Action Potential Flashcards
Where is a graded potential located?
dendrites or cell bodies
Where is an action potential located?
Trigger zone (axon hillock)»_space; Axon
What type of ion channels are involved with a graded potential?
any type
What type of ion channels are involved with an action potential?
Voltage only (Na+, K+ only)
What type of signal is a graded potential?
Depolarizing or hyperpolarizing
What type of signal is an action potential?
Depolarizing only
What is the strength of a graded potential?
Depends, summation possible
What is the strength of an action potential?
Always the same
Cannot be summed
Refractory period obeyed
How is a graded potential initiated?
Ions through channel
How is an action potential initiated?
Above threshold graded potential at the axon hillock
What is an action potential?
A regenerating depolarization of membrane potential that propagates along an excitable membrane
Key features of an action potential
- All-or-none event
- Need to reach threshold
- Have constant amplitude
- Do not summate
- Initiated by depolarization
- Involve changes in permeability
- Rely on voltage-gated ion channels
3 Functions of Action Potentials
- Information delivery to CNS
- Information encoding
- Rapid transmission over distance (nerve cell APs)
What do local anesthetics do to action potentials?
Block APs in nerve cells
What happens after a local anesthetic is used?
Produces analgesia without paralysis