Ch. 30 - Hypothalamus Flashcards by Chris Rodarte

Boundaries of the HT

Rostral = Lamina terminalis

Superior = hypothalamic sulcus

Lateral = substantia inominata (front) + posterior limb of IC (back)

Medial = Third ventricle

Caudal = Tegmentum and PAG

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Medial Preoptic area contains cells that make ______.

GnRH

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Which HT area is “sexually dimorphic”

Medial Preoptic nucleus

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The lateral zone contains what fibers?

Medial Forebrain Bundle

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Nuclei in the HT lateral zone

Lateral HT nucleus
Tuberal Nuclei

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Stimulation of the Lateral HT nucleus will result in…

Feeding behavior

Lesion causes anorexia

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Tuberal nuclei location and function

Lateral Zone

Sends releasing hormones via tuberoinfundibular tract
Sends histaminergic input to CB

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Regions of the Medial zone

Supraoptic

Tuberal

Mammillary

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Tuberal region is located internal to the _____

Tuber cinereum

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Where in the medial zone is the supraoptic region?

What are the nuclei of the supraoptic region?

In the rostral-most portion of the medial zone

Supraoptic
Paraventricular
Suprachiasmatic
Anterior

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Function of SON and PVN?

contain oxcytocin + ADH

transmit these substances via supraoptico-hypophysial tract for release to the neurohypophysis

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Location / Main function of the Anterior nucleus

Location = In the supraoptic region

Main function = Body temperature maintenence

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Nuclei of the tuberal region

Ventromedial

Dorsomedial

Arcuate

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Ventromedial nucleus function?

Satiety center

If stimulated = no feeding behavior

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Location and function of the Dorsomedial nucleus

Location = tuberal region

Function = regulation of emotional behavior

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Stimulation of dorsomedial nucleus results in…

sham rage

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Arcuate nucleus function

the primary nucleus containing releasing hormones

transmitted via **tuberoinfundibular tract **and Hypophysial portal system

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Mammillary region nuclei

medial

intermediate

lateral

posterior

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Which mammillary nucleus is the target for the fornix? Where are these fibers coming from?

Medial mammillary nucleus

Subiculum of the hippocampus

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Efferent connection of the medial mammillary nucleus?

Mammillothalamic tract

**to the Anterior Nucleus of the Dorsal Thalamus

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Neurons of the periventricular zone (***not par_a_ventricular nucleus) project to the __________ via the __________

anterior pituitary via the tuberoinfundibular tract

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Adopose tissue releases _____, which travels to receptors in the _____ nucleus.

Some of these neurons contain ____ and _____, while others contain ____ and _____

Leptin >> receptors in arcuate nucleus

aMSH + CART
NPY + AgRP

Function of aMSH and CART-containing neurons

project to LATERAL zone, PVN, and lateral horn of Sp. cord

Increases TSH and ACTH = increased metabolism and Sy tone

Decreased feeding behavior

Function of NPY and AgRP

Promotes decrease in TSH and ACTH = decreased metabolism and increased feeding behavior

Major blood supply to HT

perforating arteries of the circle of Willis (branches of...) _A1_ = anteromedial group _P1_ = posteromedial group \*posterior group also gets some from _thalamoperforating_ arteries

Fornix divisions & projections

**Precommisural** (*small*) \>\> Anterior HT region **Postcommissural** (*large) \>\> *Medial Mammillary nucleus

MFB connects the...

septal nuclei HT Midbrain Tegmentum

Two projection systems from Amygdala to HT

* **Stria Terminalis** (*older*, goes to _septal/Preoptic nuclei and Medial zone_) * **Ventral Amygdalofugal pathway** (*new*, passes under lentifurm nucleus and through substantia inominata to go to the _septal/Preoptic nuclei and Lateral zone_)

Mammillary peduncle connections?

originates from midbrain reticular formation terminates in the lateral mammillary nucleus

Where do the **thalamohypothalamic fibers** originate from?

Dorsomedial nucleus

What is the only cortical HT connection

Corticohypothalamic fiber from the **prefrontal** cortex

Two origins for retinohypothalamic fibers?

1. as direct axons from **optic chiasm** 2. **collaterals** of retinogeniculate fibers

Major ascending _efferent_ projection from the HT? (include branches and targets)

_Mammillary fasiculus_ (bifurcates into **Mammillothalamic** and **mammillotegmental** tracts) Mammilothalamic = Anterior thalamic nucleus Mammillotegmental = tegmental nuclei of the midbrain RF

What are the other efferent HT ascending projections?

**Hypothalamo-thalamic** fibers (to DM nucleus) **Hypothalamo-amygdaloid** fibers (via ST and VAFP)

4 main descending HT projections

HT-spinal HT-medullary Dorsal Longitudinal Fasiculus Mammillotegmental Tract

Hypothalamomedullary origin/target HT-spinal origin/target

Both from **PVN** nucleus _HM_ = goes to **solitary**, **dorsal vagal**, and **ambiguus** _HS_ = terminates on **IML** neurons

DLF origin

medial HT zone

mammillotegmental tract origin

Medial Mammillary nucleus

DLF and mammillotegmental tract terminate at the \_\_\_\_\_\_\_

PAG

major function of DLF and Mammillotegmental?

indirect influence of autonomic nuclei

OT and ADH are secreted by.... They are stored in...

Magnocellular cells in PVN and SO Stored in **Herring bodies**

Lesion of SO + PVN results in...

Diabetes insipidus

Tuberoinfundibular tract comes from _______ neurons

parvicellular neurons in arcuate nucleus and periventricular zone

axons of the T-I tract convey releasing hormones to the

median eminence

cutoff for classifying micro/macroademonas

1 cm

IGF1 is considered a \_\_\_\_\_\_

somatomedin

FSH secreting tumors only affect

menapausal women -- it may shut down cycle

Prolactin release is inhibited by...

Prolactin-inhibiting factor (PIF)

activation of the Caudolateral HT produces what kind of behavior?

Anxiety-related 1. increased **Sympathetics** 2. increased **aggression** 3. increased **hunger** 4. increased Body **Temperature**

Stimulation of the Rostromedial HT produces what kind of behavior?

Contentment 1. Increased **Parasympathetic** 2. Increased **Passiveness** 3. Increased **Satiety** 4. **_Reduced_ Temperature** 5.

Explain Biofeedback

Some people are able to alter blood pressure/body temperature through neural mechanisms that haven't been elucidated.

In the baroreceptor reflex, the solutary nucleus transmits to the ___________ nuclei

**PVN**, **DM**, and **Lateral** HT nuclei These project back down to the dorsal vagal nuclei in the medulla

In the temperature regulation reflex, an increase in temperature will stimulate the __________ nucleus, responsible for heat dissipation What part is responsible for heat conservation?

_Rostral HT_ dissipates Caudal HT is responsible for: * heat conservation (via vasoconstriction) * heat production (via shivering)

The water balance reflex is said to be \_\_\_\_\_. Basic mechanism

_neurohumoral_ Osm is monitored by Anterior HT (near preoptic and PVN) Output from these receptors influences ADH release