Hormone

Hormone (from the Greek hormān = to stimulate, setting in motion) is a product of a gland with inner secretion (endocrine gland). It is a substance which acts as a signal molecule conducting information from one tissue to another. Hormones are transported via the blood.

Secretin was the first hormone identified in the human body (in 1902, by the English physiologists Ernest Starling and William Bayliss).

Hormones are produced in special glands which are distributed in various parts of the body. They are transported via the blood to the target cells. Endocrine glands (glands without ducts) are responsible for production and release of the majority of hormones. They are called this way because they release their products directly into the bloodstream (unlike the exocrine ones).

How hormones work
Nervous and endocrine systems are two systems which are responsible for controlling the human body. Hormones have a much slower effect in comparison to nerves. The most of the hormones which play role in basic body functions, such as growth and reproduction, act very slowly. In general, hormones are associated with controlling or influencing chemical processes in target cells. For example determining the pace in which the cells use nutrients for creating energy or if the cells will be producing milk, hair or other products of the metabolism in the body.

Hormones have various effects. Hormones produced in endocrine cells have a general effect (e. g.: insulin and sex hormones). There are also hormones with a local effect – e. g. secretin. Secretin is produced in duodenum as a response for the presence of food in the duodenum. Secretin is transmitted via the blood to the pancreas and encourages a release of a watery juice with enzymes needed for the digestion.

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