Action Potential Flashcards
The nervous system sends both:
qualitative and quantitative information; uses combination of electrical and chemical signals
At what part of a neuron are action potentials generated
axon hillock
Depolarization means
positive and negative numbers are flipped
what do the plasma membrane of the nerve cell body and dendrites (somatodendritic domain) resemble
the basolateral plasma membrane domain of a polarized epithelial cell.
What do the plasma membrane of the axon and its nerve terminals resemble
the apical domain of an epithelial cell.
where do you see a graded (local) response
- in dendrites and cell body; only see PASSIVE spread of voltage
where do you see an all or none response
from axon hillock to terminus: refers to production of action potentials due to Na and K voltage gated channels
What does calcium do
releases neurotransmitters that are stored in nerve termini which bind to receptors on next order neuron w
what is hyperpolarization
a membrane potential more negative than at rest
what is a hyperpolarizing stimuli due to
either an efflux of cations or an influx of anions
What is depolarization
a membrane potential less negative or postive than at rest
What is a depolarization stimuli due to
either an influx of cation or an efflux of anions
what is threshold potential
the level of depolarization that triggers an action potential
what is action potential
a rapid, large regenerative depolarization
what is the amplitude of the voltage deflection across the membrane proportional to
the amplitude of the stimulus pulse (the current); the larger the stimulus, the larger the voltage deflection
what is resting potential
potential maintained across membrane of excitable cells (neurons, muscle)
what is summation
when you inc or dec a graded potential in order to fascilitate or prevent an active potential to be generated
Active potential is not summated
True
What is graded potential
Does not generate an action potential; its amplitude varies based on strength of stimuli; it can occur all along the axonal domain as long as any depolarization is less than the threshold.
Action potentials are:
all or none responses; needs to reach threshold or be above, it cant be below threshold.
What type of signal does a graded potential recieve? what about action potential
input; conduction
Where does graded potential occur? what about action potential?
dendrites and cell body; trigger zone through axon
what types of gated ion channels involved in graded potential? what bout action potential?
Na+, Cl- Ca+; Na and K
What type of signal does a graded potential recieve? what about action potential?
depolarizing or hyperpolarizing; depolarizing
what are the phases of the action potential
- rising phase
- falling phase
- after-hyperpolarization
what is the depolarizing phase
Opens up Na+ channel; starts pouring into cell.
What is the repolarizing phase
voltage becomes more neg bc you inactivate sodium channels and you open K+ channels
what is the hyperpolarization phase
K+ channels slowly closing, and Na+ channels go from inactive state to closing state.
What are three states of voltage gated sodium channels
- Open
- Closed
- Inactive
The positive feedback loop associated with the opening of the voltage gated Na channel is known as the:
Hodgkin cylce
what does refractory period refer to
unresponsive state; when membrane is refractory its because the voltage gated Na channels are in their inactive state and unable to open in response to a new depolarizing stimulus.
what is the one exception to the “all or none” law and the only time you would expect to see a non maximal voltage deflection during an action potential
relative refractory period; a smaller than normal height AP may be generated in response to a larger than usual stimulus.
