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Membrane Potentials
course pack
26
Anatomy
Undergraduate 2
11/09/2010

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Cards

Term
transmembrane potential
Definition
charges separated by membrane
Term
Skeletal Muscle RMP
Definition
-85 mV
Term
Cardiac Muscle RMP
Definition
-90 mV
Term
Neuron RMP
Definition
-70 mV
Term
resting membrane potential
Definition

negative charge inside of cell at equilibrium

 

Term
stimuli could
Definition

alter/change membrane permeability

 

effects membrane channels

Term
passive ion channels
Definition
channels that are always open
Term
active/gated channels
Definition

channels that open and close in response to stimuli. one of 3 states:

  1. open(activated)
  2. closed but capable of opening
  3. closed and incapable of opening

Term
ligand gated channels
Definition

chemicals can bind to receptors on gating proteins causing the channels to open or close

 

ex. acytocholine

 

Term
voltage-sensitive channels
Definition
gating proteins open or close channels in response to the charge across the membrane
Term
increased permeability to Na+ ions results in
Definition
depolarization
Term
increased permeability to K+ and Cl- ions results in
Definition
hyperpolarization
Term
action potential
Definition
produced when a local potential reaches threshold
Term
depolarization
Definition
result of increased membrane permeability to Na+ ions and movement of Na+ into cell
Term
Repolarization
Definition
result of decreased membrane permeability to Na+ ions which stops Na+ from entering the cell, and increased membrane permeability to K+ ions increasing K+ movement out of the cell
Term
Afterpotential
Definition
increased K+ ion permeability during repolarization lasts longer the time required to bring membrane to RMP
Term
Absolute Refractory Period
Definition
the time during an action potential when a second stimulus, no matter how strong, cannot initiate another action potential
Term
Relative Refractory Period
Definition
The time during which a stronger than threshold stimulus can evoke another action potential. Follows the absolute refractory period.
Term
synapse
Definition
transfers action potentials
Term
Chemical synapse
Definition
action potential in first cell results in release of a chemical which binds to receptors on second cell resulting in depolarization in Na+ channels open or hyperpolarization if K+ or Cl- channels open
Term
Electrical synapse
Definition
action potential passes directly from one cell to another
Term
subthreshold stimulus
Definition
only produces a local potential
Term
threshold stimulus
Definition
causes a local potential that reaches threshold and results in a single action potential
Term
maximal stimulus
Definition
a stimulus strong enough to produce the maximum frequency of action potentials
Term
submaximal stimulus
Definition
stimuli between threshold and maximal stimulus strength 
Term
supramaximal stimulus
Definition
any stimulus stronger than a maximal stimulus
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