Action Potential - Wilcox Flashcards
What is resting potential?
-70mV
How does the Na/K pump work?
Pumps 3 Na for ever 2 K
Needs ATP
Which ion has a high permeability and which has a low permeability?
K has high
Na is low (but concentration gradient is high!)
Where is graded potential located?
Soma and axon hillock
Where is action potential located
Axon
What is the difference between passive and active channels?
Passive- “leaky” channels allows ions to flow in; environment changes potential
Active- “gated” channels; open and close in response to stimuli; at resting potential gates are usually closed
What are the three classes of gated channels?
Chemical
Voltage
Mechanical
What is depolarization?
Change toward 0mV
Movement of Na through the channel
What is repolarization?
Change back toward -70mV
Go back to transmembrane potential
K leaves the cell
What is hyperpolarization?
Goes beyond -70mV
Usually too much K leaves the cell
What is the refractory period?
The time between stimuluses
From action potential to resting state
What is absolute refractory period?
Na gates closed
No possible action potential
What is relative refractory period?
Transmembrane potential almost back to normal
A large stimulus would stimulate an action potential
What is the difference between continuous and saltatory propagation?
Continuous- unmyelinated
Saltatory- myelinated; stimulus jumps
Describe the groups of axons
A- large diameter, myelinated, fastest
B- medium diameter, myelinated
C- small diambeter, unmyelinated, slowest
