Chapter 7:The Sensory System
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Anything that causes us to tke an action is called a stimulus
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The body uses the nervous system as a method of communication
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The central nervous system consists of the brain and the spinal chord
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Animals need to be able to sense what is happening around them
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Animals have 5 means of taking in information frok around them. These 5 means are the senses
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The 5 senses ate touch, sight, hearing, taste and smell
The Nervous System:
The 5 Senses:
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Each sense has a stimulus and an organ which allows for this sense
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Sight: Stimulus-Light Organ- Eyes
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Touch: Heat/Pressure Organ- Skin
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Hearing: Vibrations Organ- Ears
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Smell: Chemicals Organ- Nose
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Taste: Chemical Organ- Tongue
The Eye:
Parts and Functions of the Eye
Part: Function
Optic Nerve Sends impulses or nerve signals to the brain
Retina Detects light and produces nerve signals
Cornea Bends light rays and allows it to pass through the sclera (one of layers of the eye)
Iris Controls the amount of light that enters the eye
Lens Focuses light on the Retina
Pupil Allows light to enter the eye
Cilairy Muscle Changes shape of the lens
Sensory and Motor Neuron:
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There are two types of neuron- Sensory neuron and motor neuron
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Sensory neurons send impulses towards the central nervous system from the sensory organs e.g Optic nerve sends impulses from eye to brain
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Motor neurons send impulses away from the central nervous system towrads the muscles or glands e.g brain sends signal to muscle to move upwards
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A way of remembering the difference between the two is sensory neurons -sense and motor neurons-Muscles. S for s and M for m.
