Endo - Intro Flashcards
endocrine characteristics
secreted by specialized endo cells into blood
travel long distances
neuro-endocrine characteristics
product of neuron
released into blood
neural characteristics
product of a neuron
secreted into synaptic spaces
travels short distances
paracrine characteristics
secreted into extracellular space
diffuse short distances
autocrine characteristics
hormone secreting cell same as receptor containing cell
hormones : effects
usually more than one effect -
due to different target cells
or changes to effect based on developmental stage
peptide/protein hormone characteristics
encoded by DNA hydrophilic receptors on cell surface secondary messengers can be stored often circulate unbound
amine hormone characteristics
tyrosine derivatives hydrophilic receptors on cell surface secondary messengers *exception T3/T4
thyroid hormones characteristics not like amines
intracellular receptors
steroid hormone characteristics
llipophilic (non-polar) receptors in cytosol or nucleus derived from CHL w/ cyclopentano... ring (no DNA) not stored bound to specific globulin in blood long 1/2 lives
cross talk
may happen among hormone families
diff hormones bind to the same receptor
preprohormone actions
preprohormones are translated, partially then arrested by signal recognition complex that binds to signal peptides
the complex releases when it binds to a docking protein on the ER –> translation completes
–> prohormone
prohormone actions
prohormone is cleaved into active hormone in golgi
or prohormone is secreted and converted to active in ECF
active hormone secretion
packaged into secretory vesicles in golgi
await signal as membrane bound granules
exocytosed into blood stream
peptide hormone Tx route
not orally (inactivated by acid in stomach or peptidases in intestines) usually injected
groups of amine hormones
thyroid hormones
catecholamines
amine hormones from tyrosine
T3 = 2 tyrosine + 3 Is T4 = 2 tyrosine + 4 Is cats = modified tyrosines
catecholamine synthesis steps
tyrosine –> dopa –> dopamine –> NE –> E
catecholamine synthesis location
synthesis enzymes in cytosol
stored till secreted
types of steroid hormones
glucocorticoids mineralcorticoids vit D androgens estrogens progestogens
steroid sythesis
many enzymatic steps (many disorders possible)
cells only have enzymes for specific steroid to be made
steroidogenic enzymes
- side chain cleavage enzyme; desmolase
- 17 alpha-hydroxylase
- 21-hydroxylase
- aromatase
steroid metabolism
metabolized by cytochrome P50 in liver
excreted in urine or bile
1/2 lives can be very long (esp synthetic)
route of steroid hormone Tx
can be given orally
eicosanoid characteristics
derived from fatty acids (usually arachadonic acid)
released by lipases
act locally - paracrine
only active a few seconds (rapidly metabolized)
regulation of endocrine activity (broad)
rate of production*
rate of delivery (ex. blood flow)
rate of degradation (liver) and elimination (kidney)
chronotropic control
endogenous neuronal rhythm
based on diff external things (light/dark, eating, temp)
vary in time frame
may be diff @ diff life stages
pacemaker of circadian rhythms
suprachiasmatic nucleus
importance of pulsatile hormone release
maintains secretion of necessary hormones
continuous would inhibit other things or block production (down regulation of receptors)
binding proteins and half life
binding delays metabolism
provides reservoir of hormones
greater affinity to bps –> greater half life
hormone receptor characteristics
specificity (only certain hormones)
affinity (changed by conformation, down with high hormone levels)
density (up or downregulation –> de/sensitization)
permissiveness
one hormone in adequate amounts necessary for full effect of other protein to happen
synergism
combined effect is greater than sum
antagonism
one hormone lessens another hormone’s response
agonist
molecule binds to receptor
induces receptor to biological effect
(act like hormone - may be more or less potent)
antagonists
molecule binds to receptor
blocks agonist from binding
no biological effect occurs
