Action Potential

The change in the electrical potential of the heart muscle when it is stimulated; depolarization followed by repolarization.

Aorta

The largest artery of the body; transport blood from the left ventricle of the heart to the entire body.

Aortic Semilunar Valve

Valve located in the aorta that prevents the backflow of blood into the left ventricle.

Atrioventricular (AV) Node

Delays the electrical impulse to allow the atria to complete their contraction.

Atrium (Pl. Atria)

Top two chambers of the heart.

Automaticity

The ability of the heart to initiate an electrical impulse without being stimulated by another or independent source.

Bundle Branches

Left and right branches pf the bundle of His that conduct impulse down either side of the interventricular septum, to the left and right ventricles.

Bundle of His (AV Bundle)

Located next to the AV node; provides the transfer of the electrical impulse from the atria to the ventricles.

Cardiac Cycle

The contraction and relaxation of the heart

Complexes

Atrial or ventricular contraction as they appear on the ECG; complete ECG waveforms.

Conductivity

The ability of the heart cells to receive and transmit an electrical impulse.

Contractility

The ability of the heart muscle cells to shorten in response to an electrical stimulus.

Coronary Circulation

The circulation of the blood to and from the heart.

Deoxygenated Blood

Blood that has little or minimal oxygen (oxygen-poor blood)

Depolatization

The electrical activation of the cells of the heart that initiates contraction of the heart muscle.

Diastole

The phase of the cardiac cycle when the heart is expanding and refilling; also known as the relaxation phase.

Excitability

The ability of the heart muscle cells to respond to an impulse or stimulus.

Interval

The period of time between two activities within the heart.

Interventricular Septum

A partition or wall (septum) that divides the right and left ventricles.

Ischemia

Lack of blood supply entrance into a body cavity, tissue, or blood vessel.

Left Atrium

The left upper chamber of the heart, which receives blood from the lungs.

Left Ventricle

The left lower chamber of the heart, which pumps oxygenated blood through the body, it is the biggest and strongest chamber, known as the workhorse of the heart.

Mitral (Bicuspid) Valve

Valve with two cups or leaflets located between the left atrium and left ventricle; it prevents backflow of blood into the left atrium.

Myocardial

Pertaining to the heart (cardio) muscle (myo)

Oxygenated Blood

Blood having oxygen (oxygen-rich blood)

Pericardium

A two-layered sac of tissue enclosing the heart.

Polaraztion

The stare of cellular rest in which the inside is negatively charge and the outside is positively charged.

Pulmonary Artery

Large artery that transports deoxygenated blood from the right ventricle to the lungs. This is the only artery in the body that carries deoxygenated blood.

Pulmonary Circulation

The transportation of blood to and from the lungs; blood is oxygenated in the lungs during pulmonary circulation.

Pulmanary Semilaunar Valve

A valve found in the pulmonary artery that prevents backflow of the blood back into the right ventricle during pulmonary circulation.

Pulmoanary Vein

Transports oxygenated blood back into the left atrium of the heart.

Purkinje Fibers

The fibers within the heart that distribute electrical impulses from cell to cell throughout the ventricles.

Purkinje Network

Spreads the electrical impulse throughout the ventricles by means of the Purlkinje fiber.

Repolarization

When heart muscle cells return to their resting electrical state and the heart muscle relaxes.

Right Atrium

The right upper chamber of the heart, which receives blood from the body.

Right Ventricle

The right lower chamber of the heart, which pumps blood to the lungs.

Segment

A portion or part of the electrical tracing produced by the heart.

Semilunar Valve

A valve with half-moon-shaped cusps that open and close, allowing blood to travel only one way; located in the pulmonary artery and the aorta.

Sinoatrial (SA) Node

An area of specialized cells in the upper right atrium that initiates the heartbeat.

Systemic Circulation

The pathways for pumping blood throughout the body and back to the heart.

Systole

The contraction phase of the cardiac cycle, during which the heart is pumping blood out of the body.

Tricuspid Valve

Valve located between the right atrium and right ventricle; it prevents backflow of blood into the right atrium.

Vena Cava (Pl. Venae Cave)

Largest vein in the body, which provides a pathway for deoxygenated blood to return to the heart; its upper portion, the superior vena cava, transports blood from the head, arms, and upper body; and its lower portion, the inferior vena cava, transports blood from the lower body legs.