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Hypothalamus 15 apr 2016

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Hypothalamus 15 apr 2016

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Hypothalamus 15 apr 2016

  1. 1. Hypothalamus Madanmohan and Jai Ganesh Department of Physiology, MGMC & RI
  2. 2. Hypothalamus: introduction • Below thalamus • Forms lower lateral wall and floor of 3rd ventricle • Each side: preoptic, supraoptic, tuberal and mammillary areas • Many smaller nuclei, diverse functions.
  3. 3. Learning objectives • Name the nuclei of hypothalamus. • Name their afferent and efferent connections. • Briefly describe the role of hypothalamus in regulation of: 1. autonomic nervous system and homeostasis 2. secretion of hormones of anterior pituitary 3. body temperature 4. food intake 5. water intake • State the causes and consequences of disordered hypothalamic function
  4. 4. Location of hypothalamus
  5. 5. Nuclei of hypothalamus
  6. 6. Hypothalamus: functions 1. Cyclic phenomena, biological clock: circadian (24 h) rhythm, e.g. sleep-wake cycle. 2. Autonomic nervous system, visceral function. 3. Endocrine: anterior pituitary – releasing Hs posterior pituitary hormones 4. Emotional, reproductive and maternal behavior. 5. Regulation of body temperature. 6. Regulation of food and water intake.
  7. 7. Circadian (24 h) rhythms Suprachiasmatic nucleus: endogenous biological clock Sleep-wake cycle. Ventrolateral preoptic area: facilitates sleep Posterior hypothalamus: waking centre
  8. 8. Autonomic control Head ganglion Anterior hypothalamus: parasymp. responses Posterior hypothalamus: symp. responses Regulation of visceral functions: homeostasis
  9. 9. Endocrine function Ant. pituitary releasing & inhibiting hormones: CRH GHRH GHIH TRH PRH PIH GnRH Post. Pituitary: ADH, oxytocin
  10. 10. Motivation and emotional behaviour Principal outlet for effects of limbic system Fear and rage Reward and punishment areas
  11. 11. Regulation of body temperature Heat gain Heat loss Anterior hypothalamus (exposure to heat) Posterior hypothalamus (exposure to cold) Cutaneous vasodilatation Sweating, hyperventilation heat production Cutaneous vasoconstriction Release of CAs, TSH activity, hunger Shivering
  12. 12. Regulation of food intake Lateral feeding centre Food intake Ventromedial satiety centre Increase in glucose
  13. 13. Regulation of water balance
  14. 14. Hyperosmolarity Hypovolemia Angiotensin II Subfornical organ Osmoreceptors (supraoptic) Thirst + ADH Increased water intake Decreased urinary volume Osmolarity restored Blood volume restored Regulation of water balance Preoptic area
  15. 15. Disorders/syndromes Etiology: infection, vascular, tumors, compression. • Narcolepsy: sleep disorder • Endocrine: diabetes insipidus, sexual disorders. • Lesion of VM satiety centre: obesity. • Lesion of lateral feeding centre: emaciation. • Temperature regulation.
  16. 16. Hypothalamus: summary • Small area, many nuclei, diverse functions. • Regulates cyclic phenomena: sleep-wake cycle. • Controls autonomic functions. • Neuro-endocrine integration. • Regulates food and water intake. • Regulates body temperature. • Regulation of many functions: homeostasis. • Disordered function: infection, tumors, compression, vascular

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