5.4 hormonal communication Flashcards
define endocrine system
communication system that uses hormones as signalling molecules
made of endocrine glands
define hormones
cell signalling molecules produced by endocrine glands and are released into the blood
travel to target cells and bind to receptors
how does a hormone work
travels to a target cell and binds to specific receptors
initiates a response
name the types of hormone
protein
steroid
how do protein hormones work
aren’t fat soluble so do not enter the cell
need to bind to receptors on the cell surface membrane
release second messenger into cell
how do steroid hormones work
are fat soluble
can enter cell and nucleus
have direct effect on DNA
what do endocrine glands do
release hormones into the blood
no ducts
what do exocrine glands do
release into ducts
what are first messengers
non steroid hormones (protein)
signalling molecules that bind to csm and initiate an effect inside cell (cause release of second messenger)
what are second messengers
stimulates change in activity of cell / reaction
what is the adrenal gland
(endocrine glands)
a pair of glands lying above the kidney which releases adrenaline (and other hormones)
what are the adrenal glands made up of
adrenal cortex (outer layer)
adrenal medulla (inner layer)
what is adrenaline
protein hormone that is released from adrenal glands
stimulates body to prepare for fight or flight response
functions of adrenaline
relax smooth muscles in bronchiole
increase SV, HR
vasoconstricts to increase bp
stimulates conversion of glycogen to glucose
dilates pupils
increases mental awareness etc
hormones released from adrenal cortex (3)
mineralocorticoids
glucocorticoids
cortisol
functions of hormones from the adrenal cortex
mineralocorticoids - control leels of Na and K in the blood, maintain blood pressure
glucocorticoids - metabolism of carb, fats, and proteins in the liver
cortisol - stress hormone, can be taken up by ovaries or testes to make sex hormones
hormone released from the adrenal medulla (1)
adrenaline
describe the function of the pancreas
endocrine - secretes hormones into the blood capillary
exocrine - synthesise and release digestive enzymes
describe how the pancreas works as an exocrine gland
secretes substances into a duct
synthesise and release digestive enzymes
exocrine cells are in a small group of cells surrounding tubules - acinus
these cells secrete enzymes they synthesise into the tubule
describe what enzymes are produced by the pancreas for the exocrine function
protease = trypsinogen - inactive protease conerted into trypin in the duodenum
amylase
lipase
describe how the pancreas works as an endocrine gland
secrete hormones into the capillary
made of Islets of langarhan
islets contain alpha and beta cells = endocrine tissue
what do alpha and beta cells produce
alpha - produces glucagon
beta - produces insulin
how is insulin released from beta cells
normal blood glucose levels = K+ ion channels are open, Ca+ ion channels are normally closed
potassium diffuses out = cell more negative
high glucose levels = glucose moves into the cell (facilitated diffusion) = metabolised to produce ATP
ATP causes causes potassium channels to close
K+ no longer diffuses out and causes cell inside to become less negative
change in potential difference causes Ca+ ion channels to open
Ca+ ions open and Ca+ enter
causes vesicles of insulin to fuse with the membrane and release insulin out of the cell by exocytosis
effect of insulin
more transporter proteins specific to glucose are placed in c.s.m
more glucose enters cell
glucose in cell is converted to fats/glycolysis/used in respiration
