The Mammalian Eye

Question 1

Sclera

Answer 1

Fibrous layer that protects the eyeball and allows for attachment of external muscles

Question 2

Choroid

Answer 2

Vascular pigmented layer which absorbs light and prevent internal reflection

Question 3

Retina

Answer 3

Photoreceptors layer containing rods and cones

Question 4

Fovea

Answer 4

Region of retina only containing only cones with lots of photoreceptors

Question 5

Optic nerve

Answer 5

Transmits impulses to the brain

Question 6

Blind spot

Answer 6

Region of retina lacking both rods and cones

Question 7

Vitreous humour

Answer 7

Jelly like fluid in the chamber of the eye that maintains the shape of the eyeball

Question 8

Ciliary body

Answer 8

Contains circular muscle that alter the shape of the lens during focusing

Question 9

Iris

Answer 9

Controls the size of the pupil

Question 10

Pupil

Answer 10

Circular opening for directing light to the lens

Question 11

Cornea

Answer 11

Transparent portion of sclera across which the greatest refraction of light occurs

Question 12

Conjunctiva

Answer 12

Membrane that lines the eyelids and protects the cornea

Question 13

Aqueous humour

Answer 13

Watery fluid that fills the anterior chamber of the eye

Question 14

Suspensory ligaments

Answer 14

Attach the lens to the ciliary body

Question 15

Explain how we see (4)

Answer 15

1.light is focused onto retina by the lens 2. Light is absorbed by pigments in the photoreceptors 3. Causes sim of the sodium ion channels to open (generator potential) 4. If threshold is reached,-action potential- bipolar neurone-optic nerve-brain

Question 16

Rods

Answer 16

Monochromatic- one pigment so b+w
More sensitive to low light
Low visual acuity 
Mostly in the peripheral part of the retina 
Many rods share a single bipolar neurone

Question 17

Cones

Answer 17

Trichromatic- red/blue/green
Less sensitive to low light
Higher visual acuity
Each cone has its own bipolar neurone