Hypothalamus (3-26-14)

Question 1

what does the OVLT (organum vasoculosum of the lamina terminalis) do?

Answer 1

trigger febrile responses

osmoreceptors

Question 2

what does the median eminence do?

Answer 2

release hypothysiotropic hormones into portal system –> adenohypophysis

Question 3

what does the neurohypophysis do?

Answer 3

it’s where the axons of supraoptic and paraventricular neurons RELEASE ADH/OXYTOCIN

Question 4

what does the SFO (subfornical organ) do?

Answer 4

osmoreceptors for blood/CSF osmolarity

Question 5

what does the area posterma do?

Answer 5

chemoreceptors for noxious substances in blood

Emetic center

Question 6

what does the pineal gland do?

Answer 6

melatonin secretion –> circadian rhythms

Question 7

what does the medial preoptic nucleus do?

Answer 7

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)

Question 8

what does the lateral preoptic nucleus do?

Answer 8

sleep onset (non-REM stages)

Question 9

anterior hypothalamic lesions cause…

Answer 9

hyperthermia

Question 10

posterior hypothalamic lesions cause…

Answer 10

hypothermia

Question 11

explain how a fever happens

Answer 11

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

Question 12

how to anti-pyretics stop a fever?

Answer 12

inhibit COX w/i the OVLT epithelium

less production of PGE2 –> restores WSN activity

Question 13

what causes hot-flashes?

Answer 13

high density of estrogen receptors at POAH

get hotflashes w/ estrogen decline

Question 14

paraventricular (PVN) and supraoptic n. (SON) release what?

Answer 14

magnocellular neurons –> ADH + oxytocin

Question 15

what does the suprachiasmatic n do?

Answer 15

regulates circadian rhythms

Question 16

what happens if you have a lesion in the ventromedial nucleus (VMN)?

Answer 16

over-eating
irritability
aggression

Question 17

what is the only place in the brain that uses histamine?

Answer 17

tubermammillary nucleus

histamine release critical for cortical activation

Question 18

what does the mamillary body do?

Answer 18

memory circuit relay

short-term memory

Question 19

what degenerates early in Alzheimer’s Disease?

Answer 19

hippocampus

hippocampus –> fornix –> mammillary bodies (short-term memory)

Question 20

what does african sleeping sickness affect?

Answer 20

trypanosomes infect suprachiasmatic n.

Question 21

what does narcolepsy affect?

Answer 21

genetic mutation

affects orexin receptor

Question 22

what does a tumor to the lateral n. cause?

Answer 22

hypophagia

Question 23

what does a tumor to the posterior n cause?

Answer 23

poikilothermia (can’t conserve heat) = hypothermia

Question 24

what does a lesion to POAH cause?

Answer 24

hyperthermia

Question 25

what does a lesion to the anterior region of the hypothalamus cause?

Answer 25

inhibition of ADH secretion

diabetes insipidus