Choose the correct statement.
Nociceptors respond to changes in pressure.
Meissner's corpuscles are thermoreceptors.
Photoreceptors in the human eye are depolarized during darkness and become hyperpolarized in response to the light stimulus.
Receptors do not produce graded potentials.
As we learnt in
Blind Spot -
The optic nerves leave the eye and the retinal blood vessels enter it at a point medial to and slightly above the posterior pole of the eye ball.
- wherein
Photoreceptor cells are not present in that region and hence it is called the blind spot.
Visual cortex -
the photosensitive compounds (photopigments) in the human eyes is composed of opsin (a protein) and retinal (an aldehyde of vitamin A). Light induces dissociation of the retinal from opsin resulting in changes in the structure of the opsin. This causes membrane permeability changes.
- wherein
As a result, potential differences are generated in the photoreceptor cells. This produces a signal that generates action potentials in the ganglion cells through the bipolar cells. These action potentials (impulses) are transmitted by the optic nerves to the visual cortex area of the brain, where the neural impulses are analysed and the image formed on the retina is recognised based on earlier memory and experience.
Option 1)
Nociceptors respond to changes in pressure.
This option is incorrect
Option 2)
Meissner's corpuscles are thermoreceptors.
This option is incorrect
Option 3)
Photoreceptors in the human eye are depolarized during darkness and become hyperpolarized in response to the light stimulus.
This option is correct
Option 4)
Receptors do not produce graded potentials.
This option is incorrect