action potential Flashcards
electrolytes
sodium (Na+)
potassium (K+)
polarization
electrical gradient (different electrical charge between inside and outside of neuron)
in resting potential, which is more negative?
inside is more negative than outside (i.e. -70 mV)
what does it mean when a neuron is in it’s resting potential?
it is stimulated and ready to fire
how are different charges maintained?
sodium-potassium pump: protein that allows 3 Na ions out and 2 K ions in
resting potential is…
disturbed by stimulation (by a neurotransmitter)
what is depolarization?
reduced polarization
threshold of excitation
-55 mV
stimulation that reaches the threshold leads to…
a massive depolarization of the neuron: action potential
what happens for depolarization?
sodium channels open and allow sodium inside
at the peak of the action potential, what happens?
sodium channels close; because the potassium channels are still open, polarization occurs and the membrane returns to its resting potential
what happens right after action potential?
the membrane is in a refractory period during which it resists the production of other action potentials
when does hyperpolarization occur?
the refractory period
what is hyperpolarization?
a time where the neuron cannot recharge as it goes below -70 mV
what is the all-or-none law?
signals are uniform in strength and speed
sheaths of myelin
insulating material (fats and protein); Schwann cells and oligodendrocytes
what is the usefulness of sheaths of myelin?
increases the speed; the action potential doesn’t have to regenerate at each single point
nodes (gaps) of ranvier
at the nodes, sodium ions enter the axon, push the positive charges to the next node to regenerate a new action potential (saltatory conduction)
corpus collosum
helps with right and left communication; connects the two sides
white matter
primarily axons; looks white because of myelin covering neurons
gray matter
made up of neuronal cell bodies and their dendrites
