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The nervous system


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Nervous system
This allows you to react to what is going on around you
Sense organs
These detect stimuli. You have 5 of these which are your eyes, ears, nose, tongue and skin, they all have different receptors
Stimulus
This is a change in your environment which you may need to react to. You need to constantly monitor what is going on so you can respond if you need to. A stimulus can be light, sound, touch, pressure, pain, chemical, a change in position or temperature
Receptors
They are groups of cells which are sensitive to a stimulus. They change stimulus energy into electrical inpulses
The eye
This is a sense organ that contains light receptors. The light receptors have a nucleus, cytoplasm and a cell membrane and are sensitive to light
The ear
This is a sense organ and it contains sound receptors and balanced receptors. The sound receptors are sensitive to sound and the balance receptors are sensitive to changes in the position
The central nervous system
This is also known as the CNS. It coordinated a response to the stimuli. It is where all the information from the sense organ is sent. It consists of the brain and the spinal chord
Neurones
These are nerve cells that transmit information as electrical impulses very quickly to and from the central nervous system
Effectors
These are muscles and glands which respond according to the 'information' sent to them from the central nervous system
The nose
This is a sense organ that contains smell receptors and they are sensitive to chemical stimuli
The tongue
This is a sense organ that contains taste receptors, they are sensitive to bitter, salt, sweet and savoury chemical stimuli
The skin
This is a sense organ that is sensitive to touch, pressure, pain and temperature change
Sensory neurones
The nerve cells that carry electrical impulses from the receptors to the central nervous system
Relay neurones
The nerve cells that carry electrical impulses from the sensory neurones to the motor neurones
Motor neurones
The nerve cells that carry electrical impulses from the central nervous system to the effector muscle or gland
Muscle effectors
These contract in response to a nervous impulse
Gland effectors
These secrete hormones in response to nervous impulses