Cardiac Physiology and Conduction System

These flashcards cover key concepts from the lecture on cardiac physiology and the conduction system.

What are the phases of cardiac muscle cell action potentials?

The phases include depolarization, plateau phase, and repolarization.

What is the significance of the plateau phase in cardiac contractile cells?

The plateau phase allows for a sustained contraction, preventing tetany.

How does the firing rate of the SA node compare to that of the AV node?

SA node fires at 70-80 AP/min, while the AV node fires at 40-60 AP/min.

What is the normal range for resting heart rate in bpm?

60-100 bpm is considered normal.

What is bradycardia?

Bradycardia is a condition where the heart rate is less than 60 bpm.

What role does calcium play in myocardial contraction?

Calcium determines the force of myocardial contraction (contractility).

What is the function of the cardiac conduction system?

It produces coordinated heart chamber contractions.

Name the waveforms in a normal electrocardiogram (ECG).

The waveforms include P wave, QRS complex, and T wave.

What does the P wave represent in an ECG?

The P wave represents depolarization of the atria.

What is an ectopic pacemaker?

An ectopic pacemaker is an abnormal cell that generates a high rate of action potentials, bypassing the conducting system.

What is the conduction velocity of conduction fibers compared to ordinary muscle fibers?

Conduction fibers have a CV of 4.0 m/sec, while ordinary muscle fibers have a CV of 0.4 m/sec.

What electrical events does the QRS complex in an ECG represent?

The QRS complex represents depolarization of the ventricles.

What does the T wave indicate in an ECG?

The T wave indicates repolarization of the ventricles.

How do cardiac myofibers function with respect to syncytium?

Cardiac muscle functions as a syncytium, meaning it contracts as a single unit.

What happens during despolarization in the cardiac conduction system?

Depolarization spreads rapidly through the heart's conduction pathways, allowing for coordinated contractions.

What is the role of gap junctions in cardiac cells?

Gap junctions allow for electrical coupling between cardiac cells, facilitating the spread of action potentials.