Hypothalamus

Question 1

function of the hypothalamus?

Answer 1

• main: homeostasis
• regulate ANS (ascending and descending tracts)
• control body temperature, hunger, thirst, fatigue, sleep, and circadian rhythms

Question 2

Via which structure does the hypothalamus link the nervous system to the endocrine system?

Answer 2

pituitary gland

Question 3

What are the inputs to the hypothalamus?

Answer 3

• NTS: visceral sensory info (CN IX, X)
• Reticular Formation: info about skin temperature
• Retina: optic nerve to SCN; circadian rhythm
• Limbic system (hippocampus, amygdala, olfactory cortex): eating and reproduction
• intrinsic receptors: thermoreceptors and osmoreceptors to monitor temperature and ionic balance

Question 4

lateral hypothalamic nuclei vs ventromedial hypothalamic nuclei?

Answer 4

• lateral: controls desire to eat and drink
• ventromedial: controls desire to STOP eating and drinking (satiety center)

Question 5

lesion to lateral hypothalamic nuclei

Answer 5

aphagia and adipsia (lose desire to eat)

Question 6

lesion to ventromedial hypothalamic nuclei

Answer 6

abnormally increased food intake (lose desire to STOP eating)

Question 7

What are the hypothalamic efferents?

Answer 7

• pituitary gland: hormone production
• autonomic nervous system: control internal organs
• limbic system: instinctual motor behaviour (e.g. eating)

Question 8

The hypothalamus is where the _____________ and ______________ systems unite.

Answer 8

autonomic, endocrine

Question 9

Which part of the pituitary gland is hormone producing? Releasing?

Answer 9

• producing = adenohypophysis
• releasing = neurohypophsis

Question 10

Which nucleus synthesizes oxytocin? Which part of the pituitary gland does it release to?

Answer 10

• posterior pituitary
• paraventricular nucleus

Question 11

function of oxytocin in males

Answer 11

smooth muscle contraction in prostate gland

Question 12

Which nucleus synthesizes ADH/AVP? Which part of the pituitary gland does it release to?

Answer 12

• posterior pituitary
• supraoptic nucleus (SON)

Question 13

which part of the hypothalamus are the supraoptic and paraventricular nuclei located? Via which tract are they connected to the pituitary?

Answer 13

• medial hypothalamus
• hypothalamo-hypophyseal tract

Question 14

Describe the hypophyseal portal system.

Answer 14

• superior hypophyseal artery supplies anterior pituitary
• goes through median eminence
• vessels between median eminence and ant pit carry blood from one capillary network to another (portal system)
• in the ant pit: vessels from a secondary capillary network among endocrine cells

Question 15

Describe the HPA axis

Answer 15

• control release of cortisol
• cortisol raises blood sugar; prevent insulin function and promote gluconeogenesis
• cortisol released in response to stress (to boost energy)

Question 16

hyperplasia vs hypertrophy

Answer 16

• hyperplasia = increase in number
• hypertrophy = increase in size

Question 17

gigantism vs acromegaly (cause and result)

Answer 17

• gigantism: excessive GH BEFORE PUBERTY; can be mentally slow
• acromegaly: excessive GH AFTER PUBERTY; shortens life expectancy

Question 18

gigantism vs acromegaly (characteristics)

Answer 18

• gigantism: excessive length of bones; coarse facial bones
• acromegaly: thick and coarse bones; large lips, nose, jaw; thick tongue and skin

Question 19

How can a pituitary tumor affect vision?

Answer 19

• bitemporal hemianopsia
• due to compression of optic chiasm (and carotid artery)

Question 20

another name for pineal gland?

Answer 20

epiphysis

Question 21

function of pineal gland? (what does it produce)

Answer 21

production of melatonin in absence of light stimulation

Question 22

How is melatonin released (i.e. describe the path)?

Answer 22

• retinal axons project to SCN of hypothalamus (retinohypothalamic tract)
• SCN sends signals, via sympathetic nervous system, to pineal gland
• signals INHIBIT production of melatonin by pineal gland
• at night, no light –> impulses from SCN stop –> melatonin released

Question 23

How is the circadian rhythm endogenously controlled?

Answer 23

clock genes

Question 24

How is the circadian rhythm exogenously controlled?

Answer 24

• light regulation of SCN to pineal gland
• clock genes regulated by light exposure