Cardiac Myocyte Electrical Properties Flashcards
How long is cardiac myocyte action potential compared to nerve action potentials?
Long action potentials
What causes the long action potential in myocytes?
Slow activation of delayed rectifying potassium currents
What does a rectifying potassium channel do?
Slowly pumps potassium out of the myocyte to restore the cell membrane potential
What occurs in stage 0?
Na channels open and Na concentrations increase in the cell
Causing rapid depolarization
What parts of the heart have the slowest stage 0?
SA node and AV node
What parts of the heart have the fastest stage 1?
Myocardium and Purkinje fibers
What does voltage-dependence ion channels mean?
The ion channels are dependent on an electrical gradient to function
What does time dependence ion channel mean?
Channels do not open and close immediately
What occurs in phase 1?
Potassium and chloride leave cell
What occurs in phase 2?
Calcium enters potassium leave cell
What occurs in phase 3?
Rectifier potassium channels open for it to leave the cell and repolarize further
What occurs in phase 4?
Baseline where the membrane potential is established
Which part of the heart has the longest action potential?
Ventricles
What properties about sodium channels are altered by antiarrhythmic drugs?
Time and voltage dependence
Which gates in sodium channels are activation?
M gates
