Hypothalamus-Pituitary Relationship Flashcards

1
Q

What are the nuclei of the hypothalamus?

A
PVN (Paraventricular Nucleus)
POA (Preoptic Nucleus)
ARC (Arcuate Nucleus)
SCN/SC (Suprachiasmatic Nucleus)
SON (Supraoptic Nucleus)
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2
Q

What is the median eminence?

A

The floor of the hypothalamus and the convergence point for axons

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3
Q

What are some general hypothalamic functions and the associated nuclei?

A
Sleep - SCN
Feeding behavior/Satiety - ARC
Thirst - PVN
Reproduction - POA
Circadian Rhythms - SCN
Mood/Emotions/Stress - PVN/ARC
Body Temp - POA
Blood Pressure - PVN
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4
Q

What are some important hypothalamic releasing hormones?

A
GnRH (inhibited by GnIH)
CRH
TRH
GHRH
Somatostatin
Dopamine
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5
Q

What do the hypothalamic releasing factors target?

A

the anterior pituitary

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6
Q

Discuss the type, origin, target, second messengers, and function GnRH

A
Peptide hormone (10AA)
The brain nuclei are scattered, but the POA has majority
Gonadotropes - FSH and LH
IP3/DAG/PKC (via GPCR)
Reproduction
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7
Q

Discuss the type, origin, target, second messengers, and function of CRH

A
Peptide (41AA)
PVN
Corticotrope - ACTH
cAMP
Glucocorticoids - Pleiotropic effects
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8
Q

Discuss the type, origin, target, second messengers, and function of TRH

A
peptide (3AA)
PVN
Thyrotrope - TSH
IP3/DAG/PKC
Thyroid Hormone - pleiotropic effects
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9
Q

Discuss the type, origin, target, second messengers, and function of GHRH

A
peptide (44AA)
ARC
Somatotrope - GH
cAMP
Growth and development
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10
Q

Discuss the type, origin, target, second messengers, and function of somatostatin

A
peptide (14AA)
periventricular (PeVN)
Somatotrope
cAMP
Inhibits GH
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11
Q

Discuss the type, origin, target, and function of dopamine

A

amine
ARC
Lactotrope - prolactin
Milk production

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12
Q

Discuss Kallman’s syndrome

A

genetic disease where neurons fail to enter the CNS
characterized by sterility and anosmia
X-linked: Kal1
autosomal: Kal2

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13
Q

Describe the hypophyseal portal system

A

vascular connections between the hypothalamus and pituitary gland

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14
Q

Describe the connections of the hypophyseal portal system

A

the anterior pituitary axons release hormones into the superior hypophyseal artery which carries them to the anterior pituitary

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15
Q

What is the importance of hormone pulsatility?

A

Can help in the sensitization problem

TSH, FSH, LH, hCG all require the common subunit alpha-glycoprotein subunit (alpha-GSU): Pulse frequency can determine which subunit & subsequent hormone is released

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16
Q

What are the two major pathways of the hypothalamic-pituitary connection?

A

Tuberoinfundibular system

Neurohypophyseal tract

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17
Q

Discuss the tuberoinfundibular system

A

Comprises all neurons that send projections to the median eminence - they have a portal system

Hormones target the anterior pituitary via the capillary system (endocrine)

18
Q

Discuss the Neurohypophyseal tract

A

comprises neurons whose axons terminate in the posterior pituitary - does NOT have a portal system

19
Q

What are the different anatomical landmarks of the anterior pituitary?

A
Pars distalis (90%)
Pars intermedia
Pars tuberalis
20
Q

What are the different anatomical landmarks of the posterior pituitary?

A

Pars nervosa

Infundibulum (stalk)

21
Q

What is another name of the anterior pituitary and what kind of tissue is it made up of?

A

Adenohypophysis

made up of glandular tissue: cords of epithelial cells

22
Q

What is another name for the posterior pituitary and what kind of tissue is it made up of?

A

Neurohypophysis

made up of neural tissue: terminal axons and glial cells

23
Q

What is the blood supply of the posterior pituitary?

A

via inferior hypophyseal artery - has it’s own capillary bed, does not use a portal system

24
Q

From where do the axons that terminate in the neurohypophysis originate?

A

Magnocellular axons

25
Q

What are the major hormones of the neurohypophysis?

A

Arginine vasopressin (AVN) and oxytocin (OXY)

26
Q

How do the hormones synthesized in magnocellular axons reach the neurohypophysis to be released?

A

Axonal transport

27
Q

What are Herring bodies?

A

Dilations of unmyelinated axons near their terminals (terminal end of axons where hormones are temporarily stored)

Contain vesicles of either AVP or Oxytocin plus a binding protein, neurophysin

28
Q

What is the significance of the median eminence (ME)?

A

the interface for all hypophysiotrophic hormones

29
Q

Discuss some anatomical features of the median eminence

A

Lies outside the BBB (signals don’t have to cross BBB to reach the ME) and forms the floor of the third ventricle

30
Q

What are the 5 major cell types in the anterior pituitary?

A

Acidophils (40%): somatotrophs and lactotrophes
Basophils (10%): corticotrophs, gonadotrophs, thyrotrophs
Chromophobes (50%)

31
Q

What do somatotrophs secrete?

A

Growth hormone (GH)

32
Q

What do lactotrophs secrete?

A

Prolactin (lactation)

33
Q

What do corticotrophs secrete?

A

ACTH (stress)

34
Q

What do gonadotrophs secrete?

A

LH/FSH (reproduction)

35
Q

What do thyrotrophs secrete?

A

TSH

36
Q

What do chromophobes do?

A

paracrine actions

37
Q

Where is ACTH generally secreted?

A

centrally

38
Q

Where is GH/PRL generally secreted?

A

in the periphery

39
Q

Where is TSH generally secreted?

A

Anteriorly

40
Q

Do hormones have a circadian rhythm?

A

Yep!