endocrine system Flashcards
What is the main function of the endocrine system ?
is to maintain homeostasis.
is the production and regulation of chemical substances called hormones.
hormones?
are signaling molecules that co-ordinate activities in different parts of the body.
How are hormones released?
Hormones are released by specific glands and are transported all around the body
Pheromones
some hormones act outside of the body. chemicals are released out into the external environment.
Example of pheromones
bees are all under the influence of the hormones being released by the queen bee. the ovaries in the other female bees will not develop due to this hormone.
what are the classes of hormones ?
polypeptides, amines and steroids
Polypeptides
water soluble
eg. insulin controls blood sugar levels
amines
water soluble
eg. thyroxine handling of iron in the body
What is another name for epinephrine?
adrenaline
How do water soluble hormones reach their target cells?
They cannot diffuse through the plasma membranes of target cells. They bind to cell-surface receptors. they induce changed in cytoplasmic molecules and sometimes alter gene transcription
How do lipid soluble hormones reach their target cells?
They diffuse out across the membranes of endocrine cells, they bind to transport proteins in the blood then diffuse into the target cells and bind to receptors in the cytoplasm or nucleus. Trigger changes in gene transcription.
Endocrine gland
ductless glands that secrete hormones directly into the surrounding fluid.
Exocrine glands
have ducts
what is the primary link between the nervous and endocrine system ?
Hypothalmus
describe negative feedback?
Response to internal or environmental stimulus by secreting a hormone. The hormone travels to the target cell where it brings about a physiological response. Helps restore pre-existing state.
