Heart Rate and Cardiac Cycle

Flashcards covering key vocabulary and concepts related to heart rate and the cardiac cycle.

Cardiac Cycle

The sequence of mechanical and electrical events that repeats with every heartbeat, or the period of time from the beginning of one heartbeat to the beginning of the next.

Heart Rate (HR)

The number of heart beats per minute.

Tachycardia

A condition where heart rate exceeds 100 beats per minute.

Bradycardia

A condition where heart rate falls below 50 beats per minute.

Vagal Tone

The continuous stream of inhibitory impulses reaching the heart via the vagus nerve, helping to control heart rate.

Vagal Escape

The escape of ventricles from the inhibitory effect of the vagus nerve.

End Diastolic Volume (EDV)

The volume of blood in the ventricle at the end of diastole, just before systole.

End Systolic Volume (ESV)

The volume of blood in the ventricle at the end of systole.

Stroke Volume (SV)

The volume of blood pumped by each ventricle per beat.

Ejection Fraction (EF)

Percentage of stroke volume to the end diastolic volume.

Normal Cardiac Output at Rest

About 5-6 liters per minute.

Physiological Regulation

Regulation of heart rate through nervous, chemical, and physical mechanisms.

Sympathetic Stimulation

Increased heart rate response to muscular exercise and physical activity.

Starling's Law of the Heart

The principle stating that increased venous return leads to increased cardiac output during diastole.

Heart Failure

An inability of the heart to push adequate blood for the needs of the tissues.

Cardiac Output (C.O.P)

The amount of blood pumped by each ventricle per minute, calculated as SV times HR.

Hypoxia

A condition of oxygen deficiency that causes an increase in heart rate.

Afterload Effect

The resistance the heart must overcome to eject blood during systole.

Preload Effect

The degree of stretch of cardiac muscle fibers before contraction, determined by venous return.