travel from the producing gland, directly into the bloodstream, and then around the body. They reach and act upon every cell in the body through the bloodstream.
Thyroid Gland Hormone (Thyroxin)
The thyroid gland in the neck produces the hormone thyroxine, which acts to control the rate at which every cell in the body works. It is the accelerator of the body. If thyroxine is lacking, the patient becomes tired and slow. This is a common condition in middle-aged and elderly women. The thyroid hormone not being produced by the thyroid gland can be given as a tablet (thyroxine) by mouth. If used at the correct dosage, as determined by regular blood tests, there should be minimal side effects.
The pituitary gland produces a range of hormones, most of which control other glands. The pituitary gland is therefore the “conductor” of the glandular and hormonal ‘orchestra’ of the body.
Types of hormones:
There are more than a score of hormones in the body, many of which are composed of several subtypes, but the most common are shown in the following table.
|Adrenocorticotrophic (ACTH)||Pituitary gland||Controls level of steroid production by the adrenal glands.|
|Antidiuretic (vasopressin)||Pituitary gland||Controls blood pressure, contraction of intestine, contraction of uterus and urine production.|
|Calcitonin||Thyroid gland||Balances parathormone to control calcium and phosphate levels.|
|Follicle stimulating (FSH)||Pituitary gland||Controls sperm production in males and egg (ova) production in females.|
|Gastrin||Stomach||Stimulates production of hydrochloric acid in the stomach.|
|Glucagon||Pancreas||Controls release of glucose into the blood from the liver.|
|Glucocorticoid (steroids)||Adrenal glands||Regulate carbohydrate, fat and protein levels in the body, affect muscle tone, aid in blood pressure control, stimulate healing, reduce inflammation and allergy responses, and shrink lymphatic tissue. Includes cortisol, cortisone and corticosterone.|
|Growth hormone||Pituitary gland||Controls childhood growth and bone repair. Excess causes acromegaly.|
|Insulin||Pancreas||Controls glucose levels in cells and blood.|
|Luteinising (LH)||Pituitary gland||Controls ovulation and menstruation in female and testosterone production in males.|
|Oestrogen||Ovaries||Causes female sexual features to develop and controls menstruation.|
|Parathormone||Parathyroid glands||Controls balance of calcium and phosphate in blood and bones.|
|Placental lactogen||Placenta||Controls supply of nutrition to the foetus.|
|Progesterone||Ovary, placenta||Controls lining of uterus (endometrium).|
|Prolactin||Pituitary gland||Controls milk production in the breasts.|
|Releasing hormones||Hypothalamus||Stimulates release of hormones from anterior pituitary gland.|
|Secretin||Duodenum||Stimulates pancreas to release specific digestive fluid.|
|Somatostatin||Hypothalamus||Controls growth hormone, thyroxine, insulin and gastrin production.|
|Testosterone||Testes||Causes male sexual features to develop.|
|Thyroxine||Thyroid gland||Controls the metabolic rate of the body.|
|Thyroid stimulating (TSH)||Pituitary gland||Controls the function of the thyroid gland.|