Magnocellular system: Vasopressin & Oxytocin

Question 1

PVN & SON

Answer 1

Secret Vasopressin and Oxytocin

Question 2

SON is responsible for _______ % of neurons producing AVP

Answer 2

80-90%

Question 3

PVN is more complex containing _________

Answer 3

Both AVP and OT

Question 4

True of False
During Resting state Hormones at the end of the Axon

Answer 4

True

Question 5

Hypothalamus is responsible for …

Answer 5

Hormone synthesis

Question 6

Synthesized as precursor molecules

Answer 6

nonapeptide (active hormone) + specific neurophysin + glycopeptide (AVP only)

Question 7

neurophysin

Answer 7

stabilizing protein, protein folding and is removed after ( cleaved during axon transport)

Question 8

Effects of Vasopressin

Answer 8

• Regulation of water: V2R in kidney- stimulated by osmoreceptors
• Vasoconstriction. dilation - V1R in blood vessels - stimulated by baroreceptors

Question 9

Baroreceptors

Answer 9

regulating blood pressure (Volume and diameter)

Question 10

Osmoreceptors

Answer 10

• increase blood osmolarity (dehydration)
• stimulates OsmoR in hypothalamus (AVP neurons) & Neurotransmitter at MC synapses
• both will activate AVP release from posterior pituitary
• V2R releases cAMP (second messenger) activating PKA to have AQP2 bind to membrane for reabsorption of water
• once their is enough, AVP stop releasing & execs water is let out through AQP3 and AQP4 into the interstitial space

Question 11

Short term response of osmoreceptors when you have high blood osmolarity

Answer 11

• Aqp2 translocation to apical cell membrane

Question 12

Long term response of osmoreceptors when you have high blood osmolarity

Answer 12

increased expression of Aqp2 and Aqp3 in principal cells

Question 13

Where are V2R located?

Answer 13

Kidney&raquo_space; collecting duct

Question 14

What type of hormone receptor does V2R use?

Answer 14

GPCR that uses GS alpha subunit&raquo_space; cAMP/PKA signaling pathway to stimulate water reabsorption

Question 15

Effects of Vasopressin

Answer 15

Regulation of water&raquo_space; V2R in kidney&raquo_space; stimulated by osmoreceptors

Vasoconstriction/ dilation&raquo_space; V1R in blood vessels» stimulated by baroreceptors

Question 16

What are baroreceptors?

Answer 16

Promote constriction, located in blood vessels

Question 17

Low Blood pressure

Answer 17

• stimulates baroreceptors in blood vessels
• signals to the brain (brainstem)
• neurotransmitters at the MC synapses
• AVP releases from posterior pituitary
• AVP bind to V1R causing vasoconstriction to increase blood pressure
• Once it has become regulated AVP release is stopped

Question 18

Carotid Sinus Receptors

Answer 18

takes blood into the brain

Question 19

Diabetes Insipidus

Answer 19

large volumes of urine but with no smell
can be cause by brain or kidney

Question 20

Consequence of AVPP deficiency with Diabetes Insipidus

Answer 20

can be caused by mutation that inactivates AVP - Neurogenic DI&raquo_space; lack of neurophysin 2
can be caused by mutations in the V2R or AQP2 genes - nephrogenic DI

Question 21

Brattleboro rat - AVP deficiency model

Answer 21

genetic mutation resulting inability to produce AVP
- Neurogenic (central) DI