chapter 9 Flashcards
Action potential:
an electrical impulse that stimulates cardiac muscle contraction
Arrythmia:
a disturbance or irregularity in the heart rate or rhythm
Blockage effect:
the action of antiarrhythmic drugs by blocking stimulation of β-receptors of the heart by adrenergic neurohormones
Cinchonism:
a term for quinidine toxicity
Depolarization:
the movement of a stimulus passing along the nerve, the positive ions move into the cell
Polarization:
a point at which the positive ions on the outside are equal to the negative ions on the inside of the cell
Proarrhythmic effect:
the development of a new arrhythmia or worsening of an already existing arrhythmia by administering an antiarrhythmic drug
Refractory period:
the period between transition of the nerve impulse along a nerve fiber
Repolarization:
the movement back of the ions to its original state after the impulse passes.
Threshold:
is the lowest intensity stimulus that will cause response
Atrial flutter:
rapid contraction of the atria more than 300 b/min
Atrial fibrillation:
irregular an rapid atrial contraction
Premature ventricular contractions:
beats originates in the ventricles instead of the SA-node, causing the ventricles to contract before the atria
Ventricular tachycardia:
rapid heart beat more than 100 beat/min
Ventricular fibrillation:
rapid disorganized contractions of the ventricles resulting in inability of the heart to pump blood, leading to death
Polarization
A state of a nerve cell with positive ions on the outside and negative ions on the inside
Depolarization
When the ions are moving around
Repolarization
When the ions are back in place
Class I
Membrane-stabilizing or anesthetic effect on the cells of the myocardium
Class II
decrease the myocardial response to epinephrine and nor epinephrine
Class III:
they prolong the refractory period
Action potential
Electrical impulse passing from cell to cell in the heart muscle
Refractory period
Period between the transmission of nerve impulses along a nerve fiber
Class I-A▪Action:
Depresses myocardial excitability
Class I-B•Action
Raises the threshold in the ventricular myocardium
Class I-C▪Action:
Decreases the height and rate of rise of cardiac action potentials
Uses of Antiarrhythmic Drugs
Used to prevent and treat cardiac arrhythmias
