Equilibrium

• 2 types of equilibrium

  • static equilibrium
  • dynamic equilibrium
• Static equilibrium is the maintenance of body position relative to the force of gravity. It is stimulated by tilting head, elevator or a car speeding or slowing down
• Dynamic equilibrium is the maintenance of body position in response to rotational speeding or slowing down (spinning)
• Static equilibrium is sensed by the vestibule of the inner ear. It contains hair cells imbedded in otolithic membrane
• Mechanism of sensing static equilibrium

  • gravity pulls on otolithic membrane
  • otolithic membrane bends hairs
  • triggers nerve impulse that travels to cerebellum and motor cortex
• Dynamic equilibrium is sensed by semicircular canals of the inner ear. They contain hair cells imbedded in jelly like cupula with endolymph around it.
• Mechanism of sensing dynamic equilibrium

  • when head turns: hair cells move
  • endolymph lags and bends hair cells
  • triggers nerve impulse that travels to cerebellum and motor cortex