bio question: Explain why photoreceptors of the eye are organised in certain areas of the retina. (1 Viewer)

[stressedadfff]

does anyone know

 

[Eagle Mum]

There are two types of photoreceptors - rods & cones.

Vision in daylight is predominantly cone-mediated which is responsible for colour detection. Rods mediate vision in low light settings. The total number of rods far exceeds the number of cones throughout most of the retina except in the fovea, a highly specialized region of the central retina.

In the fovea, cone density increases almost 200-fold and at its center, photoreceptor density is the highest in the retina. The increased density of cones in the fovea is accompanied by decreased density of rods with the central foveola being totally rod-free.

The high density of cone receptors and the one-to-one connection with nerve ganglion cells in the fovea enable high visual acuity such as for reading. As cone density declines away from the fovea, acuity is sharply reduced. On the other hand, since rod density is higher away from the fovea, it is easier to see a dim object (such as a faint star) by looking away from it, so that the stimulus falls on the region of the retina away from the fovea.

So, cones enable central, focused, detailed sight and rods enable peripheral sweeping scans.

 

[stressedadfff]

THANK YOU HEAPSSSS