Hypothalamus/Pituitary Flashcards
In prediabetes, oxytocin increases peripheral glucose uptake by a ________ mechanism, but not via the insulin receptor pathway
GLUT-4
During intraaxonal transport of precursor ADH and oxytocin, what is it cleaved into?
ADH/ oxytocin
Neurophysin
terminal glycoprotein
Is BNP more abundant in the ventricle or atria
ventricle
Where are ADH and oxytocin synthesized
hypothalamic neuronal cell bodes (magnocellular neurons)
What are the neurons involved in signal transmission from hypothalamus to anterior pituitary
Parvicellular neurons
ADH binds to which neurophysin?
Oxytocin bind to which neurophysin?
ADH = NP 2 oxytocin = NP 1
ADH and oxytocin are co-secreted with
neurophysins
Is oxytocin more abundant in the ventricle or atria
3-4x more abundant in the atria
What are the neurons involved in signal transmission from hypothalamus to posterior pituitary
magnocellular neurons
How are ADH and oxytocin transported?
in axons with neurophysins
Oxytocin regulates cardiac function by modulating the ____________ system and inotropicity
parasympathetic
Releasing hormones regulate the secretion of ____________ from cell types of the anterior pituitary
tropic hormones
What is the role of neurophysin?
carrier proteins that prevent diffusion of hormones (oxytocin and ADH) out of axons
A decrease in blood volume of _____% elicits an increase ADH release
8-10%!!
Magnocellular neurons of the hypothalamus project their axons down the ___________ and terminate in the _________ where they release their hormones into a _________
infundibular process
posterior lobe
capillary bed
Is ANP more abundant in the ventricle or atria
more abundant in the atria
What is the effect of oxytocin in the peripheral arterioles
oxytocin induces NO-dependent vasodilation, decreasing BP and resistance to blood flow.
What is the plasma half-life of ADH and oxytocin
short! ~ 8 min
The result of ADH release is an increase in _____ and a decrease in ______ with low urine output
plasma volume
osmolarity
Oxytocin effects on blood pressure:
Oxytocin is released from the posterior pituitary into the plasma, where it can bind to receptors in the:
vasculature
kidney
cardiac tissue
What are the two types of oxytocin that exist in the heart
pituitary oxytocin
local oxytocin
In cardiac muscle, oxytocin binds to receptors resulting in:
synthesis and release of ANP and NO
negative inotropic and chronotropic effects
Oxytocin stimulates _____, _______, ______ and _____via RENAL oxytocin receptors
diuresis
natriuresis
kaliuresis
decreased plasma volume
ADH targets the kidney by acting on a ____ receptor
v2
Hormones of the Posterior pituitary
oxytocin arginine vasopressin (ADH)
Other than plasma osmolarity, ADH release can be stimulated by
a decrease in blood volume or blood pressure
not as sensitive!
Small changes in plasma osmolarity above a threshold of __________ mOsm/L produce an increase in ADH release before stimulation of _______
280-284
thirst
What classification of hormone are the two hormones of the posterior pituitary (oxytocin and ADH)
neuropeptides
ADH acts on the _____ receptor to induce vasoconstriction
V1
Activation of peripheral aortic baroreceptors in response to stimuli (blood volume, HTN, etc) within the ____________________ results in activation of the _________________ which in turn induces synthesis of ________________ in the hypothalamic parvicelluar neurons (PVN) and supraoptic nuclei (SON)
nucleus tractus solitarius (NTS)
oxytocinergic neurones (Otn)
Oxytocin (OT)
Increased levels of plasma oxytocin (or increased OTn) results in a reduction of _______ which leads to a decreased production of ________
corticotropin RF (CRF) cortisol
Hormones of the anterior pituitary
ACTH (adrenocorticotropic hormone) GH (growth hormone) TSH (thyroid-stimulating hormone) PRL (prolactin) LH (luteinizing hormone) FSH (follicle-stimulating hormone)
Parvicellular neurosecretory neurons of the hypothalamus project axons to the ________ where they secrete _____ which flow down the pituitary stalk in the hypothalamo-hypophyseal portal vessels to the _____`
median eminence
releasing hormones
anterior pituitary
Oxytocin causes ANP/BNP release fro cardiomyocyte and _____, in turn, stimulates the release of ________
ANP
nitric oxide from vascular endothelium
Oxytocin’s vasodilatory effect on peripheral arterioles through NO is enhanced in the presence of
estrogen
