Choose the correct statement

Options

A. Nociceptors respond to changes in pressure
B. Meissner's corpuscles are thermoreceptors
C. Photoreceptors in the human eye are depolarised during darkness and become hyperpolarised in response to the light stimulus
D. Receptors do not produce graded potentials

Answer

C

Explanation

The photosensitive compounds (rhodopsin) in the human eye is composed of opsin (a protein) and retinal (an aldehyde of vitamin-A, i.e. retinol). They, are present in the rod cells (photoreceptors). Light induces dissociation of retinal from opsin thus changes the structure of opsin. This creates potential difference in the photoreceptors and they become hyperpolarised.
However, during darkness rhodopsin is resynthesised from opsin and retinal to restore the dark vision and photoreceptors are depolarised.