Thalamus and Hypothalamus Flashcards
suprachiasmatic nucleus of hypothalamus
*transduces the light-dark cycle established by the sun to neural signals
*input from retina
*output via several hypothalamic nuclei
*increased activity of the suprachiasmatic nuclei INHIBITS melatonin production by the pineal gland via ANS
what hormones modulate the hypothalamic control of eating
1) ghrelin
2) leptin
ghrelin
*hormone from stomach that stimulates hunger
leptin
*long-term hormone secreted by fat that leads to decreased hunger and increased satiety (tells you when you are full)
posterior pituitary
*contains axon terminals
*hormones synthesized by the hypothalamus are stored in the posterior pituitary and released directly into blood supply
*ADH and oxytocin
anterior pituitary
*contains cells that synthesize hormones
*activated by hypothalamic releasing hormones
*releases “tropic” hormones that act on glands and tissues (FLAT PeG hormones)
*FSH, LH, ACTH, TSH, prolactin, GH
ACTH physiological effect
response to stress
TSH physiological effects
modulates metabolism
GH physiological effects
promotes growth
prolactin physiological effects
milk let down
FSH physiological effects
spermatogenesis
follicle growth/ovulation
LH physiological effects
egg release/ovulation
spermatogenesis
VPL nucleus (of thalamus) - information
all sensory information (pain, temperature, touch, proprioception, vibration) from the body
*VPL = ventral posterolateral nucleus
VPL nucleus (of thalamus) - input
*spinothalamic and dorsal column/medial lemniscus tracts
*all sensation from the body (pain, temperature, vibration, proprioception) is integrated into the thalamus
VPL (of thalamus) - output
somatosensory cortex
VPM (of thalamus) information
- sensory information from face (via trigeminal nerve)
- taste
VPM (of thalamus) input
trigeminal nerve
gustatory fibers
VPM (of thalamus) output
somatosensory cortex
LGN (of thalamus) information
vision
LGN = lateral geniculate nucleus
LGN (of thalamus) input
optic nerve (CN II)
LGN (of thalamus) output
calcarine fissure in occipital cortex
MGN (of thalamus) information
hearing
MGN = medial geniculate nucleus
MGN (of thalamus) input
superior olive & inferior colliculus (hearing information)
MGN (of thalamus) output
auditory cortex in temporal lobe
ventrolateral nucleus (VL) of thalamus - information
motor
ventrolateral nucleus (VL) of thalamus - input
basal ganglia
ventrolateral nucleus (VL) of thalamus - output
motor cortex
thalamic syndrome
*occurs when a lesion destroys the thalamus
*CONTRALATERAL PURE sensory loss (face, arm, and leg; all sensory modalities lost)
specific inputs to thalamus
inputs that are reliably relayed to cortex (inputs to VPL, VPM, LGN, MGN, etc)
regulatory inputs to thalamus
inputs that contribute to decisions about what form of information leaves the thalamus (cortical inputs and reticular nucleus)
outputs of thalamus
*largely excitatory to cortex
*local inhibitory circuits projecting to thalamic nuclei
thalamic reticular nucleus
*a sheet of GABAergic (inhibitory) neurons that receives input from cortex and other thalamic nuclei
*does NOT project to cortex
*important source of regulatory input to nuclei in the thalamus
general functions of hypothalamus (HEAL)
homeostasis, endocrine, autonomic, and limbic expression
specific functions of hypothalamus (TANHATS)
-thirst and water balance
-adenohypophysis control (anterior pituitary)
-neurohypophysis control (posterior pituitary)
-hormones and hunger
-autonomic regulation
-temperature regulation
-sexual expression
paraventricular and dorsal medial nuclei of hypothalamus - function
drive ANS function
paraventricular and supraoptic nuclei of hypothalamus - function
posterior pituitary function (synthesize ADH and oxytocin, the 2 hormones released by the posterior pituitary)
mammillary bodies of hypothalamus - function
limbic system
suprachiasmatic nucleus of hypothalamus - function
circadian rhythym
lateral hypothalamus - function
hunger (appetite generation - stimulated by ghrelin)
medial hypothalamus - function
satiety (appetite suppression - stimulated by leptin)
anterior hypothalamus - function
cooling (heat dissipation; vasodilation of vessels so heat will be lost)
note - this is what is affected by circulating pyrogens, leading to fever
posterior hypothalamus - function
heating (heat conservation; vasoconstriction of vessels so heat is retained)
OVLT (organum vasculosum of lamina terminalis)
*a group of cells with access to blood-brain barrier
*evaluates blood osmolarity and circulating pyrogens
*feeds information about blood to hypothalamus
SFO (subfornical organ)
*a group of cells with access to blood-brain barrier
*evaluates blood osmolarity and many hormones
*feeds information about blood to hypothalamus
SCO (subcommissural organ)
*a group of cells with access to blood-brain barrier
*evaluates osmoregulation
*feeds information about blood to hypothalamus
area postrema
*a group of cells with access to blood-brain barrier
*evaluates toxins in blood and many hormones to cause vomiting if necessary (ex alcohol poisoning)
*feeds information about blood to hypothalamus
