10/3 Hypothalamus - Pang

Question 1

boundaries of hypothalamus

Answer 1

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

Question 2

regions/divisions of hypothalamus

how many nuclei per division?

names of nuclei?

Answer 2

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

Question 3

preoptic area

Answer 3

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

medial nucleus also has role in releasing GnRH

Question 4

anterior/supraoptic region

Answer 4

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

Question 5

functions of ‘anterior’ hypothalamus and results of lesions

Answer 5

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

Question 6

middle (tuberal) region

Answer 6

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)

Question 7

neuroendocrine fx of hypothalamus

Answer 7

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)

Question 8

damage to ventromedial hypothalamic n

damage to dorsomedial hypothalamic n

Answer 8

VMH lesion → obesity/hyperphagia

DMH lesion → passivity

• hypothal rage when stimulated

Question 9

posterior/mammillary region

Answer 9

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)

Question 10

damage to posterior hypothalamus → effects

Answer 10

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

Question 11

summary of hypothal nuclei

Answer 11

Question 12

major hypothalmic fibers

Answer 12

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

Question 13

functions of hypothalamus

Answer 13

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

Question 14

explain role of hypothalamus in food intake/metabolic control

Answer 14

Question 15

explain role of hypothalamus in temp homeostasis

Answer 15

preoptic: heat dissipation role
posterior: heat generation role

also affects pituitary! → slows down metabolism by lowering TSH

Question 16

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

Answer 16

look at figure for roles of:

1. suprachiasmatic n
2. anterior hypothalamus
3. posterior nucleus

Question 17

pituitary hormones and actions

Answer 17

Question 18

hypothalamus : ANTERIOR PITUITARY relationship

what happens with damage?

Answer 18

damage → hypoadrenalism, hypothyroidism, abnormality in reproductive system

Question 19

hypothalamus : POSTERIOR PITUITARY relationship

damage?

Answer 19

paraventricular and supraoptic nuclei → ADH/vasopressin & oxytocin

damage → diabetes insipidus (polyuria, polydipsia)

Question 20

neurotransmitters in hypothalamus

Answer 20

GABA

glutamate

NPY

POMC

orexin/hypocretin

Question 21

summary of hypothalamus fx

Answer 21

Question 22

causes of hypothalamis disease

Answer 22

aneurysms

pituitary tumors

head trauma

Question 23

hypothalamic syndrome

Answer 23

might include

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

Question 24

summary of key info

Answer 24