chapter 11 sense organs
TRANSCRIPT
8/12/2019 Chapter 11 Sense Organs
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Sense organs
Perception
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The receptorsStimuli are things that affect
our behaviour, e.g. Light,sound, temperature,
gravity, touch, pain and
chemical taste.
Sense organs have receptorsthat detect these stimuli
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The eyeThe eyes receive light then
brings it to focus on theretina.
Cells in the retina detectscolour, and light. The braininterprets the impulses
passed to it by the eyes, thenproduces the pictures wesee.
The eyes are protected by the
eye brows prevent sweatand eyelids prevent dirt andstones from entering the eye.The eye ball is also in asocket that protects it fromknocks.
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Structure of the eye.Sclera- the white of the eye.
Helps the eye to keep itsshape.
Conjunctiva- prevents grit
and other substances from
entering the eye.
Cornea – the transparent part
of the sclera.
Iris - the muscle that controlsthe size of the pupil.
Pupil- allows light to pass
through the eye.
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Structure of the eye.Virteous and aqueous
humour –
the jelly like fluidthat helps the eye keep its
shape. They also bend the
light that enters the eye.
Lens - focus light on theretina.
Suspensory ligaments-
change the shape of the
lens.
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The retinaThe retina is a thin
layer of sensitive
cells that convertlight to electrical
impulses.
The retina sends
impulses via theoptic nerve to the
brain. The optic
nerve pass out of
the eye throughthe blind spot (
the light sensitive
cells are absent).
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The retinaThe light sensitive cells in the
retina are of two kinds.
The cones are sensitive to
colour and are affected by
high intense light.
The rods are sensitive toblack and white.
The fovea is the centre of the
retina. It contains cones
that give really good
details.
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Colour blindnessColour blind persons only see
black, grey and white. This
occurs when the rods and
cones do not work
properly.
Red/green colour blindpersons cannot distinguish
between red and green .
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The pupilThe pupil size gets smaller in
bright light and lager in
dim light.
This reflex action controls the
amount of light entering
the eye.Images formed on the retina
are inverted (upside
down). The brain then turn
them right side up.
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Cause and correction of sight defectsSight defects are made better
by using glasses.
Long sightedness occurs
when near objects cannot
be seen properly. A convex
lens is used to help correctlong sightedness.
Short sightedness occurs
when far objects cannot be
seen properly. A concave
lens is used to correct
short sightedness.
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The earThe ear is used for receiving
sound, detecting gravity andassist in balance.
The outer air collect sound waves
and pass to through the
auditory canal.The ear drum separates the
outer air from the inner ear.
Sound waves cause the ear
drum to vibrate. This vibration
is amplified by three small
bones called ossicles which
pass them to the inner ear.
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The vibrations travel to
the inner air where
they are changed toelectrical impulses by
the COCHLEA. The
impulses are
transported to thebrain by the auditory
nerve.
The auditory centre of
the brain interpret the
impulses as sounds.
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Gravity and BalanceThe semicircular canals
are located in the
inner ear above the
cochlea.
Each movement of the
head cause fluids inthe ear to stimulate
the semicircular
canal to coordinate
which muscle isneeded to keep your
balance.
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The tongueTaste is detected by the taste
buds in the tongue. Thetaste buds detect four
basic taste, sour, sweet,
salt and bitter.
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