Jan30 M1-Control Systems Flashcards
4 components of a control system (with feedback loop)
control centre, effector, regulated variable, sensor
4 components of control in the control of thyroid hormone conc
control centre: pituitary
effector: pituitary makes TSH, stimulates thyroid to make TH.
variable: thyroid hormone conc
sensor: pituitary
PSS main nerve and effect on bladder, liver, GI, lungs, heart, saliva
vagus. heart slower. bronchi constrict. bladder contracts. peristaltism and secretion. flow of saliva. secretion of bile
SS gland that helps its effect + effect on pupils, saliva, GI, liver, medulla and bladder
adrenal gland. dilates pupils, less saliva, less peristaltism+no secretion, conversion of glycogen to glucose (liver), NE and E by medulla, bladder relaxation
hormone def
molecular mediator of intercellular information transfer
streams hormone can take to go act on other site
bloodstream, synaptic cleft, interstitial space, adjacent cell, same cell
autocrine vs paracrine vs endocrine
endocrine = goes in blood paracrine = neighboring cell autocrine = acts on cell that secretes it
diff modes of action of hormones on a cell and examples
- plasma membrane receptor (can’t get through membrane) = peptide hormone
- cytoplasmic (and then nuclear) or nuclear receptor. ex: steroid hormone
6 peripheral endocrine glands
- thyroid and parathyroid
- thymus
- adrenal glands
- pancreas
- ovary or testis
what acts on the peripheral endocrine glands
pituitary gland and pituitary hormones
what acts on pituitary and how
hypothalamus releasing factors. released in portal pituitary blood vessels
endocrine neuron def and example
neuron that secretes hormone. ex. hypothalamus neuron with axon extending to posterior pituitary and secreting oxytocin and ADH there
what acts on hypothalamus
brain neurotransmitters
how feedback works in endocrine system (HP axis)
circulating hormones made by peripheral glands act on peripheral glands, pituitary and hypothalamus to feedback.
ways messages are transmitted in HP axis (endocrine system)
brain to H: nts via axons and synapses
H to P: releasing factors via hypothalamo-hypothyseal portal system
P to peripheral endocrine: pituitary hormones, general circulation
peripheral endocrine: hormones, circulation
HP axis hormones on thyroid
TRH (TSH releasing hormone) and TSH (thyroid stimulating hormone)
HP axis hormones for growth
GRF (GH releasing factor) (+) or somatostatin (-)
GH in pituitary
HP axis for gonads
Gonadotropin releasing H (GnRH)
FSH (follicle stimulating hormone)
LH (luteinizing hormone)
HP axis on adrenals
CRF (corticotropin releasing factor)
ACTH (Adrenocorticotropic H)
HP axis on mammary gland
dopamine from H INHIBITS release of prolactin of pituitary
how to check thyroid function clinically and why
TSH levels because t3 and t4 bind to proteins
TSH levels meaning
high TSH = hypothyroidism
low TSH = hyperthyroidism
hypothalamus to posterior vs to anterior pituitary: mode of hormonal messaging + explanation
posterior = neurotransmitter (neuron only) anterior = neuroendocrine (hormone to blood) endocrine = cell to blood (pancreas, adrenal)
two modes of hormonal communication of hypothalamus
- neurotransmitter (produces and releases in posterior pituitary ‘‘region’’)
- neuroendocrine (TRH release to portal blood system, TRH reaches cell. TSH already produce in anterior pituitary released by anterior pituitary in response to TRH in portal blood
estrogen effect on HP axis
can have positive or negative effect on pituitary (pituitary produces and releases FSH and LH)
FSH and LH effects in male
LH stimulates production of testosterone
FSH stims prod of sperm (by supporting Sertoli cells)
other name for cortisol
stress hormone
only pituitary hormone that is regulated by negative feedback alone and which feedback
prolactin. dopamine’s negative feedback
only HP axis hormone that is not a peptide hormone and what it is
dopamine (from H): is derived from an a.a
effect of high prolactin on mammary gland
development and milk production
effect of high prolactin on gonads
inhibits GnRH so FSH and LH are not produced (natural contraceptive when mother producing milk)
pathologic state where high prolactin and name and possible consequence
prolactinoma (pituitary tumor)
can cause infertility bc inhibits GnRH
effect of sucking stimulus on the breast
spinal afferents act on hypothalamus and less dopamine released so more prolactin production and release
exogenous factors that can increase prolactin and cause contraceptive effect or infertility
some tranquilizers in psychiatry like antidepressants, tranquilizers and alpha-methyl-dopa (dopamine antagonists) less dopamine = more prolactin
other name for ADH or vasopressin
AVP (arginine-vasopressin)
how hypothalamus can sense the need to produce and release AVP + other stimulus for ADH release
osmoreceptors on it
blood volume is also a stimulus for ADH release
if 100L filtered daily in the glomerulus, how much reabsorbed if AVP active (rest of nephron vs collecting duct)
85 L before CD
15 L at collecting duct
all 100L reabsorbed
exogenous stimuli on vasopressin secretion (2)
alcohol inhibits it (beer makes you pee)
nicotin stimulates ADH
oxytocin stimulus to release and functions (2)
baby sucking nipple stimulates oxytocin release
oxytocin stimulates SM for milk release and uterine contractions
what adrenals produce in response to ACTH
cortisol
what ovary and testis produce in response to FSH and LH
testoserone and inhibin
progesterone, estrogen and inhibin
magnocellular vs neuroendocrine
magnocellular is neuroendocrine but is hypoth neuron that has axon extending in posterior pituitary secretes stuff there (as if it comes from post pit)
neuroendrine = neuron secretes hormone in blood
what hormones secreted in pulsatile fashion + meaning
GnRH and therefore FSH, LH and progesterone and estrogen. means secreted at fixed interval
why GnRH might be released in pulsatile fashion
frequency might be what determines if it’s rather FSH or LH that is stimulated
only non peptide hormone of HP axis and type of molecule
dopamine. is an amide (a.a derivative)
stimuli to GnRH release in males and females (4 ex)
visual, olfactory, pineal, stress
how ovaries feedback in response to FSH and LH
- progesterone and estrogen neg feedback on pituitary and hypothalamus
- inhibitn neg feedback on pituitary
how testes feedback in response to FSH and LH
- testosterone neg feedback on pituitary and hypothalamus
- inhibin neg feedback on pituitary
ACTH function
stimulates adrenal cortex to make cortisol
2 influences on hypothalamus in HP-adrenal axis
circadian rhythm, stress
how adrenal cortex feedbacks in response to ACTH
-cortisol neg feedback on hypoth and pit
molecule that stimulates pit hormone to make ACTH, other than CRF
epinephrine
condition where AVP (ADH)’s action on CTs doesn’t work and consequence
diabetes insipidus. 14L water reabsorbed daily in CT is secreted
oxytocin feedback loop
positive feedback. suckling on nipple = stimulated prod of oxytocin by hypoth neurons via afferent impulses
