Neurons and nerve impulses
- Created by: sierrah
- Created on: 11-04-14 01:49
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- Nerve cells and impulses
- Two parts
- Central nervous system (CNS)
- Brain and spinal cord
- Peripheral nervous system (PNS)
- Nerves that connect the CNS with muscles, glands and reactors
- Central nervous system (CNS)
- Neuron (nerve cell)
- Basic structural/functional unit of the nervous system
- Vary in shape and size
- Consist of cell body and two extensions: axons and dendrites
- Structure
- Axon
- Often single long extension, carries nerve impulses away from cell body - EFFERENT PROCESS
- Dendrite
- Usually fairly short extension
- Carries nerve impulses towards cell body
- Schwann cell
- Produces myelin sheath, involved in repair of fibres
- Neurilemma
- Outer membrane of Schwann cell, maintains and regenerates fibres
- Myelin sheath
- Layer of fatty material
- Acts as insulator, assists with fibre repair, and speeds up nervous transmission
- Nodes of Ranvier
- Gaps in myelin sheath, speed up nervous transmission
- Synapse
- Junction between neurons, slowest part of transmission
- Cell body
- Mass of neuroplasm surrounding nucleus, directs activities of the rest of the cell
- Axon
- Types of neurons
- Sensory
- Conduct impulses from sensory organs/receptors to the CNS
- Motor
- Carry impulses from the CNS to effectors i.e. muscles/glands
- Connector/association
- Located in CNS
- Connect sensory/motor neurons
- Sensory
- Two parts
- Carries nerve impulses towards cell body
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