Question

What are rods and what are cones? What are their functions?

Answer 1

Rod cells - These are a type of photoreceptor cells present in the eye. Generally, these type of cells are concentrated at the outer edges of the retina and are also responsible for pheripheral vision. They are the cells which are solely responsible for vision in the night. Rod cells does not contain any type of pigment, so they are most active at the time of darkness. Also they are more sensitive than cone cells.

Cone cells - These are also a type of photoreceptor cells present in the eye, which are responsible for the vision in bright light compared to rod cells. These are the cells which will also produce color vision due the presence of colored pigments. As, the humam can perceive light only in visible area of the spectrum, the cones are of three types depending upon presence of pigement and wavelength namely, S-cones (short wavelength), M-cones (Medium-wavelength) and L-cones (Long wavelength). They are less sensitive to light as compared to rod cell.

Cone cells are present approximately 7 million in number compared to 10 million rod cellsin human eye.