The Human Nervous System

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Central nervous system

Back 1

Central nervous system (CNS), is made up of the neurons the brain or the spinal cord. The CNS receives information from sensory receptors all over the body. Information is processed and interpreted before the CNS initiates the suitable responses.

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Peripheral nerves

Back 2

Peripheral nerves, are the network of neurons, that carry information to and from the CNS. Peripheral nerves include sensory neurons, which carry information to the CNS, and motor neurons, which transmit impulses from the CNS to muscles and glands that then cause

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3 types of neurons

Back 3

There are 3 types of neurons in the nervous system:

- Sensory neurons (nerve cell that carries impulses to the CNS)

- Motor neurons (nerve cell that carries impulses away from the brain)

- Relay neurons (neurone through which a connection between a sensory and a motor neurone can be made)

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Dentrite

Back 4

A short cytoplasmic process of a neuron, which conducts action potentials towards the cell body.

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Axon

Back 5

a cytoplasmic process that transmits action potentials away from the cell body of a neuron.

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Myelin sheath

Back 6

A fatty covering around the axons of nerve fibres, which provides insulations.

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Resting potential

Back 7

The potential difference across the membrane of a neuron when it is not being stimulated.

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Depolarise

Back 8

To temporarily reverse the membrane potential of an axon as an impulse is transmitted.

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Action potential

Back 9

A rapid wave of depolarisation at a cell surface causing an impulse in a neuron.

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Threshold potential

Back 10

The potential difference beyond which an action must take place.

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Refactorary period

Back 11

The time after an action potential during which another action potential cannot occur.

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Nodes of Ranvier

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Gaps in the myelin sheath of an axon where the membrane can initiate action potentials.

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Saltatory conduction

Back 13

impulse conduction 'in jumps', between nodes of Ranvier.

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Synapse

Back 14

The connection between two nerve cells- a small gap that is bridged by a neurotransmitter.

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Neurotransmitter

Back 15

A substance produced and released by a neuron, which passes across a synapse and affects a post-synaptic membrane.

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Repolarisation

Back 16

Reenstablishment of the resting potential following depolarisation of a neuron.