.5 Receptors and Eyes

• specificity- involves energy an change >receptors only respond to specific stimuli e.g light , temperature, pressure
• a receptor that responds to light will not respond to temperature or pressure
• The Pacinian Corpuscle:

  mechanoreceptor in the skin respond to changes in pressure to establish a generator potential
• Resting potential-

  • consists of concentric rings of connective tissue surrounding a sensory neurone
  • at resting state the charge inside is more negative than outsidemore Na+ ions outside
  • potential difference (difference in charge)
• Stimulation-

  • pressure is applied (lamallae and SN membrane are distorted), the rings of the connective tissue apply pressure to the sensory neurone
  • it has stretch mediated Na+ channels, these restrict movement of Na+ ions
  • applied pressure casues these to open, Na+ move in via diffusion, action potential is created
• generator potential-

  • connect with sensory neurones , the receptor creates a generator potential in the sensory neurone
  • e.g pacinian corpsule
• GP-

  • Na+ ions flood into the sensory neurone through the channels
  • more Na+ inside
  • charge more negative outside, potential difference has changed
  • potential established
• how it produces a generator potential: pressure increases which changes the stretch mediated Na+ channels, they open and Na+ flows in , depolarisation leads to generator potential