hypothalamus

Question 1

What nucleus of the hypothalamus is responsible for thermoregulation? What happens during fever?

Answer 1

The preoptic area in the anterior hypothalamus. During fever, macrophages secrete cytokines IL6 and IL1 which activate prostaglandins in the preoptic area, raising the temperature set point of the body

Question 2

What nucleus of the hypothalamus is responsible for the regulation of feeding, drinking and body weight by reducing the drive to feed?

Answer 2

ventromedial nucleus and dorsomedial nucleus

Question 3

What nucleus of the hypothalamus mediates circadian rhythms according to light and dark cycles?

Answer 3

suprachiasmatic nucleus

Question 4

What are the inputs to the suprachiasmatic nucleus? What are the outputs?

Answer 4

Inputs: optic nerve (directly and from thalamic relays)
Outputs: paraventricular and supraoptic nuclei, influencing neuroendocrine function; superior cervical sympathetic ganglion which innervate the pineal gland to release melatonin; important pre-autonomic neurons

Question 5

What nucleus in the hypothalamus is responsible for releasing all the feeding peptides (neuropeptide Y, alpha-MSH)?

Answer 5

Arcuate nucleus (aka infundibulum)

Question 6

What nucleus in the hypothalamus regulates the secretion of prolactin from the anterior pituitary?

Answer 6

arcuate nucleus

Question 7

What nucleus in the hypothalamus secretes growth hormone releasing factor?

Answer 7

arcuate nucleus

Question 8

What area of the hypothalamus regulates fluid and electrolyte balance?

Answer 8

anterior hypothalamus

Question 9

What area of the hypothalamus regulates sexual behavior?

Answer 9

anterior hypothalamus

Question 10

What do magnocellular cells secrete? What do parvocellular cells secrete? Where do they secrete those substances?

Answer 10

magnocellular - makes and releases anti-diuretic hormone and/or oxytocin from nerve terminals in the posterior pituitary into the systemic circulation
parvocellular - make and release various tropic hormones (releasing factors) into the pituitary portal system

Question 11

How does the hypothalamus regulate the autonomic system? What are the inputs that control the hypothalamus-ANS axis?

Answer 11

The hypothalamus innervates the vagal nuclei and indirectly innervates the preganglionic sympathetic neurons in the intermediolateral nucleus of the spinal cord
Inputs: nucleus of the solitary tract, the reticular formation

Question 12

What function is the reticular formation involved in?

Answer 12

arousal

Question 13

Where are neurons that release orexin? Where do these neurons project to? What is the function of orexin?

Answer 13

lateral hypothalamus
Project to 1) histamine neurons in the tuberomammillary nucleus
2) norepinephrine and serotonin neurons in the locus ceruleus and dorsal raphe
3) dopamine neurons in the ventral segmental area
Function in promoting wakefulness, arousal and motivation

Question 14

What is the function of the ventrolateral preoptic area of the anterior hypothalamus?

Answer 14

Triggers NREM sleep

Question 15

How does the brain switch from NREM to REM sleep?

Answer 15

At some point in NREM, monoamin-ergic “REM-off” neurons stop firing. This triggers the activation of “REM-on” neurons in the PPT/LDT (pedunculopontine tegmentum/laterodorsal tegmentum). The “REM-on” neurons drive thalamic neurons which are responsible for the characteristic EEG waves of REM sleep

Question 16

How does adenosine influence sleep?

Answer 16

Adenosine builds up during waking hours in the ventrolateral preoptic area and declines during sleep.

Question 17

What is the cause of narcolepsy?

Answer 17

autoimmune destruction of orexin neurons in the lateral hypothalamus

Question 18

What hormones do the magnocellular neurons in the paraventricular nucleus make? What hormones do the magnocellular neurons in the supraoptic nucleus make?

Answer 18

paraventricular - BOTH oxytocin and ADH

supraoptic nucleus - only ADH