What is hormonal control?

The endocrine system affects bodily activities by releasing chemical messengers called hormones into the blood stream. The endocrine system as a whole sends messages to cells in any part of the body. The endocrine system brings about changes in the metabolic activities of all body tissue. Hence, affects growth. Action is slow. Hormones can take hours or even days to produce their response. The effects produced by hormones are more lasting and may even be permanent.  

Hormones (Greek: “set in motion”) are secretion of the endocrine glands and one of the most important substance that control the body chemistry- “chemical messengers”.Endocrine glands differ from exocrine glands in the fact that endocrine glands are ductless glands and pour their secretions directly into the blood stream. Once a hormone is released into the blood, it is carried to target cells that respond to the hormone. All body cells are target cells for one or more hormones, but all cells do not respond to a particular hormone. Hormones are changed functionally and structurally as they are metabolised.

They are partially used by the cells and partially excreted in the urine. The endocrine system is made up of endocrine glands and tissues. The endocrine glands of the body include the pituitary gland, thyroid, parathyroid, adrenal, pancreas, pineal and the thymus.

  • Endocrine tissues: these are several organs of the body that contain endocrine tissue but are not exclusively endocrine glands. Example: pancreas, kidneys, stomach, small intestines, ovaries (female gonad), testes (male gonad), skin, heart and placenta.
  • Endocrine glands: These are ductless glands. They secrete their products(hormones)into the extra cellular space around the cells. The secretions then pass into capillaries to be transported in the blood. Example: pituitary, thyroid, adrenal.
  • Exocrine glands: These have ducts They secrets their products (oil, sweat, enzymes) into ducts. The ducts carry the secretion into body cavities, lumen of various organs or body surface. Example: Sweat gland, sebaceous gland, digestive gland.