Nerve Cells Flashcards
Define neuron
Nerves cell; basic functional and structural unit of the NS
What do all neurons consist of? (3) name and define
Cell body/soma: contain nerve cell nucleus
Axon: single long extensin of cytoplasm, carries nerve impulse away from cell body
Dendrites: branches of the cell body/soma, carries impulses towards cell body
What is the myelin sheath?
What fibres does and doesn’t it cover? (2)
Layer of fatty material covering axons
Unmyelinated fibre: fibre without myelin sheath
Myelinated fibre: fibre with myelin sheath
Define grey matter
Area with nerve cell bodies and unmyelinated fibres
Define white matter
Myelinated fibres
Define schwann cells?
Cells that wrap around the axon forming the myelin sheath
Define node of ranvier
Gaps in the myelin sheath that allow for saltatory conduction
Define neurilemma:
Outermost coil of schwann cell, helps in repair of damaged fibres
Function of the myelin sheath?
Insulation
Protects axon from damage
Increases speed of nerve impulses across a fibre
Define synapse
Junction between adjacent nerve fibres
Where do most synapses occur?
Between the axon terminals of one neuron and the dendrites of another
Name of the gap betweeen neuron and skeletal muscle?
Neuromuscular junction
Define sensory neuron?
Neuron that receives nerve impulse from receptors
Where does a sensory neuron carry an impulse?
Into the CNS spinal cord
Where are interneurons found?
between sensory and motor neurons, often in spinal cord and brain
