Hypothalamus Flashcards

1
Q

Main function of the hypothalamus

A

Maintain homeostasis

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2
Q

What three systems is the hypothalamus functionally related to?

A

Autonomic nervous system
Endocrine system
Limbic system

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3
Q

What are the three zones that the hypothalamus is divided into?

A

Periventricular
Medial
Lateral

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4
Q

What anatomical structures separate the medial and lateral zones?

A

Fornix (ventrally) and mammillothalmic tract (dorsally)

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5
Q

Major nuclei of Lateral zone

A

Lateral preoptic nucleus
Lateral Hypothalamic area
Tuberomammillary (lateral tuberal) nucleus

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6
Q

Function of Lateral hypothalamic area

A

Induces eating when stimulated
Ablation causes anorexia and starvation
Contains important peptide ntms that increase food intake

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7
Q

Function of Tuberomammillary Nucleus

A

Contains large neurons that release histamine as a ntm via axonal projections to widespread portions of the forebrain
Thought to plan an important role in attention and arousal processes
Actively inhibited during sleep

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8
Q

Major nuclei of the Medial zone

A

Preoptic Region: Medial preoptic nucleus
Anterior Region: Suprachiasmatic nucleus, Anterior hypothalamic nucleus, Paraventricular nucleus, Supraoptic nucleus
Middle Region: Dorsomedial nucleus, Ventromedial nucleus, Arcuate nucleus
Posterior Region: Posterior nucleus, Mammillary nucleus

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9
Q

Function of the Medial Preoptic Nucleus

A

Houses neurons that regular gonadotropin secretion from the adenohypothysis
Contains the interstitial nuclei of the anterior hypothalamus, only of which is sexually dimorphic and developmentally regulated by testosterone

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10
Q

Function of Suprachiasmatic Nucleus

A

Immediately dorsal to optic chasm, receives direct input from retina
Plays critical role in control of circadian rhythm

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11
Q

Function of Anterior Hypothalamic Nucleus

A

Between suprachiasmatic and paraventricular nuclei
Involved in temp regulation, contains neuron that sense warmth and initiate response to dissipate excess heat
Bilateral lesions result in hyperthermia

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12
Q

Function of paraventricular nucleus

A

Contains neurons that synthesize and release arginine vasopression, oxytocin, and CRH
Additional neurons project to interomediolateral cell column of the spinal cord (T1-L2) exciting sympathetic preganglionic neurons, as well as projections to brainstem

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13
Q

Function of Supraoptic nucleus

A

Contains neuron that synthesize AVP and oxytocin

Project to neurohypophysis where they release these hormones into circulation

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14
Q

Function of dorsomedial nucleus

A

involved in BP regulation, aggression and savage behavior result

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15
Q

Function of ventromedial nucleus

A

Inhibits the urge to eat when stimulated
Bilateral destruction results in hyperphagia
Neurons play an important role in relaying ingestion-related signals to the brainstem

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16
Q

Function of Arcuate Nucleus

A

Controls the release of various adenohypophyseal hormones

Produce hypothalamic-releasing factors and play prominent role in feeding behavior

17
Q

Function of Posterior Nucleus

A

Involved in thermoregulation
Sense cold and initiate heat conservation and heat production responses
Bilateral lesions result in an inability to thermoregulate (poikilothermia)

18
Q

Function of the Mammillary Nucleus

A

Series of nuclei within the mammillary bodies (part of limbic system)
Receive major input from hippocampus via the fornix
Project to the anterior nucleus of the thalamus via the mammillothalmic tract
Damage to the regions is associated with memory disturbances due to extensive interconnectivity with the hippocampus

19
Q

Mammillary bodies of the hypothalamus receive large axonal projection from the hippocampus via this pathway

A

Fornix

20
Q

Projects from the mammillary bodies to the anterior nucleus of the thalamus

A

Mammillothalamic tract

21
Q

Prominent pathway interconnecting the amygdaloid complex with the medial zone of the hypothalamus

A

Stria terminalis

22
Q

Most complex fiber pathway in the CNS
Contains at least 50 distinct constituent parts of pathways
Extends through the entire lateral hypothalamic zone, interconnecting regions from the septal nuclei to the brainstem

A

Medial forebrain bundle

23
Q

Conducts fibers from the supraoptic and paraventricular nuclei to the neurohypophysis
Magnocellular neurons that synthesize either AVP or oxytocin

A

Supraopticohypophyseal tract

24
Q

Conducts fibers from the arcuate nucleus to the hypophyseal portal system at the median eminence of the infundibulum
Carry neuropeptide release or inhibiting factors which act upon anterior pituitary cells

A

Tuberoinfundibular tract

25
Q

Contains descending axons that regulate spinal cord preganglionic neurons of both sympathetic and parasympathetic division of the ANS

A

Hypothalamospinal tract

26
Q

Major Regulatory functions of the hypothalamus

A
Body temp
Feeding and energy metabolism
Emergency responses to stress
BP and electrolyte composition
Reproductive functions
27
Q

Bilateral destruction of anterior hypothalamus leads to…

A

hyperthermia

28
Q

Bilateral destruction of posterior hypothalamus leads to…

A

inability to thermoregulate

29
Q

Function of AgRP and NPY

A

increase feeding and decrease metabolism

30
Q

Function of POMC and CART

A

decrease feeding and increase metabolism

31
Q

Function of grehlin

A

Released from stomach prior to meal, stimulates feeding

32
Q

Function of polypeptide Y (PPY)

A

Released from GI tract after a meal, inhibits feeding

33
Q

Function of CCK

A

Released from GI tract, produces satiety at brainstem level

34
Q

Function of Leptin

A

Released from fat cells, decreases feeding

35
Q

Function of Orexin and melanin-concentrating hormone

A

produced by neurons in the lateral hypothalamic area, induces feeding

36
Q

What is a craniopharyngioma?

A

congenital tumor originating from Rathke’s pouch, common in children, bitemporal hemianopia

37
Q

What causes hypothalamic memory disturbances?

A

Posterior hypothalamic lesions involving mammillary bodies

38
Q

What is Klein-Levin syndrome?

A

Hypothalamic disorder, common in adolescent males, leads to bulimia, hypersomnolence, hypersexuality