Endocrinology- Exam 1- Posterior Pituitary

What is another name for the pituitary gland?

Hypophysis

What is another name for the posterior lobe of the pituitary?

What is another name for the anterior lobe of the pituitary?

NBQ

-Neurohypophysis

-Adenohypophysis

T/F: the posterior pituitary produces ADH and oxytocin. TQ

FALSE: it stores and secretes these! It does NOT make any hormones!!

What is the role of the anterior lobe of the pituitary gland?

receive signals from the hypothalamus to make and secrete 7 important hormones (trophic hormones)

What is the name of the area between the hypothalamus and the pituitary gland?

Infundibulum

What is the inferior portion of the posterior pituitary called?

What is the superior end called?

-median eminence

-infundibulum/pituitary stalk

Are the axons that pass down from the hypothalamus to the infundibulum (superior) end of the posterior pituitary myelinated or non-myelinated?

non-myelinated

What is the pathway from the Hypothalamus to the Posterior Pituitary? Long card

hormones in hypothalamus-> travel down non-myelinated axons-> stored in nerve terminals of the post. pituitary-> once stimulated, neurosecretory vesicles are released from the post. pituitary and secreted into blood

What are the two hormones that are produced by the hypothalamus?

Which nuclei produces each?

TQ

-Oxytocin (paraventricular nuclei)

-ADH (supraoptic nuclei)

Oxytocin and ADH are both considered what type of hormones?

Peptide Hormones

Where does ADH/Vasopressin primarily act and what is its effect?

acts on collecting ducts of kidney to facilitate reabsorption of water into blood

What is unique about Oxytocin?

one of the few hormones involved in creating a positive feedback loop (labor/delivery)

When would we need to release of ADH/Vasopressin? (2) TQ

1. Decrease in Blood volume or low BP

2. Increase in blood osmolarity (dehydration)

What senses decrease in blood volume/low BP ?

baroreceptors

What senses blood osmolarity?

osmoreceptors

Where, SPECIFICALLY, does ADH act on the target tissue?

principal cells of the collecting ducts (of nephrons in the kidney)

What is the secondary effect of vasopressin (ADH) and when would we see this effect taking place? TQ

-vasoconstriction

-during rapid blood loss (ex: hemorrhaging) to help maintain increased blood pressure

Which ADH receptor utilizes the adenylyl Cyclase mechanism (cAMP)?

V2 receptor (kidneys)

which ADH receptor utilizes the phospholipase C mechanism (IP3, DAG, Ca2+)?

V1 receptor (vascular smooth muscle)

T/F: ADH concentrates sodium and waste products in the urine.

TRUE

ADH causes reabsorbing of water into the blood. This does what to blood volume and blood pressure?

What does it do to urine concentration?

TQ

-increase blood volume

-increase BP

-increase urine concentration (less diluted w water)

What are VRAs and what do they do?

Vasopressin receptor antagonists; block the action of ADH/Vasopressin

What population would likely be on a VRA (vasopressin receptor antagonist)?

Those with congestive heart failure, hyponatremia (low sodium in blood), liver cirrhosis and SIADH

What occurs during central diabetes insipidus?

What can this be caused by? TQ

-decreased output of ADH

- insufficient hypothalamus release, and/or trauma to pituitary

What are the physical characteristics of central diabetes insipidus? (think what hormone is depleted and the effects of this!) TQ (4)

1. Polyuria (can't hold urine)

2. Dilute urine

3. hypotension (decreased plasma volume)

4. Increased plasma concentration

In central diabetes insipidus (CDI), what is one way that the body tries to compensate for the lack of ADH?

Increasing aldosterone

In CDI compensation, aldosterone is produced from the _______________ ___________ and is released. This causes __________________ renal reabsorption of __________.

adrenal cortex; increase; sodium

Aldosterone increases reabsorption of water and electrolytes in the kidneys how?

increases renal reabsorption of sodium, excretes hydrogen and potassium ions

Overall, when the body compensates for CDI by secreting aldosterone, what happens to blood volume and blood pressure?

What happens to blood osmolarity?

-both increase

-osmolarity decreases