Neuorhypophysial disorders

Question 1

Landmark on an MRI to indicate the posterior pituitary

Answer 1

Bright spot

Question 2

what is released from the neurohypophysial stystem

Answer 2

Vasopressin and oxytocin

Question 3

2 types of nuclei involved in the neurohypophysial system

Answer 3

Supraoptic and paraventricular nuclei

Question 4

Main effect of vasopressin

Answer 4

> Acts as anti-diuretic = increasing water reabsorption via V2 receptors

> Increase urine production

>ADH

Question 5

What structure does vasopressin mainly act upon

Answer 5

Renal cortical and medullary collecting ducts

Question 6

Draw / Outline the structure of a collecting duct (activation of PKA, AQP2)

Answer 6

Question 7

What area of the brain helps with the regulation of vasopressin

Answer 7

The organum vasculosum (contains osmoreceptors)

Question 8

How can the organum vasculosum effectively communicate with the systemic circulation

Answer 8

The structure is devoid of a blood-brain barrier (can sense the changes in plasma osmolality)

Question 9

Describe the action of an osmoreceptor

Answer 9

Sensitive to changes in the EC osmolality => Increase in EC Na+ => osmoreceptor shrinks => inrease in firing => vasopressin release from hypothalamic PVN/SON neuones