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Graded and Action Potentials - Coggle Diagram
Graded and Action Potentials
Action potential
nerves send signals through action potentials
action potentials are caused by ions moving in or out of a cell
sodium outside of cell and potassium inside of cell creates a
resting membrane potential.
it is more positive outside and more negative inside (-70 mV)
when a neuron is stimulated, glutamate binds to receptors and allows sodium to rush into the cell, making it more positive
once enough sodium is let in, the charge will rise to -55 mV (threshold) and open voltage-gated sodium channels (
depolarization
begins)
it becomes so positive inside the cell that it reaches 40 mV (
crest
) - at this point the
voltage-gated sodium channel
closes
at 40 mV,
voltage-gated potassium channels
are opened, causing the charge to fall back (
repolarization
),
hyperpolarization
occurs, and shortly goes back to resting membrane potential
Graded Potential
when multiple channels at different areas open up and let positive ions in, the positive charge reaches threshold and
causes an action potential to occur
when one channel opens and lets positive ions in over time,
an action potential will be
reached
excitatory neurotransmitters like glutamate allow positive ions into cell causing it to become more positive
3 Major Phases
Resting Membrane Potential
sodium potassium pumps
actively pump in 2 K while pumping out 3 Na - this creates and maintains a gradient
only channel active is
leak potassium channel
Depolarization
sodium potassium pump
still active - now
voltage-gated sodium channels
open up
sodium floods the cell and causes the it to become positive (40 mV)
leak potassium channel
is still active
Repolarization
sodium potassium pump
still active - now
voltage-gated potassium channels
open
potassium flows back into the cell causing it to become more negative - charge plummets back down causing hyperpolarization and then resting membrane potential
