Chapter 14 The Human Eye Structure and Function of the Eye (Concept Map) 17 April 2017 Biology Matters textbook page 281 Concept Map

Vertical Section of The Human Eye Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 2

Vertical Section of The Human Eye suspensory ligament Attaches lens to ciliary body Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 3

Vertical Section of The Human Eye suspensory ligament iris Controls amount of light entering the eye Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 4

Vertical Section of The Human Eye suspensory ligament iris aqueous humour Refracts light rays; keeps eyeball firm Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 5

Vertical Section of The Human Eye suspensory ligament iris aqueous humour pupil Allows light to enter the eye Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 6

Vertical Section of The Human Eye suspensory ligament iris aqueous humour pupil cornea Refracts light rays into pupil Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 7

Vertical Section of The Human Eye suspensory ligament iris aqueous humour pupil cornea lens Focuses light rays onto retina Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 8

Vertical Section of The Human Eye suspensory ligament iris aqueous humour pupil cornea lens ciliary body Contains ciliary muscles which control curvature or thickness of the lens Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 9

Vertical Section of The Human Eye suspensory ligament iris aqueous humour pupil cornea lens ciliary body viterous humour Refracts light rays; keeps eyeball firm Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 10

Vertical Section of The Human Eye suspensory ligament rectus muscles Controls movement of eyeball iris aqueous humour pupil cornea lens ciliary body viterous humour Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 11

Vertical Section of The Human Eye suspensory ligament rectus muscles iris sclera aqueous humour Protects against mechanical injury pupil cornea lens ciliary body viterous humour Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 12

Vertical Section of The Human Eye suspensory ligament rectus muscles iris sclera aqueous humour choroid Pigmented black to prevent internal reflection of light; blood vessels bring oxygen and nutrients to the eyeball pupil cornea lens ciliary body viterous humour Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 13

Vertical Section of The Human Eye suspensory ligament rectus muscles iris sclera aqueous humour choroid pupil fovea (yellow spot) cornea Region where images are sharply focused lens ciliary body viterous humour Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 14

Vertical Section of The Human Eye suspensory ligament rectus muscles iris sclera aqueous humour choroid pupil fovea (yellow spot) cornea lens optic nerve Transmit nerve impulses from eye to brain ciliary body viterous humour Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 15

Vertical Section of The Human Eye suspensory ligament rectus muscles iris sclera aqueous humour choroid pupil fovea (yellow spot) cornea lens optic nerve ciliary body blind spot Region over optic nerve; no photoreceptors, so insensitive to light viterous humour Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 16

Vertical Section of The Human Eye suspensory ligament rectus muscles iris sclera aqueous humour choroid pupil fovea (yellow spot) cornea lens optic nerve ciliary body blind spot viterous humour retina Light-sensitive layer containing cones responsible for colour vision in bright light and rods responsible for vision in dim light Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 17 April 2017 17

Vertical Section of The Human Eye Pupil Reflex A reflex action in which the pupil changes size as a result of changes in light intensity. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18

Vertical Section of The Human Eye Pupil Reflex In bright light Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 19

Vertical Section of The Human Eye Pupil Reflex In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 20

Vertical Section of The Human Eye Pupil Reflex In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye In dim light Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 21

Vertical Section of The Human Eye Pupil Reflex In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye In dim light Radial muscles in iris contract . Circular muscles in iris relax. Pupil enlarges, hence more light enters the eye Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 22

Vertical Section of The Human Eye Pupil Reflex Focusing The adjustment of the lens of the eye so that clear images of objects at different distances are formed on the retina. In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye In dim light Radial muscles in iris contract . Circular muscles in iris relax. Pupil enlarges, hence more light enters the eye Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23

Vertical Section of The Human Eye Pupil Reflex Focusing In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye In dim light Radial muscles in iris contract . Circular muscles in iris relax. Pupil enlarges, hence more light enters the eye Distant object (7 metres or more) Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 24

Vertical Section of The Human Eye Pupil Reflex Focusing In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye In dim light Radial muscles in iris contract . Circular muscles in iris relax. Pupil enlarges, hence more light enters the eye Distant object (7 metres or more) Ciliary muscles relax Suspensory ligament become taut Lens becomes thinner and less convex Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 25

Vertical Section of The Human Eye Pupil Reflex Focusing In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye In dim light Radial muscles in iris contract . Circular muscles in iris relax. Pupil enlarges, hence more light enters the eye Distant object (7 metres or more) Ciliary muscles relax Suspensory ligament become taut Lens becomes thinner and less convex Near object Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 26

Vertical Section of The Human Eye Pupil Reflex Focusing In bright light Circular muscles in iris contract. Radial muscles relax. Pupil becomes smaller, hence less light enters the eye In dim light Radial muscles in iris contract . Circular muscles in iris relax. Pupil enlarges, hence more light enters the eye Distant object (7 metres or more) Ciliary muscles relax Suspensory ligament become taut Lens becomes thinner and less convex Near object Ciliary muscles contract Suspensory ligaments slacken Lens becomes thicker and more convex Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 27