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The Nervous System & Neurones
The Nervous System Sends Information as Nerve Impulses

1. The nervous system is made of a complex network of cells called neurones. There are 3 main
types of neurone:
Sensory neurones ­ transmit nerve impulses from receptors to the central nervous system
(CNS) ­ the…

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The Structure of Sensory Neurones

1. All neurones have a cell body with a nucleus (plus
cytoplasm and all other organelles you usually get in a
2. The cell body has extensions that connect to other
neurones ­ dendrites carry nerve impulses towards the
cell body & axons carry…

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The sodiumpotassium pumps move sodium ions out of the neurones, but the membrane isn't
permeable to sodium ions, so they can't diffuse back in. This creates a sodium ion electrochemical
gradient (a concentration gradient of ions) because there are more positive sodium ions outside
the cell than inside.
The sodiumpotassium…


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