The Human Eye Flashcards

All 6 cards in this deck

What is the function of the cornea?

A transparent layer at the front of the eye that refracts (bends) light to start focusing it on the retina.

What is the function of the retina?

Contains the light receptor cells (rods and cones); light is focused on it and impulses are sent to the brain along the optic nerve.

What happens in the iris reflex in bright light?

e.g. walking outside into bright sunshine

1. Receptors in the retina detect the bright light.
2. Circular muscles of the iris contract and radial muscles relax.
3. The pupil gets smaller, so less light enters and the retina is protected.

How does the eye focus on a near object (accommodation)?

e.g. looking down at a book

1. Ciliary muscles contract.
2. Suspensory ligaments slacken.
3. The lens becomes thicker/more curved, so light is bent more and focuses on the retina.

What is the difference between rod cells and cone cells in the retina?

Rods work in dim light but do not detect colour; cones detect colour but need bright light.

True or false? The lens does most of the refraction of light entering the eye.

False. The cornea does most of the refraction; the lens fine-tunes the focus.