44 - Hypothalamus Flashcards by Mikey Montalbano

Hypothalamus - Blood Supply

PCA

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Hypothalamus - Periventricular Zone

Parvocellular cells projecting to Anterior Pituitary via median eminence, influencing secretion

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Hypothalamus - Medial Zone

Diffuse ass nuclei:

Preoptic Nucleus
Paraventricular Nucleus
Dorsomedial Nucleus
Ventromedial Nucleus
Arcuate Nucleus
Supraoptic Nucleus
SupraChiasmatic Nucleus
Mammilary Body

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Preoptic Nucleus

Just inferior to anterior commisure, superior to Optic Chiasm

Magnocellular neurons project to posterior pituitary

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Dorsomedial Nucleus

Ventromedial Nucleus

Magnocellular, oxy & vas to PP

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SupraChiasmatic Nucleus

Circadian Rhythms

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Location of Medial Forebrain Bundle

Lateral Hypothalamus

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Magnocellular nuclei in Hypothalamus

Paraventricular Nucleus
Supraoptic Nucleus

Project axons to posterior pituitary
Release Oxytocin & Vasopressin

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Parvocellular Cells in Hypothalamus

Everywhere!

Project to median eminence, release in anterior pituitary, trigger release of hormones!

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Inputs to the hypothalamus

Cingulate Gyrus
Orbital cortex
Ventral striatum
Septal Nuclei
Hippocampus
Amygdala

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Outputs from the hypothalamus

Widespread cortical areas
Septal nuclei
Anterior nucleus
Mammilothalamic tract
Amygdala

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Hypothalamic Pathways

DLF
MFB
ST &amp; VAP
Fornix, Mammilothalamic and Mammilotegmental Tracts
Optic Nerve

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Descending Hypothalamus regulates the ANS

Info comes in
HypoThalamus projects down via VLF & MFB
Regulating Dorsal Motor Nucleus of X and Solitary Nucleus
Areas around Nucleus Ambiguus affect heart function.
Additionally, large projection down to spinal cord from HT to regulate PS and S preganglionics through spinal cord to regulate postganglionics

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Hypothalamic Regulation of PNS

Mediated through dorsal motor nucleus of X.

Regions in reticular formation near nucleus ambiguus project to gut and heart.

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Motor Nucleus of X - Inputs

VLF and MFB

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Hypothalamus Four Fs

Fighting
Fleeing
Feeding
FUCKINGGGGGG

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6 physiologic needs controlled by Hypothalamus

BP & Electrolytes
Temperature (ANS & motivated behavior, metabolic pathways)
Energy metabolism (eating, behavior, metabolic rate)
Reproduction (hormonal control of mating, pregnancy and lactation)
Responses to stress (directing blood flow nad stimulating adrenal se(x)cretions)
Adaptive emotional responses

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Hypothalamus - Location

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Lining the walls of the 3rd ventricle, above the pituitary

Not too far from VTA

Fornix

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Divides Hypothalamus into medial and lateral regions

Anterior border of the hypothalamus

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Line between Anterior Commisure and Mammilary Bodies

Paraventricular Nucleus

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Microcosm of HT function
Both endocrine and neural regulation

Parvocellular:
Medial - secrete CRH
Dorsal/Ventral - neurons project to medulla & spinal cord to exert autonomic control. Se(x)crete oxytocin and vasopressin (neuromodulators)

Magnocellular:
Two distinct populations control endocrine function, se(x)creting right into the posterior pituitary

Visceral afferents

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CN VII IX X contain visceral info
They project to the nucleus of the solitary tract.
Relayed to parabrachial nucleus
Projects to hypothalamus and other limbic structures.

Indirect control of autonomic responses

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Comes from cortex, amygdala, periaqueductal grey

Hypothalamus - Neural Input, Neural Output

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Controls ANS (emotion)

Hypothalamus - Neural Input, Hormonal Output

Oxytocin release for galactorrhea

Hypothalamus - Hormonal Input, Neural Output

Drives and motivated behavior (SEXXXXXX)

Hypothalamus - Hormonal Input, Hormonal Output

Vasopressin release for anti-diuresis

Servo-Control Systems

Thermostat Receives sensory info and feedback signals Compares with biological set points Adjusts ANS, endocrine and behavioral responses aimed at maintaining homeostasis

Temperature Regulation

Systemic pyrogens such as IL-1 can cross BBB and increase biological set point, causing fever. HT contains feedback detectors. Peripheral receptors transmit info through temperature pathways to CNS. Central receptors in anterior hypothalamus that modulate their activity related to blood temperature. Combination of peripheral and central receptors

Lesion Anterior hypothalamus

Chronic hyperthermia Anterior HT decreases internal temperature

Stimulate Anterior Hypothalamus

Dilate blood vessels, suppress shivering. Anterior HT decreases internal temperature

Lesion Posterior hypothalamus

Hypothermia if placed in cold environment Posterior HT increases internal temp

Stimulate Posterior Hypothalamus

Shiver & constrict blood flow Posterior HT increases internal temp

Long term exposure to cold

Increased HT secretion of TRH, resulting in increased TSH and T4, increasing body heat by increasing tissue metabolism

Animals adjust their food intake to achieve normal body weight

Cool

Hypothalamic contribution to food intake

Feeding center | Satiety center.

Lesions of Ventromedial hypothalamus

Hyperphagia & obesity Ventromedial must control satiety

Lesions of Lateral hypothalamus

Aphagia & starvation Lateral must control food intake

Caloric homeostasis

Arcuate Nucleus Paraventricular Nucleus Lateral Hypothalamic Area Insulin & Leptin hit the ARC In response to these particular signals, ARC INHIBITS NPY/AgRP because they are anabolic, stimulating LHA and inhibiting PVN Meanwhile, ARC EXCITES Alpha-MSH/CART, stimulating PVN & inhibiting LHA PVN releases CRH & Oxytocin LHA releases MCH & Orexins

PVN

Catabolic

LHA

Anabolic

Adiposity Signals Pathways

Leptin and Insulin circulate in concentrations proportional to body fot content and energy balance Act on central effector pathways in the hypothalamus Activating catabolic pathways, inhibiting anabolic pathways

Chronic Leptin Deficiency

Less PVH innervation from ARC Can be rescued by leptin treatment DURING DEVELOPMENT

44 - Hypothalamus Flashcards

(43 cards)