Hypothalamus

• Hypothalamus


  the hypothalamus caps the brain stem

  merging into the midbrain inferiorly, the hypothalamus extends from the optic chiasma (crossover point of the optic nerves) to the posterior margin of the mammillary bodies

  
• Mammillary Bodies


  the mamillary bodies r paired nuclei that bulge ventrally from the hypothalamus

  = relay stations in the olfactory pathways

  
• Infundibulum


  between the optic chiasma + mammillary bodies in the infundibulum, a stalk of hypothalamic tissue that connects the pituitary gland to the base of the hypothalamus
• Controlling the Autonomic Nervous System

  ANS = system of peripheral nerves that regulate cardiac + smooth muscle + scretion by the glands

  the hypothalamus regulastes ANS activity by controlling the activity of centres in the brain stem + spinal cord

  in this role, the hypothalamus influences blood pressure, rate + force of heartbeat + digestive tract motility
• Regulating Body Temperature


  the body's thermostat is in the hypothalamus

  hypothalamic neurons monitor blood temp + receive input from other thermoreceptors in the brain + body periphery

  accordingly, the hypothalamus initates cooling/sweating or heat-generationg actions like shivering to maintain a realtively constant body temp
• Regulating Water Balance & Thirst

  when body fluids become concentrated, hypothalamic neurons - osmoreceptors r activated

  osmoreceptors excite hypothalamic nuclei that tirgger the release of ADH from the posterior pituitary

  = causes the kidneys to retain water

  the same condition also stimulate hypothalamic neurons in the thirst centre, causing us to feel thirsty + drink more fluids
• Controlling Endocrine System Function

  the hypothalamus acts as the helmsman of the endocrine system in 2 important ways

  firtst, its releasing + inhibiting hormones control the secretion of hormones by the anterior pituitary gland

  second, its nuclei produce the hormones ADH + oxytocin