Hypothalamus nuclei Flashcards
Posterior nucleus (po)
Sympathetic ns control (contributes to descending fibers of IML)
Thermogenesis (vasoconstriction, shivering)
Lesion= Horner’s, poikilothermia
Tuberomammillary Nucleus
Control wakefulness via histaminergic neurons that project all over
Lesion = hypersomnia
Mammillary body (mb)
Memory consolidation
Papez’s circuit of limbic system (hippocampus—fornix—mb—MTT—anterior nucleus of thalamus—cingulate gyrus—cingulum—hippocampus)
Lesion=
Wernicke encephalopathy in acute phase (ocular palsies, ataxic gait, confusion)
Korsakoff Syndrome (anterograde amnesia and confabulation)
Both can be due to T1 thiamine deficiency and alcoholism as well
Dorsomedial nucleus (dm)
[tuberal]
Feeding and weight control center
Connects with other nuclei of tuberal region to reg feeding behavior
Ventromedial nucleus (vm)
[tuberal region]
Satiety center
Leptin-sensitive neurons promote anorexigenic effects. Leptin is released by adipocytes and its circulation reflects body fat stores. High nutrient= incr. leptin = decr. appetite
Lesion= hyperphagia and obesity
Arcuate Nucleus (ar)
[tuberal region]
Releases DA, GHRH, and controls feeding behavior.
DA= inhibit secretion of prolactin from anterior pituitary
GHRH= stimulates GH secretion from ant. pituitary
Contains neurons sensitive to leptin, grehlin, and orexin
Lateral Hypothalamus
[tuberal region]
Feeding Center; Sleep/wake regulator
Its stimulation promotes hunger and feeding.
Contains neurons that secrete orexin/hypocretin, which regulates sleep/wake AND feeding AND reward
Lesion: Anorexia, aphagia, weight loss. If orexin deficient= narcolepsy.
Supraoptic Nucleus
[anterior supraoptic]
Secrete ADH/vasopressin to promote water retention
Secrete oxytocin to promote milk letdown and uterine contraction
Paraventricular nucleus
[anterior supraoptic]
Secretes ADH and oxytocin
Releases CRH, TRH, and somatostatin/SRIF (COAST)
Somatostatin/SRIF inhibits GH secretion and TSH from anterior pituitary (note: Arcuate nucleus promotes GH by releasing GHRH)
Lesion: Diabetes insipidus (polydypsia, polyuria, NO hypergylcemia)
Anterior Nucleus
[anterior supraoptic]
Thermolysis
(vasodilation and sweating)
Controls parasympathetic system by contributing descending hypothalamic fibers that control CN III, VII, IX, X and IML S2-4
Lesion: mydriasis?, hyperthermia
Suprachiasmatic nucleus
[anterior supraoptic]
Biological clock, regulates Circadian Rhythm; Modulates pineal gland and its melatonin output
Receives light info from retinal ganglion via retinohypothalamic tract to adjust 25hr clock to 24. Light info relayed by descending sympathetic fibers eventually reach pineal gland, inhibiting melatonin production.
Lesion: Disturbance in cyclic variations of bodily functions like BP, hormones, body temp, sleep, wakefulness
Medial Preoptic Nucleus (mpr)
[anterior preoptic]
Thermoregulation set point
Releases Gonadotropin-releasing hormone.
Can activate posterior nucleus for thermogenesis or activate the anterior nucleus for thermolysis.
GnRH stimulates LH+FSH. Cyclic release of GnRH in females, continual in males.
Lesion= Hyperthermia, amenorrhea and impotence.
Fever a result of immune system stimulating production of PGE2 act on mpr to set set-point higher than normal, and subsequent activation of the posterior nucleus. Aspirin and NSAIDs inhibit cyclooxygenase involved in PGE2 production, reducing fever.
Lateral Preoptic Nucleus
Promotes non-REM sleep (by ventral lateral preoptic nucleus)
Controls global brain activity
GABAergic neurons in VLPO inhibit orexinergic neurons in lateral hypothalamus, histaminergic neurons in posterior hypothalamus, and cholinergic, serotinergic, and noradrengergic neruosn in brainstem)
Lesion: hyposomnia
