Get premium membership and access revision papers with marking schemes, video lessons and live classes.

Processing. Please wait.

Describe the functions of the various parts of the human eye

Answer Text:
(i) Sclerotic/ sclera- it is made up of collagen fibres thus protects the eye and also maintains the shape of eyeball.
(ii) Cornea- allows light to enter the eye also it
refracts light towards retina.
(iii) Conjunctiva- protects cornea and the entire eyeball
(iv) Eyelids- protects cornea from mechanical or chemical damage/ protect eye from entry of foreign particles also protects retina from bright light
(v) Choroids – ( contain black pigment which) prevents reflection of light within the eye/ absorbed light. It also nourishes the eye or retina by supplying oxygen and removing carbon (IV) oxide.
(vi) Ciliary muscles- alter shape of lens during accommodation. Also the ciliary body produces aqueous humour.
(vii) Suspensory ligaments- adjust shape of lens during accommodation.
(viii) Lens – refracts light rays or focuses light on retina
(ix) Vitreous humour or aqueous humour – nourish cornea and the lens, refracts light
(x) Iris – it is pigmented thus gives the eye it colour. It absorbs light and also controls amount of light entering the eye by adjusting the size of pupil.
(xi) Pupil- light enters the eye through pupil
(xii) Retina – has photoreceptor cells (i.e rods and cones) which cause image formation as they generate impulses.
(xiii) Forea/yellow spot- visual acuity most sensitive part of retina with only cones.
(xiv) Blind spot- a point where nerve fibre emerges from the optic nerve/ where the optic nerve leaves the eye.
(xv) Optic nerve- transmit impulses to brain for interpretation.