|
Home > Preview
The flashcards below were created by user
ebacker
on FreezingBlue Flashcards.
-
What causes membrane potential changes?
- Gated channels
- Open/close in response to stimuli
- Affect mvmt of ions - electrical signal
-
What are the 3 types of gated channels?
1. Voltage gated - change in elec
2. Ligand (chemically) gated - messenger
3. Mechanically gated - sensory perception
-
What are the 4 different polar states of a neuron?
- Resting potential (reference pt)
- Depolarization
- Repolarization
- Hyperpolarization
-
What are the 2 types of potential changes?
1. Graded Potentials
2. Action Potentials
-
What are the properties of graded potentials?
- Initiated by stimulus
- Small changes in MP
- Magnitude varies with strength of stimulus
- Short distance, decremental
- Spread by electrotonic conduction
-
What is the purpose of graded potentials?
Determine whether or not an action potential will occur
-
What is the threshold voltage needed for an action potential?
-55 mV
-
What causes excitation of a neuron? ...inhibition?
Depolarization
Hyperpolarization
-
What are the 2 types of summation in graded potentials?
1. Temporal Summation - same stimulus, repeated close together in time
2. Spatial Summation - different stimuli, overlap in time
-
What is an Action Potential?
Rapid, large depolarization of membrane potential for communication
-
What are the phases of an Action Potential?
- Phase 1. Depolarization
- Phase 2. Repolarization
- Phase 3. After-hyperpolarization
-
What causes rapid depolarization of the membrane?
Permeability change from K+ > Na+ to Na+ >> K+
Voltage gated Na+ channels open, Na+ rushes in, results in positive Vm
-
What does the Threshold trigger?
- Rapid opening of Na+ channels ( + feedback)
- Slow closing of Na+ channels
- Slow opening of K+ channels
-
What are the 2 gates associated with voltage-gated Na+ channels and what are their properties?
1. Activation Gate - voltage dependent, opens at threshold, (+) feedback
2. Inactivation Gate - voltage & time dependent, close/open during depolarization
-
What are the properties of voltage-gated K+ channels?
- One gate
- Voltage and time dependent
- (-) feedback
-
Define Threshold.
Minimum depolarization necessary to induce the regenerative mechanism for the opening of sodium channels.
-
What is a Refractory Period?
Period of time following an action potential, marked by decreased excitability.
-
What are the 2 types of Refractory Periods?
- Absolute
- Relative
-
What are the properties of absolute refractory periods?
- Spans all of depolarization and most of the repoarizatioin phase.
- Second action potential cannot be generated.
- Na+ gates are inactivated.
-
What are the properties of relative refractory periods?
- Spans last part of repolarization phase and hyperpolarization.
- Second action potential can be generated by stronger stimulus.
- Some Na+ gates closed, some inactivated, some open.
-
What are the consequences of refractory periods?
- All-or-none
- Frequency coding
- Unidirectional propagation of actions potentials
-
What does the speed and distance of conduction depend on?
Diameter and Mylenation
-
How is neural stability maintained?
Na+ and K+ pump prevents dissipation caused by graded potentials
|
|
Get the free mobile app
Take the Quiz
Learn more
Learn more