Hormone Functions Flashcards
Paracrines
Also known as local hormones
Chemicals secreted that diffuse to adjacent cells
Secreted by all cells in a particular tissue & move through extracellular fluid
What cells can hormones effect?
Specific - only able to influence cells that have correct receptor for hormone
Hormone Saturation
Once all receptor molecule are occupied by hormone molecule, addition of more hormones will not produce any greater effect
Protein & Amine Hormones
Attach to receptor proteins in membrane of target cell
Receptor-hormone causes secondary messenger to diffuse through cell & activate particular enzymes
Receptor proteins - specific, lock & key analogy can be used
Limited number of receptor proteins in membrane of each cell
Water soluble - cannot pass through plasma membranes
Protein/Amine Hormone Example
Insulin binds to receptor protein & leads to increase in glucose absorption by cell
When each insulin receptor in cell membrane is bound to insulin, glucose uptake cannot increase any further even if amount of insulin increases
Steroid Hormones
Enter target cells and combine with receptor protein inside cell
Hormone-receptor complex activates genes controlling formation of particular proteins (inhibits/stimulates particular protein synthesis)
Fate soluble
Steroid Hormone Example
Hormones secreted by gonads & adrenal cortex
Oestrogen, progesterone, testosterone, aldosterone, cortisol
How can hormones change functioning of cells?
Activate certain genes in nucleus so particular enzyme/protein is produced
Change shape/structure of enzyme - turned on/off
Change rate of transcription/translation to change rate of production of an enzyme/protein
Enzyme Amplification
Series of chemical reactions in which the product of one step is an enzyme that produces an even greater number of product molecules at the next step
One hormone molecule can trigger the production of more than a billion enzyme molecules
