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23 Cards in this Set
- Front
- Back
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Hypothalamus Function
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- maintain homeostasis
subserves 3 systems 1. ANS 2. endocrine 3. Limbic |
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Hypothalamic Nuclei
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1. medial preoptic nucleus
2. Suprachiasmatic |
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Medial Preoptic Nucleus
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- regulates gonadotropic hormone release from adenohypophysis
- contains the sexually dimorphic nucleus, development of which depends on testosterone levels |
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Suprachiasmatic Nucleus
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- direct input form retina
- regulates circadian rhythms |
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Anterior Nucleus
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- thermal regulation (disspiation of heat)
- stimualtes PSNS - destruction results in hyperthermia |
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Paraventricular Nucleus
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- synthesizes ADH, oxytocin & Corticotropin-Releasing hormone
- starts the supraopticohypophyseal tract which projects to neurohypophysis. regulates water balance and project directly to Autonomic nuclei of brainstem & all levels of spinal cord - destruction results in Diabetes insipidus |
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Dorsomedial Nucleus
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stimulation results in obesity & savage behaviour
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Posterior Nucleus
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- thermal regulation (conservation of heat)
- destruction results in inability to thermoregulate - stimulates the SNS |
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Lateral Nucleus
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Stimulation induces eating
destruction results in starvation |
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Mamillary Body
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- input from hippocampal formation via fornix
- projects to anterior nucleus of thalamus - contains hemorrhagic lesions in wernicke's encephalopathy |
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Ventromedial Nucleus
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Satiety center
- destruction results in obesity & savage behaviour |
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Arcuate Nucleus
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- produces hypothalamic releasing factors
- contains DOPA-ergic neurons that inhibit prolactin release |
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Supraoptic Nucleus
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Synthesizes ADH & oxytocin
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Hypophyseal Portal System
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Major Fibres Systems in Hypothalamus
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1. fornix; from hipocampal formation to mamillary nucleus, anterior nucleus of thalamus & septal area. then from the fornix back to the hippocampal formation
2. medial forebrain bundle; traverses entire lateral hypothalamic area. interconnects orbitofrontal cortex, septal area, hypothalamus & amygdala 3. Mamillothalamic Tract; mamillary to anterior nucleus of thalamus (papez circuit) 4. Stria terminalis; interconnects septal area, hypothalamus & amygdala 5. Supraopticohypophysial tract; supraoptic & paraventricular nuclei to neurohypophysis release site for ADH & Oxytocin 6. Tuberohypophysial tract; conducts the arcuate nucleus to the hypophyseal portal systme 7. Hypothalamospinal tract; direct descending autonomic fibres. |
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Autonomic Functions
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1. Anterior hypothalamus excites PSNS
2. Post. SNS |
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Temperature Regulation
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1. Ant. hypothalamus maintians body temp
2. Post. helps produce & conserve heat |
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Water balance regulation
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- paraventricular n. synthesisi ADJ controlling water excretion by the kidneys
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Food Intake regulation
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1. VM nuleus when stimulated inhibits urge to eat
2. L. induces urge to eat when stimulated |
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Diabetes Insipidus
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-polyuria & polydipsia
- lesion of the ADH pathways to the post. lobe of pituitary gland |
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SIADHS
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usually caused by lung tumor or drug therapy (carbamazepine, chlorpromazine)
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Craniopharyngioma
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- congenital tumor that originates from remnants of Rathke's pouch. usually calcified
1. pressure on chiasma (bitemporal) 2, pressure on the hypothalamus; hypothalamic syndrome (adiposity, diabetes insipidus, disturbace of temp regulation & somnolence) |
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Pituitary Adenomas
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- can cause endocrine abnormalities (emenorrhea & galactorrheas)
1. pressure on chiasma (bitemporal) 2, pressure on the hypothalamus; hypothalamic syndrome (adiposity, diabetes insipidus, disturbace of temp regulation & somnolence) |
