Hypothalamus Flashcards
the hypothalamus nucleus is
fully fxnal at birth
hypothalamic fxns
control of appetite
fluid balance
glucose concentration
metabolism
sleeping
body temp regulation
continuation of the species
memory and emotional behavior
maintenance of homeostasis
what does the hypothalamus respond to
neural and non-neural stimulation
how is the hypothalamus divided
sagittal into 3 zones
3 zones of the hypothalamus
periventricular
medial and lateral
perventricular
concerned with neuroendocrine regulation
medial and lateral
concerned w/ affective states
including hunger and thirst
the 3 zones of the hypothalamus could be
further subdivided into subnuclei
how else is the hypothalamus divided
optic chiasm
tuber cinereum
mamillary bodies
into 4 regions in rostrocaudal sequence
4 regions of the hypothalamus
preoptic region
supraoptic region (chiasmatic or anterior)
tuberal region (infundibular or middle)
mamillary region (posterior)
preoptic region controls
the release of reproductive hormones from the pituitary gland
what does the preoptic region have
sexual dimorphism
sexual dimorphism –> females
anterior pituitary gland releases gonadotropic hormones
control the menstrural cycle
sexual dimorphism –> males
hormone release in continuous
supraoptic region
contains around 6 nuclei
3 most important are
-suprachiasmic nucleus
-anterior hypothalamic nucleus
-paraventricular and supraoptic nuclei
suprachiasmatic nucleus
receives visual info from retina
fxns in control of circadian rhythms
referred to as the “master clock of the body”
anterior hypothalamic nucleus
involved in temp regulation
paraventricular and supraoptic nuclei
most abundant blood supply in the brain
neurons synthesize the neurohypophyseal hormones –> oxytocin and ADH
tuberal region contains
nuclei involved in the control of anterior pituitary gland hormone release, caloric intake, appetite
tuberal region –> arcuate nucleus
infundibular nucleus
neurons that produce hypothalamic-releasing hormones
axons from tuberal region
form the tuberohypophyseal tract
tuberohypophyseal tract
goes to infundibulum
pass into the hypophyseal portal system
mamillary region
mamillary nuclei
3-4 of them form a mamillary body
what are the mamillary nuclei
major target protection area from hippocampus via the fornix
relaying input related to emotions
what do the mamillary nuclei do
relay input to the anterior nuclei of thalamus
via prominent mammillothalamic tract
mamillary region –> posterior hypothalamic nucleus
contains cells that are sensitive to a decrease in the temp of the blood
what does the posterior hypothalamic nucleus serve as
a thermostat
regulates body temp by conserving and stimulating heat production
what does the hypothalamus receive info from
external and internal conditions
info the hypothalamus receives
specific sensory info
input from visceral senses
contains many neurons that are sensitive to local temp, osmolarity, glucose, sodium
circulating hormones influence it via the circumventricular organs
input from visceral senses
NTS
–> nucleus of the solitary tract-taste
circulating hormones influence it via the circumventricular organs
brain regions near ventricles that lack a BBB
main output from hypothalamus
projections terminate in the sources of hypothalamic input
in addition to the neural input, projects to anterior and posterior pituitary glands
what is the heat loss center
anterior hypothalamus
anterior hypothalamic nuclei
stimulated by warmth and initiates heat loss mechanisms
what do anterior hypothalamic nuclei cause
cutaneous vasodilation and sweating
lesions to anterior hypothalamus
cause hyperthermic
rectal temps sometimes reaching 43 Celsius
main NT of anterior hypothalamus
norepinephrine
what is the heat gain center
posterior hypothalamus
posterior hypothalamic nucleus (heat gain center)
stimulated by cold and initates heat gain mechanisms
causes shivering
lesions to posterior hypothalamus
failure of body temp
main NT of posterior hypothalamus
serotonin
regulation of food intake
through operation of 2 centers
feeding center
satiety
feeding center
located in the lateral nucelli
stimulation evokes eating behavior in conscious animals
destruction causes anorexia
satiety center
located in ventromedial nucleus
stimulation causes cessation of eating
lesions to satiety center
hyperphagia and hypothalamic obesity
what does the satiety center do to the feeding center
inhibits it
what causes an increase in orexin synthesis
fasting
administration of exogenous orexin
induces eating
when does orexin production decrease
at night
causes an individual to fall asleep
the hypothalamus is
master controlled of autonomic fxns
stimulation of anterior and middle hypothalamus
controls the activities of the PS NS
stimulation of the posterior and lateral hypothalamus
controls the activities of the sympathetic NS
rage center
lateral nuclei of the hypothalamus
placidity center
ventromedial nucleus of the hypothalamus
rage center is stimulated by
amygdaloid nucleus int he limbic system
rage center is inhibited by
signals from the placidity center and the neocortex
where is the hypothalmus
on the floor of the brain
along the walls of the 3rd ventricle
behind the optic chiasm
above the pituitary
how does the hypothalamus control the pituitary
2 ways
