Spread of the nerve impulse Flashcards
What does the speed at which a nerve impulse travels along the axon depend on?
- the diameter of the axon
- if the axon is myelinated or not
- resistance
- capacitance (surface area)
What is the action potential threshold?
the depolarisation at which a neuron will fire an action potential
What is the absolute refractory period?
the cells cannot be stimulated to its threshold - all Na channels closed
What is the relative refractory period?
a stronger stimulus than normal could induce the action potential - some Na and more K channels open that normal
Which axons transmit the fastest?
large diameter axons with fewer channels
What is myelin?
a fatty sheath used to insulate the axon
What produces myelin in the peripheral nervous system?
Schwann cells
What produces myelin in the central nervous system?
Oligodendrocytes
What is saltatory conduction?
the propagation of action potentials along myelinated axons from one node to the next
What is the relationship between axon diameter and conduction velocity?
- for diameters above 1um myelinated axons are more efficient
- for diameters lower than that unmyelinated axons are more efficient
What is the cytoplasm of a nerve axon called?
axoplasm
