importance of cell signalling
cells need communicate to control processes inside the body and respond to changes in the environment
cell signalling starts…
when one cell releases a messenger molecule such as a hormone. this travels to another cell, where it is detected because it binds to a receptor on the cell membrane. this triggers a change in the cell, e.g. chemical signals sent off.
membrane bound proteins…
act as receptors for messenger molecules
receptor proteins
have specific shapes so that only messenger molecules with a complementary shape can bind to them. different cells have different types of receptor, meaning they respond to different messenger molecules. when a cell responds to a particular molecule it is called the TARGET CELL. cells can have many combinations of receptor cells they are not restricted to 1.
examples of hormone messenger molecules
- Glucagon is a hormone released when there isn’t enoughglucose in the blood. It binds to receptors on liver cells causing liver cells to break down stores of glycogen to glucose.
- FSH hormone is released by the pituitary gland during the menstrual cycle. It binds wuth receptors on cells in the ovaries, causing an egg to mature, ready for ovulation.
- FSH can also bind to cells in the testes to initiate the production of sperm.
role of drugs
some drugs also bind to receptors in cell membranes. they either trigger a response or block a receptor preventing it from working.
drug examples
- Morphine binds to the same recepters an endorphins and triggers a reduction in pain signals that are sent.
- Antihistamines block histamine receptors on the surface of cells preventing histamine from binding, therefore reducing inflammation.
define antagonistic molecules
a molecule that blocks the action of another.