10/3 Hypothalamus - Pang Flashcards
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
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
preoptic area
- medial preoptic nucleus
- heat dissipation/loss center → vasodilation, sweating
- lateral preoptic nucleus (and MFB)
medial nucleus also has role in releasing GnRH
anterior/supraoptic region
- periventricular nucleus
-
paraventricular nucleus
- see 5
- anterior nucleus
- suprachiasmatic nucleus
- connection to retina → role in circadian rhythm, sleep
-
supraoptic nucleus
-
supraoptic & paraventricular nuclei are interconnected by fx:
- production of ADH/vasopression and oxytocin
- project to post pituitary to regulate water balance
-
supraoptic & paraventricular nuclei are interconnected by fx:
rest, rhythms, ruminate, reproduce
also see lateral hypothalmic area w/ MFB running through this area
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
middle (tuberal) region
- arctuate nucleus
- release tropic factors influencing anterior pituitary hormone release via portal circ
- also: growth hormone RH, dopamine
- dorsomedial nucleus
- CRH, TRH via parvocellular neurosecretion
- ventromedial nucleus
- lateral hypothalmic nucleus (with MFB)
neuroendocrine fx of hypothalamus
- medial preoptic n - preoptic → GnRH
- supraoptic/paraventricular nn - anterior/supraoptic → AVP/oxytocin
- dorsomedial n - middle/tuberal → CRH, TRH (parvocellular type)
- adrenal and thyroid hormone deficiencies
- arcuate n - middle/tuberal → GHRH, DA
- growth hormone def
- galactorrhea (DA neurons)
damage to ventromedial hypothalamic n
damage to dorsomedial hypothalamic n
VMH lesion → obesity/hyperphagia
DMH lesion → passivity
- hypothal rage when stimulated
posterior/mammillary region
- posterior nucleus
- heat generation (vs dissipation by preoptic region nucleus)
- mammillary bodies
- two major inputs: thalamus and hippocampus (via fornix) → learning/memory/emotion
- lateral hypothalmic nucleus (w/ MFB)
damage to posterior hypothalamus → effects
- heat generation/SNS-like fx → periodic hypothermia syndrome
* hypothermia, sweating, vasocil, bradycardia - Papez circuit/mammillary bodies as part of medial limbic circuit : linking emotion/memory/feelings/autonomics → short term memory defect
summary of hypothal nuclei
major hypothalmic fibers
- mammillary body → hippocampal formation : fornix
- mammillary body → thalamus : mammillothalamic tract
- anterior hypothalamus → amygdala : stria terminalis
brainstem → forebrain structures : Medial Forebrain Bundle (MFB)
- runs through lateral hypothalmic nucleus area & lateral preoptic nucleus
functions of hypothalamus
-
satiety
- lateral → hunger
- ventromedial → satiety
-
temperature
- anterior hyp → cooling/PNS
- posterior hyp → heating/SNS
- fertility (neuroendo fx)
- survival : food intake, reproduction, fight/flight
explain role of hypothalamus in food intake/metabolic control
explain role of hypothalamus in temp homeostasis
preoptic: heat dissipation role
posterior: heat generation role
also affects pituitary! → slows down metabolism by lowering TSH
explain role of hypothalamus in circadian rhythm and sleep/wake cycles
look at figure for roles of:
- suprachiasmatic n
- anterior hypothalamus
- posterior nucleus
pituitary hormones and actions
hypothalamus : ANTERIOR PITUITARY relationship
what happens with damage?
damage → hypoadrenalism, hypothyroidism, abnormality in reproductive system
hypothalamus : POSTERIOR PITUITARY relationship
damage?
paraventricular and supraoptic nuclei → ADH/vasopressin & oxytocin
damage → diabetes insipidus (polyuria, polydipsia)
neurotransmitters in hypothalamus
GABA
glutamate
NPY
POMC
orexin/hypocretin
summary of hypothalamus fx
causes of hypothalamis disease
aneurysms
pituitary tumors
head trauma
hypothalamic syndrome
might include
- diabetes insipidus
- endocrine imbalances
- impairment of temp reg
- abnormalities in sleep pattern
- behavioral changes
summary of key info
