Hypothalamus-Pituitary Relationship Flashcards Preview

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Flashcards in Hypothalamus-Pituitary Relationship Deck (40):
1

What are the nuclei of the hypothalamus?

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

2

What is the median eminence?

The floor of the hypothalamus and the convergence point for axons

3

What are some general hypothalamic functions and the associated nuclei?

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

4

What are some important hypothalamic releasing hormones?

GnRH (inhibited by GnIH)
CRH
TRH
GHRH
Somatostatin
Dopamine

5

What do the hypothalamic releasing factors target?

the anterior pituitary

6

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

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

7

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

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

8

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

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

9

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

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

10

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

peptide (14AA)
periventricular (PeVN)
Somatotrope
cAMP
Inhibits GH

11

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

amine
ARC
Lactotrope - prolactin
Milk production

12

Discuss Kallman's syndrome

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

13

Describe the hypophyseal portal system

vascular connections between the hypothalamus and pituitary gland

14

Describe the connections of the hypophyseal portal system

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

15

What is the importance of hormone pulsatility?

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

16

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

Tuberoinfundibular system

Neurohypophyseal tract

17

Discuss the tuberoinfundibular system

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

Discuss the Neurohypophyseal tract

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

19

What are the different anatomical landmarks of the anterior pituitary?

Pars distalis (90%)
Pars intermedia
Pars tuberalis

20

What are the different anatomical landmarks of the posterior pituitary?

Pars nervosa
Infundibulum (stalk)

21

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

Adenohypophysis

made up of glandular tissue: cords of epithelial cells

22

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

Neurohypophysis

made up of neural tissue: terminal axons and glial cells

23

What is the blood supply of the posterior pituitary?

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

24

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

Magnocellular axons

25

What are the major hormones of the neurohypophysis?

Arginine vasopressin (AVN) and oxytocin (OXY)

26

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

Axonal transport

27

What are Herring bodies?

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

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

the interface for all hypophysiotrophic hormones

29

Discuss some anatomical features of the median eminence

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

30

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

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

31

What do somatotrophs secrete?

Growth hormone (GH)

32

What do lactotrophs secrete?

Prolactin (lactation)

33

What do corticotrophs secrete?

ACTH (stress)

34

What do gonadotrophs secrete?

LH/FSH (reproduction)

35

What do thyrotrophs secrete?

TSH

36

What do chromophobes do?

paracrine actions

37

Where is ACTH generally secreted?

centrally

38

Where is GH/PRL generally secreted?

in the periphery

39

Where is TSH generally secreted?

Anteriorly

40

Do hormones have a circadian rhythm?

Yep!