Hypothalamus

Question 1

Tracts that relay neural info from the hypothalamus to the SNS

Answer 1

1. Dorsal longitudinal fasiculus
2. Medial forebrain bundle
3. Mammillotegmental tract

Question 2

Direct vs Indirect pituitary pathways

Answer 2

Direct:
Posterior
(ADH/vasopressin + oxytocin)
- made by SON/PVN, and stored in terminals until they release DIRECTLY into general circulation

Indirect:
Anterior pituitary
- Hormones made by anterior pituitary –> released into hypothalamopituitary portal circ –> Ant. Pit regulate release of these hormones from peripheral endocrine organs

Question 3

Lesion of which part of the hypothalamus results in aggressive behavior, and which for placid behavior?

Answer 3

Aggressive:
- medial hypothalamus

Placid:
- lateral hypothalmic tract + mamillary region

Question 4

When the hypothalamus is disconnected from higher brain areas, but remains connected to brainstem and SC, what behavior is seen?

Answer 4

Extreme aggression, irritation over inappropriate stimuli

SHAM RAGE

Question 5

Disconnecting hypothalamus from brainstem does what to behavior?

Answer 5

abolishes sham rage

Question 6

Which is designated to tell you that your body is too hot vs too cold?
- Ant vs post hypothalamus

Answer 6

Anterior:
tell you, that you are too hot
- lesion = hyperthermia

Posterior:
too cold
- lesion = hypothermia

Question 7

Which hormone increases resting rate of heat production?

Answer 7

Thyroxin increases basal heat production

Question 8

Brown fat in babies important why?

Answer 8

NE is released by brown fat cells by symp nerve fibers.
–> allows for uncoupled oxidative phosphorylation
(nonshivering thermogenesis to fight hypothermia)

Question 9

How does the hypothalamus regulate thirst and sweat?

Answer 9

Aldosterone: promote reabsorption of Na+ from sweat

Greater thirst (blood is hypertonic sooner)

Question 10

Role of PAOH on the posterior hypothalamus?

Answer 10

Inhibits

PAOH is tonically active at nL body temp
- Firing rate of POAH cells depend on local temperature is PAOH

Question 11

What happens to POAH cells when temp drops below a set point?

Answer 11

POAH inhibits posterior hypothalamus

Inhibiting POAH would reduce their firing rate –>
releasing post. hypothalamus from cells from inhibition.
- greatly potentiating heat gain.

(normally POAH would respond to higher body temps by increaseing firing rate above normal, pt feels hot, and sweats until body temp falls)

Question 12

Satiety center

Answer 12

Ventromedial nucleus

Question 13

Primnary circadian clock in body

Answer 13

Suprachiasmatic nucleus (SCN)