Lecture 08 - Hypothalamus

Question 1

Hypothalamic inputs

Answer 1

Viscerosensory 
internal receptors ** homeostasis
retina
olfactory
amygdala ** physical expression of emotion
hippocampus

Question 2

Circumventricular organs

Answer 2

fenestrated endothelial cells - part of BBB

-constantly monitor blood

Question 3

Outputs

Answer 3

descending autonomics –> drive sympathetics

“head ganglion of the autonomic nervous system”

Question 4

Regulation of endocrine system

Answer 4

Pituitary gland

also affects periphery via neuroendocrine system

Question 5

Venous drainage

Answer 5

int. jugular

Question 6

Regions

Answer 6

Mammillary region
tuberal region
supraoptic region

Question 7

Paraventricular nucleus

Answer 7

Supraoptic region

• synthesize and secrete oxytocin and ADH –> post pit.
• oxytocin = uterine contractions, milk let-down, maternal bonding
• ADH = increase H2O reabsorption and increase BP
• CRF = release of cortisol from adrenal cortex (via portal system) –> increases energy demand and increases GNG

Question 8

Supraoptic nucleus

Answer 8

Supraoptic region

-synthesize and secrete oxytocin and ADH, not CRF

Question 9

Suprachiasmatic nucleus

Answer 9

Supraoptic region
-master of biological clock
inhibition decreases release of melatonin from pineal gland
darkness dis-inhibits = increase melatonin release

Question 10

Melatonin

Answer 10

• release inhibited by light

- increased levels cause drowsiness, lower body temp

Question 11

Seasonal affective disorder

Answer 11

SAD (late fall, early winter)

• symptoms: sluggish, anxiety, oversleeping, craving carbs, lethargy, depression
• treat by increased exposure to broad spectrum light (blue light) to suppress melatonin

Question 12

Anterior hypothalamus

Answer 12

Supraoptic region

• necessary for heat dissipation (thermoregulation)
• descending autonomic arousal = sweating, vasodilation, panting

***lesion = hyperthermia
(aneurism in Ant. comm.)

Question 13

Arcuate nucleus

Answer 13

Tuberal region

-Thyroid RH, CRF, Gonadotropin RH, Growth hormone RH, somatostatin (inhibits GH)

Question 14

Ventromedial nucleus

Answer 14

Tuberal region
-satiety center

***lesion = hyperphagia (overeating), also rage-like outbursts (hypothalamic rage)

Question 15

Leptin

Answer 15

neuropeptide secreted by adipocytes that bind to receptors in ventromedial nucleus to crub appetite

• deficiency results in morbid obesity
• reduced sensitivity to leptins may contribute to obesity

Question 16

Lateral hypothalamic area (LHA)

Answer 16

“feeding center”

***lesion = aphagia (severe neglect of eating)

Medial forebrain bundle –> dopaminergic highway for rewards system, but also –> LHA

Question 17

Orexin/Hypocretin

Answer 17

Excitatory neuropeptide secreted by lateral hypothalamus

• energy surge, increased arousal
• increases body temp, locomotion, respiration
• promotes wakefulness
• increases appetite

Neurons manage metabolic states during alert, active states and sleep (energy balance)

• highly active states require increased food
• monitor nutrional status to stimulate arousal and appetite when levels fall below set point
• dynamic between LHA and VMN to establish set point for body weight

Question 18

Posterior hypothalamus

Answer 18

Mammillary region

• Head production, vasoconstriction, piloerection, shivering
• descending autonomics –> sympathetic drive

***lesion = hypothermia

Question 19

Mammillary body

Answer 19

Mammillary region
-part of limbic system (limbic -> hippo -> fornix -> MB)

***lesion = Karsakoff’s psychosis (problem with timeline of memories -> temporal encoding rather than retrieval)