B1d: The Nervous System

Our bodies have to respond to changes that happen both inside and outside the body. The nervous system plays a major part in this. This item provides the opportunity to collect and analyse primary scientific data when investigating density of nerve endings in different skin areas and secondary data when researching reaction times in races. Theories and ideas can be tested in the investigation of binocular vision. This item develops safe and accurate work skills, along with analysis of ideas. 

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How do animals detect changes in their environment?
The environment is the stimulus. Their sensory neurones carry the information from receptors to the CNS. The CNS sends the information to an effector along a motor neurone. The effector responds accordingly.
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Name the parts of the eye in order from front to back.
Cornea, pupil, iris, lens, ciliary muscle, suspensory ligaments, retina, blind spot and optic nerve.
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Advantage and disadvantage of monocular vision.
Wider field of view but poorer judgement of distance.
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Advantage and disadvantage of binocular vision.
Narrower field of view but better judgement of distance.
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Main problems of vision: short sighted?
Someone with short-sightedness can see near objects clearly, but can't focus properly on distant objects. This is because the lens focuses the sharpest image in front of the retina, instead of on it.
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Main problems of vision: Long sighted?
Someone with long-sightedness can see distant objects clearly, but can't focus properly on near objects. This is because the lens focuses the sharpest image behind the retina, instead of on it.
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Main problems of vision: Red-green colour blindness?
People with colour blindness have a lack of receptors, or defects in them. People with red-green colour blindness, for example, have difficulty distinguishing shades of red and green.
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What does the nervous system consist of and where are they found?
The central nervous system (brain and spinal cord) and peripheral nervous system (outside of the brain and spinal cord)
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Describe the nerve impulse.
The nerve impulse is an electrical signal that is carried by nerve cells called neurones.
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Describe reflex actions.
Reflex actions are fast, automatic and protective responses.
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What type of control are voluntary responses under?
Voluntary responses are under the conscious control of the brain.
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Describe the function of the cornea.
Refracts light.
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Describe the function of the iris.
Controls how much light enters the pupil.
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Describe the function of the lens.
Focuses light on to the retina.
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Describe the function of the retina.
Contains light receptors, some sensitive to light of different colours.
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Describe the function of the optic nerve.
Carries impulses to the brain.
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Describe the pathway of light.
The light is refracted by the cornea and lens, so that it is brought to a focus on the retina.
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Explain how the eye focuses on distant objects.
The ciliary muscle relaxes, which allows the suspensory muscles to pull tight. This pulls the lens into a less rounded shape so light is refracted less.
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Explain how the eye focuses on close objects.
The ciliary muscle contracts, which slackens the suspensory muscle. The lens becomes a more rounded shape, so light is refracted more.
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Talk about binocular vision, and how it allows you to judge distances.
When you look at an object, your brain compares the images seen by each eye. The more similarities between each eye, the further away the object. This allows us to judge distances well, but gives us a narrow field of vision.
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How is long-sighted vision caused?
The lens is the wrong shape and doesn't refract the light enough, or the eyeball is too short. The images of near objects are brought into focus behind the retina.
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How is short-sighted vision caused?
The lens is the wrong shape and refracts too much light, or the eyeball is too long. The images of distant objects are brought into focus in front of the retina.
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How is short-sighted vision fixed?
Concave lens, or corneal laser surgery.
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How is long-sighted vision fixed?
Convex lens, or corneal laser surgery.
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Explain a cause of red-green colour blindness.
Lack of specialised cone cells in the retina.
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Where to nerve impulses pass along?
The axon of a neurone.
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Describe a reflex arc.
Stimulus - Receptor - Sensory neurone - Central Nervous system - Motor neurone - Effector - Response.
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What is the path taken by a spinal reflex?
Receptor - Sensory neurone - Relay neurone - Motor neurone - Effector.
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How are neurones adapted to their function?
They have dendrites to connect with other neurones and a sheath along the axon that acts as an electrical insulator and long to speed up the electrical impulse.
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Why does being a long neurone speed up electrical impulses?
Because transferring to another neurone slows the impulse down, so a few longer ones are better than lots of short ones.
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Name the parts of a motor neurone in order from front to back.
Dendrites, Cell body, Nucleus, Axon, Insulating sheath and synapse.
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What is a synapse?
The connection between two neurones.
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Describe what happens at a synapse.
An electrical impulse triggers the release of transmitter chemicals, which diffuse across the gap. These chemicals bind to receptor molecules in the membrane of the next cell. This sets off a new electrical impulse.
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Other cards in this set

Card 2

Front

Name the parts of the eye in order from front to back.

Back

Cornea, pupil, iris, lens, ciliary muscle, suspensory ligaments, retina, blind spot and optic nerve.

Card 3

Front

Advantage and disadvantage of monocular vision.

Back

Preview of the front of card 3

Card 4

Front

Advantage and disadvantage of binocular vision.

Back

Preview of the front of card 4

Card 5

Front

Main problems of vision: short sighted?

Back

Preview of the front of card 5
View more cards

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