Cardiac Cycle and Cardiovascular Physiology

Comprehensive vocabulary flashcards covering the cardiac cycle, heart sounds, electrical conduction system, ECG interpretation, autonomic regulation, and blood pressure dynamics based on the lecture material.

Atrial systole

The phase of the cardiac cycle where the heart atria contract while the ventricles relax (ventricular diastole).

Ventricular systole

The phase of the cardiac cycle where the ventricles contract while the atria relax (atrial diastole).

Passive blood flow

The movement of about $70\%$ of blood from the atria into the ventricles before atrial systole occurs.

Active blood flow (Atrial kick)

The movement of the remaining $30\%$ of blood pushed into the ventricles during atrial systole.

Lubb

The first heart sound occurring during ventricular systole, associated with the closing of the A-V valves.

Dupp

The second heart sound occurring during ventricular diastole, associated with the closing of the pulmonary and aortic semilunar valves.

Murmur

An abnormal heart sound resulting from the incomplete closure of valve cusps.

Functional Syncytium

A mass of cells that function as a unit, such as the cardiac muscle fibers in the atrial or ventricular walls.

Intercalated discs

Cell membranes separating cardiac muscle cells where electrical resistance is only $1/400$ the resistance through the outside membrane, allowing easy ion flow.

SA (Sinoatrial) Node

The pacemaker of the heart that initiates rhythmic contractions and is located in the right atrium.

AV (Atrioventricular) Node

Part of the conduction system that delays the impulse so atria finish contracting before ventricles start; it conducts impulses to the AV Bundle.

Purkinje Fibers

Large fibers that conduct impulses to the ventricular myocardium to trigger contraction.

P wave

The deflection on an ECG representing atrial depolarization, occurring just prior to atrial contraction.

QRS complex

A series of three waves on an ECG representing ventricular depolarization, occurring just prior to ventricular contraction.

T wave

The deflection on an ECG representing ventricular repolarization, occurring just prior to ventricular relaxation.

Parasympathetic impulses

Nerve impulses transmitted via the vagus nerves that decrease heart rate by influencing the SA and AV nodes.

Sympathetic impulses

Nerve impulses transmitted via accelerator nerves that increase heart rate and affect the ventricular myocardium.

Baroreceptor reflexes

Reflexes arising from the cardiac control center in the medulla oblongata that balance inhibitory and excitatory effects on the heart.

Fibrillation

Uncoordinated, chaotic contraction of small areas of the myocardium; ventricular fibrillation is often fatal.

Tachycardia

An abnormally fast heartbeat, defined as greater than $100\,\text{beats/min}$ at rest.

Bradycardia

An abnormally slow heartbeat, defined as less than $60\,\text{beats/min}$ at rest.

Flutter

A rapid, regular contraction of a heart chamber at a rate of $250-350\,\text{beats/min}$.

Ectopic Pacemaker

A secondary pacemaker, such as the AV node, that takes over if the SA node is damaged, pacing at $40-60\,\text{beats/min}$.

Systolic pressure (SP)

The maximum pressure reached in the systemic arteries during ventricular contraction.

Diastolic pressure (DP)

The minimum pressure remaining in the systemic arteries before the next ventricular contraction.

Pulse pressure (PP)

The difference between systolic and diastolic blood pressures ($SP - DP$).

Mean arterial pressure (MAP)

The average pressure in the arterial system, calculated as $\text{DP} + 1/3\,\text{PP}$, representing the force driving blood to tissues.

Depolarization

The electrical event where sodium ions ($Na^+$) enter the cell in response to a stimulus like acetylcholine.

Repolarization

The electrical event where potassium ions ($K^+$) leave the cell to restore the polarized state.