sensory system

Eye, Ear, Tongue and Nose

numerous photoreceptors situated in the eyes

the outer sclera and transparent cornea middle layer contains the ciliary muscle and iris and inner retinal layer. The lens, ciliary muscles play a role in accommodation which is eye muscle movements made to fine tune focus

transparent layer of the eye, covers the iris and helps in focusing light that enters the eye

tough fibrous outer white layer that protects the eye

lies in the centre of the iris and serves as an entrance for light, its size alternates based on the brightness of one’s surroundings

blood vessel rich region of the eye that lies under the sclera, prevents lights scattering in the eyeball

muscles that hold the lens upright and control its shape

controls the amount of light that enters the eye

focuses light on the retina

neural tissue situated in the back of the eyes, seen as the extension of the brain

maintains pressure of the eye and also transmits light

transmits light and supports the lens

part of the retina that contains the cones (photoreceptors), responsible for high resolution color vision

lays on the center of the retina and it has the greatest visual acuity

2nd cranial nerve located at the back of the eye, transmits visual information from the retina to the vision centres of the brain

rods and cones

dim light

bright light

proteins that change shape when they absorb light, they consist of different variants of opsin in combination with a light absorbing substance derived from vitamin A

rhodopsin photopsins

opsin alter its shape thus converting light energy to electrical impulses

from the rods and cones to the bipolar cells then to the ganglion cells

the axons of the ganglion cells