Hypothalamus Flashcards
function of the hypothalamus?
- main: homeostasis
- regulate ANS (ascending and descending tracts)
- control body temperature, hunger, thirst, fatigue, sleep, and circadian rhythms
Via which structure does the hypothalamus link the nervous system to the endocrine system?
pituitary gland
What are the inputs to the hypothalamus?
- 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
lateral hypothalamic nuclei vs ventromedial hypothalamic nuclei?
- lateral: controls desire to eat and drink
- ventromedial: controls desire to STOP eating and drinking (satiety center)
lesion to lateral hypothalamic nuclei
aphagia and adipsia (lose desire to eat)
lesion to ventromedial hypothalamic nuclei
abnormally increased food intake (lose desire to STOP eating)
What are the hypothalamic efferents?
- pituitary gland: hormone production
- autonomic nervous system: control internal organs
- limbic system: instinctual motor behaviour (e.g. eating)
The hypothalamus is where the _____________ and ______________ systems unite.
autonomic, endocrine
Which part of the pituitary gland is hormone producing? Releasing?
- producing = adenohypophysis
- releasing = neurohypophsis
Which nucleus synthesizes oxytocin? Which part of the pituitary gland does it release to?
- posterior pituitary
- paraventricular nucleus
function of oxytocin in males
smooth muscle contraction in prostate gland
Which nucleus synthesizes ADH/AVP? Which part of the pituitary gland does it release to?
- posterior pituitary
- supraoptic nucleus (SON)
which part of the hypothalamus are the supraoptic and paraventricular nuclei located? Via which tract are they connected to the pituitary?
- medial hypothalamus
- hypothalamo-hypophyseal tract
Describe the hypophyseal portal system.
- 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
Describe the HPA axis
- control release of cortisol
- cortisol raises blood sugar; prevent insulin function and promote gluconeogenesis
- cortisol released in response to stress (to boost energy)
hyperplasia vs hypertrophy
- hyperplasia = increase in number
- hypertrophy = increase in size
gigantism vs acromegaly (cause and result)
- gigantism: excessive GH BEFORE PUBERTY; can be mentally slow
- acromegaly: excessive GH AFTER PUBERTY; shortens life expectancy
gigantism vs acromegaly (characteristics)
- gigantism: excessive length of bones; coarse facial bones
- acromegaly: thick and coarse bones; large lips, nose, jaw; thick tongue and skin
How can a pituitary tumor affect vision?
- bitemporal hemianopsia
- due to compression of optic chiasm (and carotid artery)
another name for pineal gland?
epiphysis
function of pineal gland? (what does it produce)
production of melatonin in absence of light stimulation
How is melatonin released (i.e. describe the path)?
- 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
How is the circadian rhythm endogenously controlled?
clock genes
How is the circadian rhythm exogenously controlled?
- light regulation of SCN to pineal gland
- clock genes regulated by light exposure
