heart

Pericardium

Protective double-layered sac surrounding the heart that reduces friction and anchors the heart in the chest.

Myocardium

Thick muscular middle layer of the heart wall responsible for contracting and pumping blood.

Endocardium

Smooth inner lining of the heart chambers and valves that allows blood to flow easily.

Right Atrium

Upper right heart chamber that receives deoxygenated blood from the body through the superior and inferior vena cava.

Right Ventricle

Lower right chamber that pumps deoxygenated blood to the lungs through the pulmonary artery.

Left Atrium

Upper left chamber that receives oxygenated blood from the lungs through the pulmonary veins.

Left Ventricle

Lower left chamber that pumps oxygenated blood to the body through the aorta.

Aorta

Largest artery that carries oxygenated blood from the left ventricle to the body.

Pulmonary Artery

Vessel that carries deoxygenated blood from the right ventricle to the lungs.

Pulmonary Veins

Vessels that carry oxygenated blood from the lungs to the left atrium.

Vena Cava

Large veins that bring deoxygenated blood from the body back to the right atrium.

Tricuspid Valve

Valve between the right atrium and right ventricle that prevents blood from flowing backward.

Mitral (Bicuspid) Valve

Valve between the left atrium and left ventricle that prevents backflow of blood.

Pulmonary Semilunar Valve

Valve between the right ventricle and pulmonary artery that prevents blood from flowing back into the ventricle.

Aortic Semilunar Valve

Valve between the left ventricle and aorta that prevents blood from returning to the heart.

Heart Murmur

Abnormal heart sound caused by turbulent blood flow usually due to valve problems.

Coronary Arteries

Blood vessels that supply the heart muscle with oxygen and nutrients.

Myocardial Infarction

Heart attack caused by a blockage that stops blood flow to heart muscle.

Angina Pectoris

Chest pain caused by reduced oxygen supply to the heart muscle.

Pulmonary Circuit

Pathway where blood travels from the heart to the lungs and back to the heart to pick up oxygen.

Systemic Circuit

Pathway where oxygenated blood travels from the heart to the body and returns deoxygenated blood.

Cardiac Cycle

One complete heartbeat including contraction (systole) and relaxation (diastole).

Systole

Phase of the cardiac cycle when the heart contracts and pumps blood out.

Diastole

Phase of the cardiac cycle when the heart relaxes and fills with blood.

Cardiac Output

Amount of blood the heart pumps in one minute.

Stroke Volume

Amount of blood pumped by one ventricle with each heartbeat.

Heart Rate

Number of heartbeats per minute.

SA Node

Natural pacemaker in the right atrium that starts the electrical impulse for each heartbeat.

AV Node

Node that delays the electrical signal before it moves to the ventricles.

Bundle of His

Electrical pathway that carries impulses from the AV node to the ventricles.

Bundle Branches

Pathways that carry electrical signals down the interventricular septum.

Purkinje Fibers

Fibers that distribute the electrical impulse through the ventricles causing contraction.

P Wave

EKG wave representing atrial depolarization (atria contracting).

QRS Complex

EKG wave representing ventricular depolarization (ventricles contracting).

T Wave

EKG wave representing ventricular repolarization (ventricles relaxing).

Fibrillation

Rapid and irregular contractions of the heart that prevent effective pumping.

Tachycardia

Abnormally fast heart rate typically over 100 beats per minute.

Bradycardia

Abnormally slow heart rate typically below 60 beats per minute.

Ischemia

Reduced blood flow and oxygen supply to tissue.

Heart Block

Condition where electrical signals between atria and ventricles are slowed or blocked.