Transcript Sense and Control

Sense and Control
Year 9 Science
Sight
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Eyes provide what many would regard
as the most important of all our
senses—sight.
The eye contains several parts similar
to a camera. Both perform similar
tasks—focusing on and capturing
images.
Eyes and Cameras
The Eye
Eye Protection
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Eyebrows and eyelashes help keep dust
out.
Tear ducts produce tears to flush out any
foreign particles.
Eyes are set back in depressions in our skulls
called orbits to give them some protection
from being knocked.
Protective eyewear should always be used
in science classes when handling or heating
chemicals that could spit or spill from their
containers.
Eye Protection
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Protective eyewear should always be used
in science classes when handling or heating
chemicals that could spit or spill from their
containers.
If a foreign substance does get into your
eye, flush it immediately with water while
trying to keep your eye open to allow water
to contact the affected area. An eyewash
bottle should be available for this purpose.
Why two eyes?
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Two eyes allow us to judge distance
more accurately.
Each eye sees a slightly different view
and the brain combines the two
images to create a 3D view.
This is known as binocular vision.
Colour vision
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The retina contains specialised cells called
rods and cones.
Rods are more sensitive and only respond
to light and dark.
Cones need more light to be active and
come in three types; red, blue and green.
A scanning electron microscope
photograph of rods and cones
Colour Blindness
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People who lack one or more types
of cones cannot tell the difference
between colours, or are colour
blind.
1 in 15 males is colour blind
1 in 1000 females is colour blind
Ishihara Test for Colour Blindness
Ishihara Test for Colour Blindness
The individual with normal colour vision will see a 5
revealed in the dot pattern.
An individual with Red/Green (the most common)
colour blindness will see a 2 revealed in the dots.
Animal Eyes
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The eyes of different animals are highly
specialised.
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rabbit’s eyes are positioned on the sides of its
head so that it can see most of its surroundings
without moving its head and attracting attention.
The eagle has excellent eyesight and can detect a
rabbit from three kilometres away
Animal Eyes
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Owls have both eyes at the front to allow better
judgement of distance when swooping on prey.
Insects may have multiple lenses to provide an
all-round view.
Spiders have four, six or eight eyes, and
scorpions have between six and twelve.
Eye Defects
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In some people the lens has become less
elastic and is unable to focus images at
exactly the right position in the eye.
Myopia (short-sighted)
Hyperopia (long-sighted)
Presbyopia – a person looses the ability
to focus at short distances due to age.
Eye Defects
Hearing
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Parts of the human ear
Hearing Sound Waves
The human ear can detect sound
waves.
The sound waves cause small but rapid
pressure changes to anything they
strike.
The ear turns these pressure changes
into electrical impulses, which are then
sent by nerves to the brain for
interpretation.
The Ear
Describe the structure and function of
the following parts of the ear and
Indicate the section of the ear that each
part fits into.
 Eardrum
 Hammer,
anvil and stirrup.
 Oval window
 Cochlea
 Auditory nerves
 Semicircular canals
Two Ears
Two Ears
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Two ears help us determine the
direction of a sound.
If a sound reaches both ears at the
same time, our brain tells us that the
source of the sound is directly in front
of, behind or above us.
If a sound reaches the left ear before
the right ear, the brain tells us that the
source of the sound is to our left.
Why do we have two ears?
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Think of some of
the adaptations
some animals
have with their
different ear
shapes and sizes.
Ear Problems
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Prolonged exposure to loud sounds
can flatten the hairs of the cochlea.
As the hairs recover so does your
hearing, but not completely.
Deafness can be cause by a build up
of wax, jamming of the ossicles
together, birth defects, noise and
infections
Hearing Problems
Explain the cause and effects of
flattening of the hairs of the
cochlea.
Explain the cause and effects of a rip
to the eardrum.
Ear Protection
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List ways to minimise hearing
problems.
Hearing Technologies.
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Hearing aids work to amplify
sounds and transmitting them
to the auditory canal.
Hearing Technologies.
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Cochlea implants replace the
inner ear. A microphone sends
information to a speech
processor which sorts out
information and sends it to a
receiver that stimulates the
cochlea. Messages are then sent
to the brain.
Touch
The skin is an organ
containing millions of
nerve endings that
transmit information
about touch, pain and
temperature to the brain.
The Skin
The skin is bodies protective outer
boundary. It is the largest organ of your
body. It has many functions including:
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Protecting the body from germs
Helps control your body temperature
Stops you from dehydrating
Forms vitamin D in sunlight
Releases water and other waste
Detects pain, pressure, heat and
movement.
Skin Conditions
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A wart is a raised rough, dry lump on
the surface of the skin.
A mole is a raised dark coloured
growth of the skin.
Freckles are dark spots of melanin.
Pimples are caused when the
sebaceous gland secretes to much or
into a hair follicle or the follicle is
blocked.
Skin Cancers
Basal cell carcinomas –
usually are red flaky lumps
on the skin.
Squamous cell carcinomas
– red scaly sores that
spread.
Melanomas – the most
deadly skin cancer that
spreads rapidly.
Where is the skin most sensitive?
Method
1 Attach two toothpicks to a ruler as shown.
2 Make sure your partner cannot see while you touch
both toothpick points to a region of skin. Ask your
partner how many points they feel.
3 Move the toothpicks closer to each other and test
again. Progressively move the toothpicks closer
together until only one can be felt.
4 Test other regions of the skin the same way. Some
possible areas to try are the back of the hand, palm,
inside forearm, back of forearm, leg, foot, back of
neck.
5 Swap jobs and have your partner test you.
Where is the skin most sensitive?
Where is the skin most sensitive?
Distance between two points
in mm.
Part of the skin Your partner
You
Palm
Knee
Cheek
Forehead
Back of hand
Sense of smell
Smell
Smell is detected when tiny particles
enter the nose and dissolve in its
moist lining.
The dissolved substances trigger
olfactory nerves, which send
messages to the brain.
Smell fatigue
Aim To investigate the phenomenon
of smell fatigue.
Equipment
A safe, strong-smelling substance, a
watch, a small container.
Smell Fatigue
Method
1 Obtain a sample of a safe, strong-smelling
substance in a container that can be sealed.
2 Carefully take a small whiff of the substance.
Do not breathe in too deeply.
3 Re-seal the container and wait 30 seconds
before taking a similar whiff. Rate the
strength of the smell from 0 (no smell) to 5
(the strength of your first smell).
4 Continue to take a whiff every 30 seconds,
giving the strength of the smell a rating each
time until you have about six ratings.
Smell fatigue
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Describe what happens to the
strength of what you smell after
several whiffs.
Construct a graph to display your
ratings.
Taste
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The tongue is covered bumps,
called papillae. The taste buds are
embedded between the papillae.
Humans can detect five taste
sensations: sweet, sour, salty, bitter
and umami (savoury).
Taste Bud
Taste
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Saliva in our mouths dissolves
samples of food so taste buds can
detect taste and send messages to
the brain.
Flavour
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When we eat, our senses of smell
and taste work together to detect
flavour. As much as 80% of what we
perceive as flavour is actually smell.
Flavour is largely the smell of gases
emitted from food that has just
been taken out of your mouth.
Brand name versus no name
Aim To compare the taste of various products
and investigate the role of smell in the
taste process
Equipment
Samples of various edible substances;
blindfold; new plastic cups
‘brand name’ chocolate, ‘no name’ chocolate,
brand name lemonade, ‘no name’
lemonade, brand name biscuits, ‘no name’
biscuits
Brand name versus no name
Method
1 Work with a partner or group and
blindfold one person.
2 Give the blindfolded person a taste of
a ‘brand name’ and ‘no name’ pair of
foods, and record their observations.
3 Repeat for the other food items.
4 Repeat the tests, but have the tester
pinch his or her nose shut while
tasting.
Responding
Through our senses we constantly
receive information. Responding to
this information allows us to react,
enhancing our chances of survival.
Sense Receptors
Stimulus
Location of receptor
Heat or cold
Thermoreceptors in the skin
Water levels in the blood Osmoreceptors in the brain and
arteries
Pressure and touch
Mechanoreceptors in the skin
Sound
Cochlear cells in inner ear
Light
Photoreceptors in retina of eye
Chemicals
Chemoreceptors on the tongue
and nose
Gravity
Semi circular canals in the ears
Stimulus-Response Model
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A stimulus is something acting on
an receptor that causes a change in
the organism.
A message is then sent to a
effector, which is anything that
causes a response (eg a gland or
muscle).
Feedback
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Information on the stimulus-response so the
organism can adjust any further responses.
Coordination
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The total response of an organism to
stimulus, possibly involving several parts of
the body.
The Nervous System
The nervous system has two parts:
• the central nervous system
• the peripheral nervous system.
The central nervous system (CNS) is
made up of the brain and spinal cord.
They act as a control centre, receiving
messages from all parts of the body,
examining the data received, and then
sending out messages to tell parts of the
body what to do.
The Nervous System
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The peripheral nervous system
(PNS) is made up of sensory
receptors and nerves. These
continuously inform the CNS of
changing conditions, and transmit
the decisions made by the CNS back
to effector organs. Messages are
passed through the system by
nerve cells called neurons.
Neurons
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Specialised cells that transmits and receives
messages in the form of electrical impulses.
Sensory Neurons
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Sensory neurons, have specialised
endings sensitive only to stimuli
such as heat and light. These form
part of the body’s larger sense
organs (eyes, ears etc.), which
function by collecting different
energy forms. The sensory neuron
then converts this energy into an
electrical impulse.
Other Neurons
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The connecting neurons or
interneurons, transfer these
electrical messages within the CNS.
A third type, motor neurons,
transfer messages from the CNS to
effector organs such as muscles.
The Nervous System
Use page 241 of your textbook to
answer these questions.
1. What is the CNS?
2. What is the PNS?
3. What are neurons?
4. Name the three types of neurons
and describe their functions.
Synapse
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There are small gaps between the neurons
known as synapses.
Messages move across the gap by chemical
compounds called neurotransmitters.
Drugs like cocaine and ecstasy increase the
production of neurotransmitters resulting in a
heightened state of alert.
Synapse
Reflex arc
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A stimulus is detected by the
receptors and is sent along a sensory
neuron to the spinal cord.
The message then is carried by a
motor nerve to the effector, without
involving the brain.
Reflex Arc
The Endocrine System
Chemical Control
Hormones
 The endocrine system uses chemical
messages called hormones to transfer
information around the body. These
hormones are responsible for controlling
many changes that occur in our bodies
such as growth, reproduction water
balance and the rate of chemical
reactions in cells.
Hormones
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Hormones travel to all parts of the body
but only cells targeted respond to the
hormone. A hormone has a specific
shape that fits chemically on the
targeted cells membrane.
Why hormones?
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The circulation of hormones takes time
but once the hormone has reached the
cell the effects are long lasting
Control of blood glucose levels
The Brain
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The brain is made up of around
25,000 billion neurons which are
connected to as many as 1000
others.
This huge number of neurons form
specific circuits
Structure of the brain
The brain is made up of three main parts.
 The cerebellum controls complex
muscular movements like cycling walking
and running.
 The medulla controls vital involuntary
functions like heartbeat and breathing.
 The cerebrum makes up 90% of the
brains volume and is divided into the left
and right hemispheres.
The Human Brain
Right Hemisphere Characteristics
Intuitive
•Responds to demonstrated instructions
•Problem solves with hunches, looking for patterns and configurations
•Looks at similarities
•Is fluid and spontaneous
•Prefers elusive, uncertain information
•Prefers drawing and manipulating objects
•Prefers open ended questions
•Free with feelings
•Prefers collegial authority structures
Simultaneous
•Is a lumper: connectedness important
•Is analogic, sees correspondences, resemblances
Draws on unbounded qualitative patterns that are not organized into sequences, but that
cluster around images
Left brain characteristics
Rational
•Responds to verbal instructions
•Problem solves by logically and sequentially looking at the parts of things
•Looks at differences
•Is planned and structured
•Prefers established, certain information
•Prefers talking and writing
•Prefers multiple choice tests
•Controls feelings
•Prefers ranked authority structures
Sequential
•Is a splitter: distinction important
•Is logical, sees cause and effect
Draws on previously accumulated, organized information
The Pituitary Gland
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The pituitary gland plays an important
role in controlling growth.
It not only releases hormones but also
instructs other cells to release their
hormones.
The gland receives instructions from
the hypothalamus in the brain linking
the endocrine and nervous systems.
Dissection Rules
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Stay safe
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Follow all directions
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Always cut away from yourself
and others.
Leave the brain on the tray at all
times
 Clean up when instructed
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