Lecture 47: Hypothalamus

Question 1

Hypothalamus regulates (6)

Answer 1

Homeostasis, temperature, hunger/thirst, emotional states, circadian rhythms/sleep/wake, reproduction

Question 2

Preoptic area and anterior hypothalamus functions (4)

Answer 2

Thermoregulation (fever is generated here), fluid/electrolyte balance, sexual behavior, sleep!

Question 3

The ventrolateral preoptic area is crucial for…

Answer 3

Sleep

Question 4

Suprachiasmic nucleus is important for…this is based on what cycle?

Answer 4

Circadian rhythms; light/dark cycle

Question 5

Arcuate nucleus

Answer 5

Feeding/body weight via NPY, AgRP, alphaMSH; neuroendocrine via DA (prolactin), GHRH (growth hormone)

Question 6

Where do we find magnocellular neurons? What do they do?

Answer 6

Paraventricular and supraoptic nuclei; make oxytocin and vasopression and project directly to the posterior pituitary

Question 7

Where do we find parvocellular neurons? What do they do?

Answer 7

Paraventricular nucleus; make “releasing factors” to influence the anterior pituitary: CRF, TRF, GnRF

Question 8

Medial hypothalamus (feeding)

Answer 8

Satiety center (reduces feeding)

Question 9

Lateral hypothalamus (feeding + 1 function)

Answer 9

Activates feeding and sleep-wakefulness (makes Orexin)

Question 10

Ventromedial hypothalamus (feeding + 2 functions)

Answer 10

Reduces feeding; thermoregulation and sexual functions

Question 11

Mammillary nuclei

Answer 11

Memory

Question 12

What is the sole source of histamine in the brain?

Answer 12

Tuberomammillary nucleus

Question 13

Most important brain inputs from cortex to hypothalamus (2)

Answer 13

Inhibitory from hippocampus and excitatory from amygdala

Question 14

ANS inputs to hypothalamus (2)

Answer 14

Nucleus of the solitary tract and reticular formation

Question 15

ANS outputs from hypothalamus

Answer 15

Medulla (parasymp = vagal nuclei) and spinal cord (preganglionic sympa = intermediolateral nucleus)

Question 16

Suprachiasmatic nucleus is innervated by the…where does it send output? Then where? What does light do?

Answer 16

Optic nerve; superior cervical ganglion (sympa); activates pineal gland to release melatonin; TURNS OFF melatonin synthesis

Question 17

All of the neuroendocrine and pre-autonomic neurons of the hypothalamus are innervated by what nucleus?

Answer 17

SCN

Question 18

T/F: The molecular circadian clock is only located in the SCN

Answer 18

False: these molecules are present all over the body, it is just controlled by light in the SCN (hence, circdian rhythms)

Question 19

Orexin is expressed solely in the…promotes…is also…

Answer 19

Lateral hypothalamus; wakefulness, arousal, reward; pro-feeding

Question 20

Name two TF and one gene that regulates our circadian rhythms and describe

Answer 20

TF: Clock+Bmal and Period; Period inhibits Clock+Bmal and then neg feedbacks to inhibit itself; Period protein is degraded w/ a 24 hour cycle

Question 21

Sleep appears to be essential for…

Answer 21

Memory consolidation

Question 22

Sleep is thought to be initiated by…NT? Turns off (nuclei)?

Answer 22

Ventrolateral preoptic area (GABA); orexin (LH) and histamine (TMN)

Question 23

Orexin and histamine usually project to…What do these usually do? Then what?

Answer 23

Monoamine and cholinergic nerve cells that provide major activation to thalamus; intrinsic circuits = large waves

Question 24

Describe REM (NT?) and what turns this on? NT? Why does this not happen during the day?

Answer 24

Series of brainstem cholinergic cells (REM-on) become activated and trigger sensory input into thalamus (REM waves); LOSS of REM-off cells (monoamine); REM-off cells are normally activated by Orexin

Question 25

What chemical builds during wakefulness that might trigger the VLPO?

Answer 25

Adenosine

Question 26

Describe relationship between thermoregulation and sleep

Answer 26

Body cools at night and heats during the day; VLPO is involved in thermoregulation –> warming VLPO induces NREM sleep