Conduction and Dysrhythmias Flashcards
Cardiac Muscle Cells: How does it function? (4 steps)
automaticity
excitability
conductivity
contractility
Automaticity: Definition
ability to generate an electrical impulse
Excitability: Definition
ability to respond to an outside impulse (chemical, mechanical, or electrical)
Conductivity: Definition
ability to receive an electrical impulse and conduct it
Contractility: Definition
ability of myocardial cells to shorten in response to an impulse (responsible for the “pump” part of the heart)
Cardiac Conduction: Action Potential: Order
P Wave
PR Segment (small straight line)
QRS Complex
T Wave
Isoelectric line (straight line)
What causes the P Wave?
atrial DEpolarization
the atria are squeezing
What causes the PR Segment (small straight line)?
delay at AV node
What causes the QRS Complex?
ventricular DEpolarization
the ventricles are squeezing
What causes the T Wave?
ventricular REpolarization
the ventricles are recharging
What causes the isoelectric line (straight line)?
no electrical activity
What causes these action potentials to occur?
Na+/K+ Pump
Normal Electrical Conductivity of the Heart
Rate: 60-100
Rhythm: regular
P Waves:
-upright and rounded
-one before every QRS
-regular rhythm
PR Interval: 0.12-0.20 sec
QRS: <0.12 sec
“sinus rhythm”
Sinus Arrhythmia
another NORMAL
-a degree of variability in the HR
-common in young people
-HR fluctuates with respiration or autonomic nervous system
-Intervals P Wave- P Wave are different
Dysrhythmia: Definition
Abnormality of the cardiac rhythm
Problem with impulse generation or conduction
