Posterior Pituitary ADH and Oxytocin Flashcards
Where are oxytocin and ADH made in the brain?
Oxytocin = paraventricular nucleus
ADH = supraoptic nucleus
What are the functions of oxytocin?
What are the functions of ADH?
Note that ADH has potent vasoconstriction properties. We usually think of angiotensin 2 as being most significant vasoconstrictor, but ADH actually more potent. Difference is probably half lives, ADH has short while Angio 2 is long.
True/false - the posterior pituitary is an endocrine gland.
False - it is not. It is a storage site for neurosecretions from the hypothalamus, which is an endocrine gland.
What are magnocellular neurons?
Non-myelinated axons that convey neurosecretory products to the pars nervosa (posterior pituitary) from the hypothlamaus
What is the function of pituicytes and herring bodies in posterior pituitary?
Pituicyte - glial cells (macrophages, clean up PostPit), also help the Herring bodies secrete their contents
Herring bodies - store the oxytocin and ADH, located near endothelial cells that line the blood vessels
The capillaries of the posterior pituitary blood supply are:
- Continuous
- Fenestrated
- Discontinuous
Fenestrated
Review the regulation of ADH as it pertains to osmotic pressure.
Remember - ADH responds to changes in osmolality becuase it only leads to the reabsorption of free water. Low osmolality = low osmotic pressure. High osmolality = high osmotic pressure.
Describe the feedback loop of oxytocin as it pertains to milk ejection.
Oxytocin stimulates the […] cells around the base of the alveolar secretory cells causing them to contract and eject milk.
Myoepithelial
Remember - mammary glands are modified sweat glands
Describe the effects of oxytocin on the uterus.
What signaling pathways do ADH and oxytocin utilize to carry out their effects on smooth muscle?
Bind to GPCRs (Gaq) –> stimulate PLC to cleave PIP2 into DAG and IP3 –> DAG acts as anchor for PKC and IP3 goes to sarcoplasmic reticulum to release more Ca2+ into cell –> activated PKC can phosphorylate important proteins and Ca2+ used for contractions (uterus, myoepithelial cells for oxytocin and vascular smooth muscle for ADH)
None - ADH is the pertinent hormone but it’s synthesized by hypothalamus not PostPit
VSMC, collecting duct of kidney, sweat glands
Increase water reabsorption, VSMC constriction, decrease sweat production
What is diabetes insipidus?
What are the 2 general causes?
What are the main causes of central diabetes insipidus?
Generally, what is the disease course for central diabetes insipidus? (3 phases)
What are the potential causes of nephrogenic diabetes inspidus?
Oxytocin
Mammary glands –> myoepithelial cells (also impacts uterine smooth muscle, but in this patient that’s less pertinent)
Signal via GPCR to increase Ca2+ and lead to contraction
What is sheehan’s syndrome?
What is Syndrome of Inappropriate ADH (SIADH)?
