Unit 3: Chapter 27 - Neurons and Neural Pathways

  • Created by: chloe
  • Created on: 09-04-13 16:33
What are the 3 types of neurones?
Sensory, association and motor
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What is a dendrite?
A nerve fibre which carries impulses to the cell body
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what is an axon?
A nerve fibre which carries impulses away from the cell body, sometimes to another neurone. Axons may end in tiny axon branches
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What type of sheath covers long nerve fibres and what is the function of it?
A myelin sheath. This greatly increases the speed of the transmission of the impulse. It is made up of double layers of plasma membrane so it is a fatty material
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Describe the structure of a sensory neurone
These have several dendrites which are in contact with sense receptors. They merge to form a long fibre which carries impulses to the cell body. They have a short axon which connects with neurones in the CNS
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Describe the structure of an association neurone
These are only found in the CNs. They have many dendrites which connect each other. The dendrites and axon are comparitively short
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Describe the structure of a motor neurone
They have short dendrites which run from other neurones in the CNS to the cell body. They have a very long axon
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In which direction do impulses pass through the cell body
Dendrite > cell body > axon
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What is a synapse?
A small gap which occurs between the axon ending (synaptic knob) of one neurone and the dendrite of the next neurone
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What does multiple sclerosis involve?
The breakdown of the myelin sheaths by the body's own immune system. This means that nerve impulses are not transmitted efficiently, resulting in numbness, balance difficulties, impaired vision etc
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What is the nerve cell that is before the synapse call?
Presynaptic nerve
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What is the nerve cell that is after the synapse called?
Postsynaptic nerve
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What is the name of the area of contact between a motor neurone and an effector called?
neuro-effector
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What is the connection between a nerve and muscle fibres called?
neuromuscular junction
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What is a neuotransmitter?
A chemical which allows a message to be passed across a synapse
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Give an example of a neurotransmitter
Acetylcholine/noradrenaline
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When do diverging neural pathways occur?
When the route along which an impulse travels is divided
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What does a diverging pathway do?
It allows a message to be transmitted to several destinations (eg when the cerebrum is controlling the fingers and thumb)
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What do converging neural pathways do?
They bring impulses from several receptors together into one destination
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Other cards in this set

Card 2

Front

What is a dendrite?

Back

A nerve fibre which carries impulses to the cell body

Card 3

Front

what is an axon?

Back

Preview of the front of card 3

Card 4

Front

What type of sheath covers long nerve fibres and what is the function of it?

Back

Preview of the front of card 4

Card 5

Front

Describe the structure of a sensory neurone

Back

Preview of the front of card 5
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