The Eye Flashcards
effector
an organ (muscle or gland) that brings about a response
receptor cell
a cell that senses a stimulus and transmits the message along
stimulus
a detectable change in the environment
response
a change brought about following a stimulus
reflex
involuntary and almost immediate response to a stimulus
neurone
(nerve cells)
specialised cells which transmits information through nerve impulses
nerve
(nerve cell = a single neuron)
a bundle of several neurones
nerve impulses
electrical signal (current) that travels along a neurone
label this eye
label this structure of an eye
conjunctiva
= layer covering the cornea and sclera
helps to lubricate the eye
cornea
= clear covering of eye
helps to refract and focus on light
lens
= transparent structure behind pupil
refracts and focuses on light
pupils
= hole in centre of iris
controls amount of light entering eye
iris
= pigmented tissue, sphincter
controls amount of light entering eye
suspenory ligaments
= ligaments connecting ciliary muscle and lens
involved in controlling accomodation (focusing)
ciliary muscle
= ring of muscle connected to lens via suspensory ligaments
controls accomodation (focusing)
retina
= inner layer of eye containing rods + cone
responds to light stimulus
optic nerve
= sensory nerve (part of CNS)
carries nerve impulses from retina to brain
in the pupil reflex, which is the:
receptor
sensory nerve
effector
receptor = retina
sensory nerve = optic nerve
effector = muscles in the iris
label this diagram of an eye
what happens to the pupil reflex in dim light
radial muscles contract
circular muscles relax
pupil dilates
what happens to the pupil reflex in bright light?
radial muscles relax
circular muscles contract
pupil constricts
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
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
label this struture of the retina diagram
what are the two photoreceptors?
rods
cones
what are rods sensitive to?
dim light vision
what are cones sensitive to?
colour vision: blue, red, green
what is monochromacy
total colour blindness
what is anomalous trichomacy
red-green blindness
what is night blindness
when rods don’t respond to light
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 …
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
accommodation
the reflex that makes the eye focus on an object by changing the shape of its lens
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
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
describe how distant objects appear when focusing on a distant object and why
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
describe how nearby objects appear when focusing on a distant object and why
light rays from a nearby object come into the eye at an angle
if they are not refrcted enough the object will look blurry
describe how nearby objects appear when focusing on a nearby object and why
to focus on a nearby object the lens becomes rounder (more convex) so that light rats are refracted more
describe how distant object appear when focusing ona nearby object and why
the light rays from a distant object are refracted too much so that the object will look blurry
label this mechanism of accommodation diagram for focusing on a distant object
label this mechanism of accommodation diagram for focusing on a nearby object
give a reflex action that occurs in dim light
we can adjust our vision to see in dim light
