The role of a hormone is one of¬†a chemical messenger in the human endocrine system (hormonal system).¬†Produced by specific glands and organs in the body, hormones get secreted into the blood and other body fluids.¬†The majority of¬†hormones are transported to the circulatory system to other areas of the body,¬†where they influence specific organs and cells.
Functions of Hormones
ENERGY USE AND STORAGE
ELECTROLYTE AND WATER BALANCE
REPAIR AND MAINTENANCE
What are the types of hormone signalling?
¬†Signalling mechanisms that occur in multicellular organisms are:
Autocrine signalling –¬†In autocrine signalling, hormones do not travel to other cells but cause changes in the same cell that release them.
Paracrine signalling –¬†Hormones have the capability to impact isolated cells alongside that of¬†neighbouring cells. Hormones act on local cells through secretion¬†into the interstitial fluid that surrounds the cells. These hormones will then diffuse to nearby target cells. This type of signalling is described as “paracrine signalling”.
Endocrine signalling –¬†When a hormone binds to a target cell receptor, it creates¬†changes within the cell. This, in turn, influences the function within the cell. ¬†Hormone signalling that occurs in this manner is called “endocrine signalling”. The reason for this is that¬†the hormones affect target cells over an area or distance.
Direct signalling –¬†Direct signalling occurs¬†by transferring signalling molecules across gap junctions between neighbouring cells.
How¬†hormones work in the body is that they function as chemical messengers, delivering instructions to particular parts of the body.
Hormones only have the ability to affect cells that display receptors that are unique to them.
Cells can display receptors for multiple hormones at one time.
If a cell shows more receptors for a particular hormone, the cell will be more sensitive to that type of hormone and the messages it sends.
Up-Regulation is when a cell displays more receptors in response to a hormone
Down-Regulation is when a cell reduces its number of receptors for a particular hormone
A hormone can make changes to a cell directly by altering what genes are activated
A hormone can make changes indirectly to a cell by stimulating specific signalling pathways inside the cell that affect other processes.
Cells are influenced by¬†a hormone, only when they express a receptor for that hormone.
Depending on the location of the protein receptor on the target cell and the chemical structure of the hormone, hormones can mediate changes directly by binding to intracellular hormone receptors and modulating gene transcription, or indirectly by binding to cell surface receptors and stimulating signalling pathways.