Lecture 12: The HP unit Flashcards
what 2 structures meet to form the pituitary
Rathke’s pouch + Infundibulum process
what is the source of melanocyte stimulating hormone (MSH)
pars intermedia of pituitary
what is the target of vasopressin
collecting ducts of kidney
what is the effect of vasopresson in the kidney
- increases number of aquaporins in CD
- increases water reabsorption by CD
- decreases urine production = antidiuretic
what are the 2 sitmuli for vasopressin release
Osmoreceptors in hypothalamus (mainly)
decreased stimulation of carotid and aortic stretch receptors (important for large acute changes in blood volume)
what two places are V2 receptors found within the kidney
distal tubule and collecting duct
when vasopressin binds V2, it activates what pathways
Cyclic AMP (cAMP)
increases the permeability of the luminal membrane to water by inserting new aquaporin water channels
water enters cells from lumen , and then back into blood
when there is a dramatic loss of blood, ____ receptors present in vascular smooth muscle tissue are stimulated to recover blood pressure
V1A
what are the 2 stimuli that vasopressin responds to
- increased blood osmolality
- decreased blood volume
Central (neurogenic) Diabetes Insipidus often occurs as a result of…
a
a head injury that results in disease or damage to ADH neurons
Central (neurogenic) DI physiological symptoms
- deficiency of vasopressin release (low serum VP)
- collecting ducts impermeable to water
- large volumes dilute urine
- body fluids become concentrated
what is the treatment for Central DI
Exogenous vasopressin or synthetic analogues (dDVAP)
In Nephrogenic DI, the collecting ducts are ___________ to VP
non-responsive
there is a defect in V2 receptor, G-protein or intracellular signaling
physiological effects of Nephrogenic DI
- water not reabsorbed, large volumes of dilute urine
- body fluids concentrated
- VP release is elevated, serum VP high
possible txt for Nephrogenic DI
- Thiazide diuretics decrease renal filtration (GFR) and decrease Na reabsorption in distal tubule
what is Syndrome of Inappropriate ADH (SIADH) a result of
- VP being released from an autonomous source (like a tumor)
- VP regulation not under inhibitory feedback control
Symptoms of SIADH
- Hyponatremia (low serum Na, high urine Na)
- reduced serum osmolarity
- confusion, disorientation
- generalized muscle weakness, tremors, ataxia
- seizures and coma
how can you test to differentiate b/w central or nephrogenic diabetes in a patient
VP response test
- specific gravity peaks in animals w/ primary VP deficiency
- but shows little change in animals w/ nephrogenic DI
treatment for SIADH
- Hypertonic saline
- diuretics
- V2 antagonists (demeclocyline, conivaptan, tolvaptan)
- fluid restriction
oxytocin promotes…
- parent offspring bonidng
- mate bonding in monogamous species
- social cohesion
- ensures delivery of term fetus
- milk release during lactation
- transport of sperm
physiological effects of oxytocin in relation to reproduction
- strengthens uterine contractions at end of pregnancy
- milk release during nursing
- sperm transport in female reproductive tract
f
Behavioral functions of oxytocin in relation to reproduction
- maternal offspring bond
- mate bonds
what are the non-reproductive effects of OT
- slows heart
- reduced bp and its force of contraction by stimulating ANP
what is the role of OT in birth
- labor is initiated when uterine oxytocin receptor concentration reaches a critical threshold
- *positive feedback cycle *increases until cervical dilation and devliery of baby complete
OT and milk-let down demand
- suckling/milking causes paraventricular cells to release OT via posterior pit. into blood stream
- myoepithelial cells contract which moves milk into ducts and cistern
- milk let down
+ feedback mechanism
