Physiological and structural change in retina on response to light
- Rod and cone cells have cGMP – gated Na+ channel in outer membrane and non-gated K+ in inner membrane.
- cGMP gated Na+ channel open in absence of light.
- In light, photoreceptors are hyperpolarized due to lower concentration of cGMP causing closure of cGMP- gated Na+
- In darkness, photoreceptors are depolarized due to increased cGMP concentration.
- Rods are responsible for night vision and cones for light vision.
During varying amount of light, rods and cones function in isolation and in tandem