Hypothalamus Flashcards
what is the anterior boundary of the hypothalamus?
optic chiasm and lamina terminalis
what is the lateral boundary of the hypothalamus?
optic tract and internal capsule
what is the posterior boundary of the hypothalamus?
cerebral peduncles
what is the superior boundary of the hypothalamus?
hypothalamic sulcus and thalamus
what are the hypothalamic regions?
pre optic, anterior, middle, posterior
pre optic region
rostral to optic chiasm
anterior region
dorsal to optic chiasm
middle region
optic chiasm to mammillary bodies
posterior region
mammillary bodies and caudal
what are the hypothalamic zones
periventricular, medial/intermediate, lateral
what does the periventricular zone do
endocrine control of anterior pituitary
what does the medial zone do
regulation of posterior pituitary, regulation of autonomic nervous system
what does the lateral zone do
limbic system integration
what is the medial forebrain bundle
axons from the hypothalamus that project back to the brainstem
hypothalamic nuclei of the pre optic region
medial and lateral pre optic nucleus
hypothalamic nuclei of the anterior region
paraventricular, anterior, lateral hypothalamic, periventricular, supraoptic, suprachiasmatic
hypothalamic nuclei of the middle region
dorsomedial, lateral hypothalamic, ventromedial, periventricular, arcuate
hypothalamic nuclei of the posterior region
posterior, lateral hypothalamic, mammillary body
hypothalamic nuclei of the periventricular zone
periventricular, arcuate, medial pre optic, paraventricular
periventricular nucleus hormones
gonadotropin releasing hormone, dopamine (inhibits prolactin), somatostatin (inhibits growth hormone)
arcuate nucleus hormones
gonadotropin releasing hormone, somatostatin, growth hormone releasing hormone
medial preoptic nucleus hormones
gonadotropin releasing hormone
paraventricular nucleus hormone (anterior pituitary)
thyrotropin releasing hormone, corticotropin releasing hormone
how is the anterior pituitary regulated
hypothalamus releases chemicals into the hypophysial portal system which are then transmitted to the anterior pituitary
hypothalamic nuclei that act on the posterior pituitary
supraoptic and paraventricular
supraoptic nucleus hormones
primarily secretes vasopressin with minimal oxytocin
paraventricular nucleus hormones
primarily secretes oxytocin with minimal vasopressin
posterior pituitary regulation
magnocellular neurosecretory system
releases vasopressin and oxytocin directly into systemic circulation
vasopressin
promotes water absorption and elevates BP
oxytocin
stimulates uterine contractions and ejection of milk from mammary glands
also important for forming bonds
where does autonomic regulation from the medial zone originate
paraventricular, dorsomedial, posterior and lateral hypothalamic nuclei
autonomic regulation pathway from hypothalamus
through medial forebrain bundle and then dorsolateral tegmentum, synapse on several cranial nerve autonomics
hypothalamospinal tract (parasympathetics and sympathetics)
hypothalamospinal tract
projections from nuclei in hypothalamus through dorsolateral tegmentum
synapse on nucleus of IMLCC
what is Horner’s syndrome
autonomic disfunction (sympathetics)
ptosis, miosis, anhidrosis
peripheral Horner’s will often be just ptosis and miosis
what are the autonomic coordinating nuclei? what do they do?
solitary, parabrachial, and dorsal raphe nuclei, ventrolateral medulla, pontomedullary reticular formation
work in conjunction with the hypothalamus
solitary nucleus
viscerosensory information to intermediolateral nuclei, thalamus, and hypothalamus
parabrachial nucleus
viscerosensory info to the forebrain and paraventricular nucleus
dorsal raphe nucleus
serotonin release to regulate pain reactions
ventrolateral medulla
regulation of blood pressure
pontomedullary reticular formation
startle response - tense up to protect self
what nuclei are involved in sleep/wake regulation?
ventral lateral preoptic
mammillary
suprachiasmatic
what nuclei are involved in thermoregulation
anterior - heat dissipation
posterior - conserve heat
what nuclei are involved in appetite
ventromedial - decreases
lateral - increases
what nuclei are involved in thirst
anterior
what hypothalamic nuclei are involved in the limbic system
lateral hypothalamus, ventromedial and mammillary nuclei
what regulates our circadian rhythm
daylight signals from retina through retinohypothalamic tract
at night this pathway signals pineal gland to release melatonin
retinohypothalamic tract
melanopsin-containing ganglion neurons to suprachiasmatic nucleus
to paraventricular nucleus
to IMLCC
to stellate ganglion to pineal gland
OR to adrenal medulla
what is the key nucleus that starts our sleep cycle
ventral lateral preoptic
what happens during the sleep cycle
GABAergic projections inhibit neurons that maintain arousal and the tuberomammillary nucleus that activates major areas of the forebrain
dreaming cycle
preoptic sleep center turns on REM, lateral hypothalamus inhibits REM through orexin
decreased orexin receptors is linked to narcolepsy
what areas control urination
medial preoptic and lateral hypothalamic
time to go pathway
