Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Endocrinology > Hypothalamo-neurohypophysial system > Flashcards

Hypothalamo-neurohypophysial system Flashcards

1
Q

What is the neurohypophysis made of?

A

nerve axons that pass down from the pituitary stalk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the suprachiasmatic nucleus?

A

vasopressinergic neurones originate here

location of biological clock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are magnocellular neurones?

A 
cell bodies in paraventricular/supra optic nucleus
terminate in neurohypophysis
large long axons 
to posterior pituitary 
vaso/oxytocinergic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are parvocellular neurones?

A 
cell bodies in PV nuclei
terminate in median eminence and other parts of brain
average, short axons 
to anterior pituitary
vaso/oxytocinergic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What neurones are found in the paraventricular nuclei?

A

parvocellular and magnocellular neurones
parvocellular produce CRH and vasopressin
most magnocellular and terminate in NH
some are parvocellular and terminate in ME

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What neurones are found in the supraoptic nuclei?

A

all magnocellular neurones

pass through ME and terminate in NH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are Herring bodies?

A

areas where neurosecretions are stored on way down to neurohypophysis
specific to magnocellular neurones of PV and SO nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why are neurosecretions hormones?

A

they are released into the general circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What 2 hormones are both released from paraventricular neurones?

A

CRH and vasopressin from parvocellular neurones terminating in ME and travel down pituitary portal system into pituitary corticotrophs
both secreted at same anatomical location

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does CRH need to effectively stimulate ACTH release?

A

vasopressin

vasopressin is not an ACTH secretogogue on its own

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a secretogogue?

A

a substance that promotes secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What generates pre-provasopressin?

A

nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does signal do to pre-provasopressin?

A

directs it to the axons where it forms a pro-hormone

pre-provasopressin splits in 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to pre-provasopressin?

A

converted to pro-hormone –> vasopressin + neurophysin + glycopeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is AVP?

A

arginine vasopressin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is neurophysin?

A

large molecule (protein) specific to provasopressin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is GP ?

A

glycopeptide

= a prolactin releasing factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the difference with oxytocin compared to vasopressin production?

A

different neurophysin produced and no glycopeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens to vasopressin pro-hormone?

A

passes along neurone in Herring bodies
neurophysin bound gives stability and prevents hormone diffusing out of Herring body and being degraded by enzymes
at end of neurone the pro hormone is cleaved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the differences in structure of vasopressin and oxytocin?

A

AVP has Phenylalanine not isoleucine
AVP has arginine instead of leucine
DIFFER BY TWO AMINO ACIDS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What vasopressin do some animals have?

A

lysine instead of arginine

22
Q

What are the similarities between vasopressin and oxytocin?

A

nonapeptides

both synthesised as pro hormones which as cleaved to form hormone and neurophysin protein

23
Q

What is the effect of vasopressin on renal collecting ducts?

A

stimulate water reabsorption

anti diuretic effect

24
Q

What is effect of vasopressin on blood vessels?

A

vasoconstriction

VP released by parvocellular neurones in ME and acts with CRH to control corticotrophin release

25
What is the effect of VP on CNS?
acts as hormone/NT affecting behaviour
26
What is the effect of VP on synthesis of blood clotting factors?
involved in clotting factors VIII and VWF | analogues of VP and VP used to treat blood clotting disorders
27
What is the effect of VP on hepatic glycogenolysis?
VP released by stressors (dehydration) | increases blood glucose
28
Where are V1a VP receptors?
most important in vasculature, brain mainly arterial/olar smooth muscle - vasoconstrict hepatocytes - glycogenolysis CNS neurones - behavioural and other effects
29
Where are V1b VP receptors? (V3)
adenohypophysial corticotrophs (ACTH production)
30
Where are V2 VP receptors?
collecting duct cells - water reabsorb endothelial cells - vasodilation factor VIII and VWF
31
How does a V1 receptor work?
``` Gq protein linked receptor protein is linked to phospholipase C PLC activated convert PIP3 to IP3 and DAG these both increase [Ca] cytoplasm activate protein kinase C ```
32
How does a V2 receptor work?
``` Gs protein linked receptor linked to adenylate cyclase AC activated convert ATP to cAMP activated PKA this activates other intracellular mediators that produce cellular responses - recruit aquaporins to cause ADH effect ```
33
How to hormones affect the brain?
if enter CSF
34
How does vasopressin work in the principal cells?
1. V2 receptors on basolateral membrane bind to VP and activate AC 2. AC converts ATP --> cAMP 3. cAMP activated PKA 4. stimulates AQP2 synthesis 5. AQP2 needed to move water across cell membrane 6. AQPs assemble into accumulations called aggraphores 7. VP causes these to migrate to apical membrane (face inside of collecting duct) 8. Water moves into cells via AQP2 9. Water moves out of cells by AQP3 and 4
35
What are the principal cells?
collecting duct cells
36
How many different AQPs are there?
9 | AQP2 is VP dependent
37
What is needed to move water from collecting duct --> principal cells --> blood?
osmotic gradient
38
How is VP controlled? | 1. stimulus = dehydration
1. increase in plasma osmolarity detected by osmoreceptors 2. stimulate vasopressinergic neurones to release VP 3. more water reabsorbed and osmolarity returns to normal 4. stimulus removed 5. VP switched off
39
What must osmoreceptors be in contact with?
vasopressinergic neurones in order to stimulate them | osmoreceptors are also in the blood and so lie outside the blood brain barrier (circumventricular organs)
40
How is VP controlled? | 2. ?
Influence from higher centres - stress - surgery - anaesthesia
41
How is VP controlled? | 3.?
1. fall in arterial BP detected by baroreceptors 2. activity of baroreceptors is reduced - removal of tonic inhibition of VP release 3. baroreceptors decrease activity 4. decreased inhibition 5. increase VP release 6. increase sympathetic activity (baroreceptors linked to SNS to control vasoconstriction) 7. increase vasoconstriction --> increase BP
42
What are baroreceptors?
stretch receptors that detect increase pressure
43
What happens normally to VP?
tonic inhibition of VP release
44
What is oxytocin?
a contractor hormone -cause constriction
45
What is the central effect of oxytocin?
behavioural
46
What is the effect of oxytocin on the uterus at parturition?
``` increased stress on uterine wall causes release of oxytocin acts on smooth muscle receptors on myometrial cells contraction facilitates delivery ```
47
What is the effect of oxytocin on the breast during lactation?
prolactin stimulates milk production NOT EJECTION ducts/alveoli that produce milk surrounded by contractile myoepithelial cells that have myoepithelial receptors suckling --> stimulate oxytocin release --> myoepithelial cells contract --> milk ejection
48
What is the difference between prolactin and oxytocin?
act via same afferent pathway (detection of suckling) one arc goes to adenohypophysis to stimulate prolactin production whilst the other goes to neurohypophysis to stimulate production of oxytocin
49
What is diabetes insipidus?
central diabetes insipidus - no VP produced nephrogenic DI - tissue insensitivity present with polydipsia, polyuria
50
What is SIADH?
too much ADH produced decrease plasma osmolarity urine is very concentrated

Endocrinology (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions