Cardiac Physiology

These flashcards cover key concepts related to cardiac physiology, including the electrical system of the heart, the cardiac cycle, and electrocardiogram interpretation.

What initiates the electrical activity of the heart?

The sinoatrial (SA) node initiates the electrical activity of the heart.

What happens during depolarization of contractile cells?

Depolarization spreads from autorhythmic cells to contractile cells via gap junctions.

What is the normal heart rate range in beats per minute (BPM)?

The normal heart rate range is approximately 72 to 75 beats per minute.

What does the P wave represent in an electrocardiogram (ECG)?

The P wave represents atrial depolarization.

What is the significance of the QRS complex in an ECG?

The QRS complex represents ventricular depolarization.

What does the T wave represent in an ECG?

The T wave represents ventricular repolarization.

What is the primary function of the cardiac cycle?

The cardiac cycle encompasses all events associated with one heartbeat, including contraction (systole) and relaxation (diastole).

What is stroke volume?

Stroke volume is the amount of blood pumped by a ventricle in one cardiac cycle.

What does the Frank-Starling Law of the Heart state?

The Frank-Starling Law states that the more the heart is stretched, the more forcefully it contracts.

What influences heart rate during physical and emotional stress?

The sympathetic nervous system increases heart rate during physical and emotional stress.

How does the parasympathetic nervous system affect heart rate?

The parasympathetic nervous system slows the heart rate to allow it to rest during non-crisis times.

What is ejection fraction?

Ejection fraction is the percentage of end-diastolic volume (EDV) ejected with one contraction.

What is cardiac output?

Cardiac output is the volume pumped by each ventricle in one minute.

What determines venous return to the heart?

Venous return is primarily determined by the skeletal muscle pump and respiratory pump.

What is the role of the atrioventricular (AV) node in the conduction system?

The AV node delays the electrical impulse by approximately 0.1 seconds before transmitting it to the ventricles.

What conditions can result in abnormal ECG readings?

Conditions such as atrial fibrillation and ventricular fibrillation can result in abnormal ECG readings.

What characterizes junctional rhythm in an ECG?

In junctional rhythm, there is no P wave, and the heart rate is set by the AV node, typically between 40-60 beats per minute.