The Eye Flashcards by Ischia Middleton

effector

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

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receptor cell

a cell that senses a stimulus and transmits the message along

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stimulus

a detectable change in the environment

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response

a change brought about following a stimulus

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reflex

involuntary and almost immediate response to a stimulus

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neurone

(nerve cells)

specialised cells which transmits information through nerve impulses

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nerve

(nerve cell = a single neuron)

a bundle of several neurones

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nerve impulses

electrical signal (current) that travels along a neurone

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label this eye

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label this structure of an eye

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conjunctiva

= layer covering the cornea and sclera

helps to lubricate the eye

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cornea

= clear covering of eye

helps to refract and focus on light

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lens

= transparent structure behind pupil

refracts and focuses on light

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pupils

= hole in centre of iris

controls amount of light entering eye

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iris

= pigmented tissue, sphincter

controls amount of light entering eye

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suspenory ligaments

= ligaments connecting ciliary muscle and lens

involved in controlling accomodation (focusing)

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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