PHYSIOLOGY Flashcards
what is the general treatment for endocrine conditions
too much hormone = suppress it
too little hormone = stimulate/replace it
what is a hormone
a chemical messenger that travels in blood to a distant organ for a specific function
which type of gland secretes hormones into blood
endocrine glands
which type of glands secretes hormones into ducts
exocrine glands
which gland has both exocrine and endocrine components
pancreas
example of a protein (chain of peptides) hormone (1)
insulin
example of a peptide hormone (3)
ACTH
ADH
oxytocin
how are protein and peptide hormones made
cleaved from even long proteins
where are protein/peptide hormones cleaved
Golgi apparatus
where are protein/peptide hormones stored
vesicles
when are protein/peptide hormones released
when a signal is present
what is required for a protein/peptide hormone to be released from vesicles (as well as a signal)
Ca2+
do protein/peptide hormones need a carrier protein to be transported in the blood
why
no
they are hydrophilic so dissolve easy in plasma
are protein/peptide hormones stored or made on demand
stored
examples of steroid hormones (4)
cortisol
progesterone testosterone
oestrogen
are steroid hormones stored or secreted on demand
secreted on demand
from which molecule are endogenous steroids derived
cholesterol
do steroid hormones need a carrier protein to be transported in the blood
why
yes
they are hydrophobic so do not dissolve in plasma
what is albumin
a carrier protein for steroids and thyroxine
what is cortisol binding globulin
a carrier protein for cortisol
what is the carrier protein for testosterone and oestradiol
sex steroid binding globulin
why cant steroid be permanently bound to carrier proteins
bc they need to be ‘free’ (unbound) to go across the membrane of cells (including the bladder when getting eliminated)
what type of receptor is a steroid hormone receptor (glucocorticoid receptor GR)
where is it
class 1 nuclear receptor
in the cell cytoplasm - not on the cell surface
what happens when the steroid binds with its receptor (receptor steroid complex)
receptor-steroid complex binds to DNA and affects mRNA or rate protein synthesis
if the receptor-steroid complex binds with a GR (glucocorticoid receptor) DImer what happens
RNA transcription
if the receptor-steroid complex binds with a GR (glucocorticoid receptor) MONOmer what happens
no RNA transcription
apart from glucocorticoid receptors (GR), what other type of receptors can steroids bind to
mineralocorticoid receptors (MR)
examples of modified amino acid hormones (4)
adrenaline
thriiodothronine T3
thyroxine T4
melatonin
how are modified amino acid hormones made
from tyrosine/tyramine
are modified amino acid hormones stored or secreted on demand
stored
what is needed for the release of modified amino acid hormones from vesicles as well as a signal
Ca2+
which modified amino acids are hydrophobic and require carrier proteins to transport them in blood
thyroxine T4
triiodothyronine T3
carrier proteins for thyroxine (3)
thyroxine binding globulin (TBG)
albumin
transthyretin
paracrine signal definition
chemical communication between cells within a tissue or organ with no circulation involved (different form both autocrine and endocrine)
autocrine signal definition
chemical that acts on the same cell it was produced from
opposite of endocrine signal
endocrine signal definition
chemical that acts on a different and distant cell to the cell that produced it
opposite of autocrine signal
what is the feedback mechanism of hormones
negative feedback
why is negative feedback important for hormones
to maintain normal plasma levels of the hormone
the presence of which hormone inhibits corticotrophin release from the hypothalamus
cortisol
what can increase cortisol levels
stress
how are hormones eliminated
kidneys and liver
where are G protein coupled receptors
cell membrane
what is the hormone receptor for insulin
receptor tyrosine kinase
where are receptor tyrosine kinases found
cell surface
what do receptor tyrosine kinases respond to
example
protein and peptide hormones (eg insulin)
which part of the tyrosine kinase receptor does insulin bind to
alpha subunit
when insulin binds to the alpha subunit of receptor tyrosine kinase, what happens
autophosphorylation of beta subunit
autophosphorylation of beta subunits in receptor tyrosine kinase results in…
phosphorylation of insulin receptor substrate proteins = cellular effects
what type of receptor does growth hormone and prolactin bind to
cytosine receptor
what activates class I nuclear receptors
steroids
what activates class II nuclear receptors
lipids
what activates class I/II hybrid nuclear receptors
thyroid hormones
what is important about the hormones that activate nuclear receptors
why
they must be lipophilic to diffuse across the cell membrane
what hormones activate g protein coupled receptors (3)
proteins
peptides
calcium??
how many times does a g protein coupled receptor cross the membrane
7
what hormone activated a tyrosine kinase receptor
insulin
what hormone activates a cytosine receptor (2)
growth hormone
prolactin
what hormone activates a cytosine receptor (2)
growth hormone
prolactin
what 6 hormones does the anterior pituitary secrete
GH prolactin ACTH FSH LH TSH
what 2 hormones does the posterior pituitary secrete
ADH
oxytocin
what 3 hormones does the thyroid gland secrete
T3 triiodothyronine
T4 thyroxine
calcitonin
what hormone does the parathyroid glands secrete
PTH
what 2 endocrine hormones does the pancreas secrete
insulin
glucagon
what 2 hormones does the adrenal cortex secrete
glucocorticoids
aldosterone
what 2 hormones does the adrenal medulla secrete
adrenaline
noradrenaline
