Medical Questions » Hormones Questions » Question No. 516
| Question: | Would you please explain what hormones are? I do not understand how they work. |
| Answer: | Most people think of hormones in terms of the sex hormones (oestrogen and testosterone), but there are actually over 100 hormones that affect the functioning of every cell in the human body.
Hormones are chemicals of various types that are released by glands such as the pituitary gland (in the brain), thyroid and parathyroid glands (in the neck), pancreas (in the centre of the belly), adrenal glands (on each kidney), ovaries, testes and other less-well-known glands. These chemicals enter the bloodstream, and in this travel to every single cell in the body.
They give instructions to the cells on an enormously wide range of matters that affect the way in which all cells work.
The system is orchestrated by a part of the brain called the hypothalamus, which in turn gives instructions to the pituitary gland which is attached to it. The pituitary releases hormones which travel to other glands through the blood, telling them what to do.
As an example, one of the hormones that the pituitary gland releases is thyroid-stimulating hormone (TSH). This stimulates the thyroid gland to produce more of the hormone thyroxine. Thyroxine controls the rate at which every cell in the body works. If there is more thyroxine, the cell works faster, if there is less thyroxine, it works slower. As the level of thyroxine rises in the blood, the pituitary gland senses this and reduces the amount of TSH produced.
This feedback mechanism regulates not only the thyroid gland and its production of thyroxine, but every other gland in the body, including the production of the sex hormones from the ovaries and testes.
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