Hypothalamus (3-26-14) Flashcards
what does the OVLT (organum vasoculosum of the lamina terminalis) do?
trigger febrile responses
osmoreceptors
what does the median eminence do?
release hypothysiotropic hormones into portal system –> adenohypophysis
what does the neurohypophysis do?
it’s where the axons of supraoptic and paraventricular neurons RELEASE ADH/OXYTOCIN
what does the SFO (subfornical organ) do?
osmoreceptors for blood/CSF osmolarity
what does the area posterma do?
chemoreceptors for noxious substances in blood
Emetic center
what does the pineal gland do?
melatonin secretion –> circadian rhythms
what does the medial preoptic nucleus do?
medial preoptic n. is w/i the POAH (pre-optic area of the hypothalamus)
- thermoregulation
- thirst
- sexual dimorphic nucleus = gender selection
- GnRH producing neurons –> olfactory bulb (Kallmann’s)
- site of clomiphene action (increases GnRH secretion for fertility drug)
what does the lateral preoptic nucleus do?
sleep onset (non-REM stages)
anterior hypothalamic lesions cause…
hyperthermia
posterior hypothalamic lesions cause…
hypothermia
explain how a fever happens
macrophages –> endogenous Pyrogens (IL-6, IL-1B, TNF, IFNs) –> leak out of OVLT vessels –> bind receptors on adluminal surface of capillary EC in OVLT –> EC’s upregulate COX –> PGE2 –> WSNs –> decreases WSN discharge rate –> CSNs disinhibited –> higher temp set point –> fever
how to anti-pyretics stop a fever?
inhibit COX w/i the OVLT epithelium
less production of PGE2 –> restores WSN activity
what causes hot-flashes?
high density of estrogen receptors at POAH
get hotflashes w/ estrogen decline
paraventricular (PVN) and supraoptic n. (SON) release what?
magnocellular neurons –> ADH + oxytocin
what does the suprachiasmatic n do?
regulates circadian rhythms
what happens if you have a lesion in the ventromedial nucleus (VMN)?
over-eating
irritability
aggression
what is the only place in the brain that uses histamine?
tubermammillary nucleus
histamine release critical for cortical activation
what does the mamillary body do?
memory circuit relay
short-term memory
what degenerates early in Alzheimer’s Disease?
hippocampus
hippocampus –> fornix –> mammillary bodies (short-term memory)
what does african sleeping sickness affect?
trypanosomes infect suprachiasmatic n.
what does narcolepsy affect?
genetic mutation
affects orexin receptor
what does a tumor to the lateral n. cause?
hypophagia
what does a tumor to the posterior n cause?
poikilothermia (can’t conserve heat) = hypothermia
what does a lesion to POAH cause?
hyperthermia
what does a lesion to the anterior region of the hypothalamus cause?
inhibition of ADH secretion
diabetes insipidus
