Neurophysiology of Neurons Flashcards
3 structures of a neuron
axon
dendrites
cell body (soma)
axon
transmits neural impulses away from cell body
tail of the neuron
myelin sheath
schwann cells and oligodendrocytes
surrounds the axon
node of ranvier
gap between two myelin sheath
dendrites
receive stimuli from its surroundings and conduct AP toward the cell body and axon
cell body (soma)
contains nucleus and most cytoplasm
produces neurotransmitters
resting potential of neurons
-70 mV (polarized state)
ion distribution in neurons
inside: high K+, low Na+ (negative charge)
outside: low K+, high Na+ (positive charge)
passive ion transport
ion channels composed of proteins with positive or negative charges that move across the cell membrane
ion-specific
transport from high to low concentration
active ion transport
Na+/K+ ion exchange pump
located across the axon’s plasma membrane
moves 3 Na+ OUT and 2 K+ IN for each pump cycle
transports against concentration gradient
why does ion transport happen?
because the neurons are trying to maintain equilibrium
action potential (AP)
how a neuron gets activated
generation of action potential
depolarization: Na+ floods into neurons (-70 mV to 30 mV)
repolarization: K+ flows out of neurons
absolute and relative refractory periods
3 characteristics of an action potential
- short lived (about 2 ms)
- all-or-nothing principle
- once AP is generated, its magnitude is not altered by increase or decrease of the stimulus level (the pattern does not change no matter the intensity level)
2 propagation (spread) patterns of an action potential
AP sweeps along the axon (unmyelinated fibers) saltatory propagation (myelinated fibers)
