10/3 Hypothalamus - Pang Flashcards Preview

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Flashcards in 10/3 Hypothalamus - Pang Deck (24):
1

boundaries of hypothalamus

anterior: ant end of optic chiasm

posterior: post end of mammillary bodies

 

*between the optic chiasm and mammilary bodies, tuber cinereum is connected to pituitary stalk

2

regions/divisions of hypothalamus

 

how many nuclei per division?

names of nuclei?

anterior to posterior:

 

1. preoptic area (2)

  • medial preoptic n
  • lateral preoptic n

2. anterior (supraoptic) region (5)

  • paraventricular n
  • medial preoptic n
  • lateral preoptic n
  • suprachiasmatic n
  • supraoptic n

3. middle (tuberal) region (4)

  • dorsomedial hypothalmic n
  • ventromedial hypothalmic n
  • lateral hypothalmic area (incl MFB - medial forebrain bundle)
  • arcuate n

4. posterior (mammillary) region (3)

  • posterior n
  • mammillary body
  • lateral hypothalamic nucleus (and MFB)

 

2 : 5 : 4 : 3 nuclei per region

3

preoptic area

  1. medial preoptic nucleus
    • heat dissipation/loss center → vasodilation, sweating
  2. lateral preoptic nucleus (and MFB)

 

medial nucleus also has role in releasing GnRH

4

anterior/supraoptic region

  1. periventricular nucleus
  2. paraventricular nucleus
    • ​​see 5
  3. anterior nucleus
  4. suprachiasmatic nucleus
    • ​​connection to retina → role in circadian rhythm, sleep
  5. supraoptic nucleus
    • supraoptic & paraventricular nuclei are interconnected by fx:
      • production of ADH/vasopression and oxytocin
      • project to post pituitary to regulate water balance

 

rest, rhythms, ruminate, reproduce

 

also see lateral hypothalmic area w/ MFB running through this area

5

functions of 'anterior' hypothalamus and results of lesions

rest, rhythms, ruminate, reproduce

fx → lesion result

  • circadian rhythms and sleep (suprachiasmatic nucleus)→ loss of diurnal rhythm, insomnia
  • water retention (paraventricular/supraoptic nn) → polydipsia, hypodipsia
  • heat dissippation/SNS like fx (preoptic n) → vasoconstriction, hyperthermia, tachycardia
  • GnRH releasing neurons (preoptic area) → infertility
  • LHA → hyper/hypophagia

6

middle (tuberal) region

  1. arctuate nucleus
    • release tropic factors influencing anterior pituitary hormone release via portal circ
    • also: growth hormone RH, dopamine
  2. dorsomedial nucleus
    • ​​CRH, TRH via parvocellular neurosecretion
  3. ventromedial nucleus​​
  4. lateral hypothalmic nucleus (with MFB)

7

neuroendocrine fx of hypothalamus

  1. medial preoptic n - preoptic → GnRH
  2. supraoptic/paraventricular nn - anterior/supraoptic → AVP/oxytocin
  3. dorsomedial n - middle/tuberal → CRH, TRH (parvocellular type)
    • adrenal and thyroid hormone deficiencies
  4. arcuate n - middle/tuberal → GHRH, DA
    • growth hormone def
    • galactorrhea (DA neurons)

8

damage to ventromedial hypothalamic n

damage to dorsomedial hypothalamic n

VMH lesion → obesity/hyperphagia

DMH lesion → passivity

  • hypothal rage when stimulated

9

posterior/mammillary region

  1. posterior nucleus
    • heat generation (vs dissipation by preoptic region nucleus)
  2. mammillary bodies
    • two major inputs: thalamus and hippocampus (via fornix) → learning/memory/emotion
  3. lateral hypothalmic nucleus (w/ MFB)

10

damage to posterior hypothalamus → effects

1. heat generation/SNS-like fx → periodic hypothermia syndrome

  • hypothermia, sweating, vasocil, bradycardia

 

2. Papez circuit/mammillary bodies as part of medial limbic circuit : linking emotion/memory/feelings/autonomics → short term memory defect

11

summary of hypothal nuclei

12

major hypothalmic fibers

1. mammillary body → hippocampal formation : fornix

2. mammillary body → thalamus : mammillothalamic tract

3. anterior hypothalamus → amygdala : stria terminalis

 

brainstem → forebrain structures : Medial Forebrain Bundle (MFB) 

  • runs through lateral hypothalmic nucleus area & lateral preoptic nucleus

13

functions of hypothalamus

  1. satiety
    • lateral → hunger
    • ventromedial → satiety
  2. temperature
    • anterior hyp → cooling/PNS
    • posterior hyp → heating/SNS
  3. fertility (neuroendo fx)
  4. survival : food intake, reproduction, fight/flight 

14

explain role of hypothalamus in food intake/metabolic control

15

explain role of hypothalamus in temp homeostasis

preoptic: heat dissipation role

posterior: heat generation role

 

also affects pituitary! → slows down metabolism by lowering TSH

16

explain role of hypothalamus in circadian rhythm and sleep/wake cycles

look at figure for roles of:

1. suprachiasmatic n

2. anterior hypothalamus

3. posterior nucleus

17

pituitary hormones and actions

18

hypothalamus : ANTERIOR PITUITARY relationship

 

what happens with damage?

damage  → hypoadrenalism, hypothyroidism, abnormality in reproductive system

19

hypothalamus : POSTERIOR PITUITARY relationship

 

damage?

paraventricular and supraoptic nuclei → ADH/vasopressin & oxytocin

 

damage → diabetes insipidus (polyuria, polydipsia)

20

neurotransmitters in hypothalamus

GABA

glutamate

NPY

POMC

orexin/hypocretin

21

summary of hypothalamus fx

22

causes of hypothalamis disease

aneurysms

pituitary tumors 

head trauma

23

hypothalamic syndrome

might include

  • diabetes insipidus
  • endocrine imbalances
  • impairment of temp reg
  • abnormalities in sleep pattern
  • behavioral changes

24

summary of key info

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