HYPOTHALAMUS Flashcards
What are 2 embryological pouches of Pituitary Glands?
Anterior pituitary (adenohypophysis)
Posterior pituitary (neurohypophysis)
Contains axons and terminals of neurons whose cell bodies are located in the hypothalamus
Secrete oxytocin and vasopressin
Posterior pituitary (neurohypophysis)
Contain glandular cells that secrete hormones into circulation
Release is controlled by hypothalamus
Anterior pituitary (adenohypophysis)
from an evagination of the floor of the developing ventricular system
Posterior pituitary (neurohypophysis)
ectoderm cells on the roof of the developing pharynx that invaginate, forming Rathke’s pouch
Anterior pituitary (adenohypophysis)
Part of diencephalon
Extends from region of optic chiasm to caudal border of mammillary bodies
HYPOTHALAMUS
Hypothalamus is ventrally separated from thalamus by a shallow groove on the wall of the 3rd ventricle
hypothalamic sulcus
arises from tuber cinereum and continues inferiorly as pituitary stalk
Infundibulum
region / bulge of tuber cinereum where hypothalamic neurons release regulating factors that are carried by portal vessels to the anterior pituitary
Median eminence
hypothalamus is posterior to ______
optic chiasm
“gray protuberance”; bulge between the optic chiasm and mammillary bodies
Tuber cinereum
what structure lies within the pituitary fossa
Pituitary Gland
saddle shaped depression on the sphenoid bone that houses the pituitary gland;
where pituitary gland lies
Sella turcica
beneath the floor of the sella turcica
Sphenoid sinus
extension of dura covering the superior portion of the pituitary fossa; through which the pituitary stalk traverses
Diaphragma sella
Has opening where pituitary stalk passes throug
Diaphragma sella
from optic chiasm to lamina terminalis and anterior commissure
Preoptic area
bound laterally by cavernous sinus
Left and right would be cavernous sinus
Pituitary fossa
Lie just behind and inferior to the optic chiasm
Pituitary fossa
Caudally merges with midbrain tegmentum
HYPOTHALAMUS
HEAL function of hypothalamus
Homeostasis (hunger, thirst, sexual desire, sleep-wake cycle, etc)
Endocrine control via pituitary gland
Autonomic control
Limbic mechanisms
Divided into 3 areas from medial to lateral / coronal section:
Periventricuar
Medial
Lateral
structure that lie closest to the 3rd ventricle
Periventricular nucleus
Fibers of the fornix pass through the hypothalamus on the way to the mammillary body, dividing it to:
Medial hypothalamic area
Lateral hypothalamic area
Note: Medial and lateral zone are divided by fornix (pass through from hippocampus towards mamillary body, towards hypothalamus)
Lateral hypothalamic area has 2 bundles:
Lateral hypothalamic nucleus and other smaller nuclei
Medial forebrain bundle
(Bundle of lateral hypothalamic area)
run through the lateral hypothalamic area in the rostrocaudal direction, carry connections to and from the hypothalamus
Medial forebrain bundle
Medial Hypothalamic Area is divided into four regions from anterior to posterior
Preoptic
Anterior (Supraoptic) region
Middle (Tuberal) Hypothalamic Region
Posterior (Mammillary) Hypothalamic Region
Medial Hypothalamic Area region:
contain oxytocin or vasopressin and project to the posterior pituitary
Supraoptic and paraventricular nuclei
Medial Hypothalamic Area region:
lateral and medial preoptic nucleus; rostrally continuations of the lateral and medial hypothalamic areas
Preoptic
Medial Hypothalamic Area region:
“master clock” for circadian rhythms; receive inputs from retinal ganglion cells
Suprachiasmatic nucleus
Paraventricular nucleus (mainly), dorsomedial hypothalamic nucleus and lateral and posterior hypothalamus
HYPOTHALAMIC CONTROL OF ANS
project to median eminence to control pituitary
Arcuate nucleus
Control of autonomic is done mainly by what nucleus
Paraventricular nucleus
MFB (medial forebrain bundle) has fibers sent to dorsolateral brainstem and periaqueductal gray matter
HYPOTHALAMIC CONTROL OF ANS
MFB –> preganglionic PSY nuclei –> intermediate zone of the sacral spinal cord
This responsible for_____
parasympathetic control
HYPOTHALAMIC-LIMBIC PATHWAYS:
Hippocampal formation projects to mammillary body via
fornix
HYPOTHALAMIC-LIMBIC PATHWAYS:
Mammillary body to anterior thalamic nucleus via _________ then project to ________
mammillothalamic tract, cingulate gyrus
HYPOTHALAMIC-LIMBIC PATHWAYS:
Amygdala (reciprocal connections) via:
Stria terminalis
Ventral amygdalofugal pathway
Emotional influence on autonomic pathways, homeostatic pathways including immune system
HYPOTHALAMIC-LIMBIC PATHWAYS
Physical expression of emotion
Increase HR and BP, dryness of mouth, flushing or pallor, sweating
increase in ^ when we express emotion
HYPOTHALAMIC-LIMBIC PATHWAYS
HYPOTHALAMIC-LIMBIC PATHWAYS:
Lateral hypothalamic nuclei is for _______
RAGE
HYPOTHALAMIC-LIMBIC PATHWAYS:
Ventromedial nucleus is for _____
passivity
Lateral Hypothalamus (hunger center lesion will cause ______
will cause a decrease body weight because of lack of appetite
Medial Hypothalamus (satiety center) lesion will cause specifically ventromedial nucleus _____
cause obesity because of continuous eating since the ventromedial nucleus inhibits appetite
hormone released by adipose tissue
Binds to Ob receptors in hypothalamus
Reduce appetite
Leptin
secreted by gastric mucosal cells
Binds hypothalamus
Stimulates appetite
Ghrelin
activation of osmoreceptors in anterior regions of hypothalamus causes _____
Thirst
(THERMOREGULATION)
What part of hypothalamus:
detect increased body temperature
Activates heat dissipation
Dilation of skin blood vessels and sweating
Anterior hypothalamus
(THERMOREGULATION)
What part of hypothalamus:
conserves heat; heat production
Vasoconstriction in skin and
inhibition of sweating, shivering
Posterior hypothalamus
produced in hypothalamus and released in posterior pituitary
Increase nurturing behaviors
increased in mothers
Oxytocin
Anterior pituitary hormones produces:
Adrenocorticotropic hormone (ACTH)
Growth hormone (GH)
Prolactin (PRL)
Thyroid-stimulating hormone (TSH)
Luteinizing hormone (LH)
Follicle-stimulating hormone (FSH)
What controls the hormone production of the anterior pituitary?
HYPOTHALAMUS
Posterior pituitary hormones release:
Oxytocin
Vasopressin (aka Arginine vasopressin AVP or antidiuretic hormone ADH)
The release of anterior pituitary hormones is controlled by thalamus through _______
hypophysial portal system
HYPOPHYSEAL PORTAL :
SYSTEMPituitary gland receives arterial blood
inferior and superior hypophysial arteries
HYPOPHYSEAL PORTAL SYSTEM:
Neurons lying adjacent to the 3rd ventricle project to the median eminence where they secrete inhibitory and releasing factors through what structures:
Arcuate nucleus
Periventricular nucleus
Medial preoptic nucleus
Medial parvocellular portions of the paraventricular nucleus
HYPOPHYSEAL PORTAL SYSTEM:
Secreted inhibitory and releasing factors are carried by ___________ to anterior pituitary
hypophyseal portal veins
HYPOPHYSEAL PORTAL SYSTEM:
Hormones from pituitary are picked up by secondary _________ and carried by draining veins to the _________
secondary capillary plexus, cavernous sinus
Passed along axons and released at axon terminals
Absorbed in fenestrated capillaries of the posterior lobe of pituitary gland
Oxytocin and Vasopressin
where is Oxytocin and Vasopressin secreted ?
posterior pituitary
Anti-diuretic hormone (ADH)
(prevents urination)
Vasopressin
Produced in / released by supraoptic nucleus
Vasoconstriction and anti-diuretic
Increased absorption of water in distal convoluted tubules and collecting tubules of kidney
Vasopressin
Supraoptic nucleus acts as osmoreceptor means….
High osmotic pressure of blood – increase vasopressin – increase water reabsorption in kidney
Contraction of smooth muscles of the uterus and contraction of myoepithelial cells surrounding the alveoli and ducts of breasts for milk expression
Oxytocin
regulates release of hormones
Hypothalamic-pituitary axis
Synthesize vassopresin
Supraoptic nucleus
Control parasympathetic system
Preoptic and anterior nuclei
Synthesizes oxytocin
Paraventricular nucleus
Regulate temperature (response to heat)
Anterior hypothalamic nucleus
Regulate temperature (response to cold)
Posterior hypothalamic nucleus
Initiate eating and increase food intake (hunger center) and Increase water intake ( thirst center)
Lateral hypothalamic nuclei
Inhibiting intake and decrease food intake
Medial hypothalamic nuclei
Controls circadian rhythm
Suprachiasmatic nucleus
