The Eye Flashcards

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1
Q

effector

A

an organ (muscle or gland) that brings about a response

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2
Q

receptor cell

A

a cell that senses a stimulus and transmits the message along

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3
Q

stimulus

A

a detectable change in the environment

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4
Q

response

A

a change brought about following a stimulus

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5
Q

reflex

A

involuntary and almost immediate response to a stimulus

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6
Q

neurone

A

(nerve cells)

specialised cells which transmits information through nerve impulses

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7
Q

nerve

A

(nerve cell = a single neuron)

a bundle of several neurones

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8
Q

nerve impulses

A

electrical signal (current) that travels along a neurone

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9
Q

label this eye

A
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10
Q

label this structure of an eye

A
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11
Q

conjunctiva

A

= layer covering the cornea and sclera

helps to lubricate the eye

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12
Q

cornea

A

= clear covering of eye

helps to refract and focus on light

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13
Q

lens

A

= transparent structure behind pupil

refracts and focuses on light

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14
Q

pupils

A

= hole in centre of iris

controls amount of light entering eye

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15
Q

iris

A

= pigmented tissue, sphincter

controls amount of light entering eye

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16
Q

suspenory ligaments

A

= ligaments connecting ciliary muscle and lens

involved in controlling accomodation (focusing)

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17
Q

ciliary muscle

A

= ring of muscle connected to lens via suspensory ligaments

controls accomodation (focusing)

18
Q

retina

A

= inner layer of eye containing rods + cone

responds to light stimulus

19
Q

optic nerve

A

= sensory nerve (part of CNS)

carries nerve impulses from retina to brain

20
Q

in the pupil reflex, which is the:

receptor

sensory nerve

effector

A

receptor = retina

sensory nerve = optic nerve

effector = muscles in the iris

21
Q

label this diagram of an eye

A
22
Q

what happens to the pupil reflex in dim light

A

radial muscles contract

circular muscles relax

pupil dilates

23
Q

what happens to the pupil reflex in bright light?

A

radial muscles relax

circular muscles contract

pupil constricts

24
Q

in the dark a … action occurs: the … gets larger so that more …can enter the eye and you can see

the oppotite happens in bright light: the … gets smaller and this stops too much … entering the eye and … it

the changes in the … are controlled by muscles in the …

when the pupil contracts (in … light), the … muscles contracted and the … muscles are relaxed

when the pupil dilates (in … light), the … muscles are contracted and the … muscles are relaxed

A

in the dark a reflex action occurs: the pupils gets larger so that more light can enter the eye and you can see

the oppotite happens in bright light: the pupils gets smaller and this stops too much light entering the eye and damaging it

the changes in the pupil are controlled by muscles in the iris

when the pupil contracts (in bright light), the circular muscles contracted and the radial muscles are relaxed

when the pupil dilates (in dim light), the radial muscles are contracted and the circular muscles are relaxed

25
Q

label this struture of the retina diagram

A
26
Q

what are the two photoreceptors?

A

rods

cones

27
Q

what are rods sensitive to?

A

dim light vision

28
Q

what are cones sensitive to?

A

colour vision: blue, red, green

29
Q

what is monochromacy

A

total colour blindness

30
Q

what is anomalous trichomacy

A

red-green blindness

31
Q

what is night blindness

A

when rods don’t respond to light

32
Q

our retinas our covered with light sensitive cells called … and …

the … detect the intensity of light and allows us to see if things are bright or dark

the … detect colour. when there is little light, the … do not work so we find it difficult to tell what … things are

there are … types of cone cells in the retina

each type is sensitive to a different colour of light: …, … or …

A

our retinas our covered with light sensitive cells called rods and cones

the rods detect the intensity of light and allows us to see if things are bright or dark

the cones detect colour. when there is little light, the cones do not work so we find it difficult to tell what colour things are

there are three types of cone cells in the retina

each type is sensitive to a different colour of light: red , blue, or green

33
Q

accommodation

A

the reflex that makes the eye focus on an object by changing the shape of its lens

34
Q

light reflected from an object is … (bent) by the … and the … forming an upside down image on the …

the … interprets this image so that it appears upright to us

the lens … is adjustable and so can bend light more or less, thus allowing the eye to … on an object at different distances

A

light reflected from an object is refracted (bent) by the cornea and the lens forming an upside down image on the retina

the brain interprets this image so that it appears upright to us

the lens shape is adjustable and so can bend light more or less, thus allowing the eye to focus on an object at different distances

35
Q

describe how distant objects appear when focusing on a distant object and why

A

light rays from a distant object arrive at the eye nearly parallael

when the eye focuses on a distant object the lens is flatter so that the light rays retract less

36
Q

describe how nearby objects appear when focusing on a distant object and why

A

light rays from a nearby object come into the eye at an angle

if they are not refrcted enough the object will look blurry

37
Q

describe how nearby objects appear when focusing on a nearby object and why

A

to focus on a nearby object the lens becomes rounder (more convex) so that light rats are refracted more

38
Q

describe how distant object appear when focusing ona nearby object and why

A

the light rays from a distant object are refracted too much so that the object will look blurry

39
Q

label this mechanism of accommodation diagram for focusing on a distant object

A
40
Q

label this mechanism of accommodation diagram for focusing on a nearby object

A
41
Q

give a reflex action that occurs in dim light

A

we can adjust our vision to see in dim light