Glossary

Aorta: The largest artery in the body. The aorta carries oxygen-rich blood away from the heart, to the rest of the body.

Aortic Valve: 3-leafed valve that prevents blood from flowing backwards from the aorta into the heart.

Artery: A blood vessel that carries blood away from the heart. Most arteries carry oxygen-rich blood; only the pulmonary arteries (which travel from the heart to the lungs) carry deoxygenated blood.

Arteries: Blood vessels that carry blood away from the heart. Most arteries carry oxygen-rich blood; only the pulmonary arteries (which travel from the heart to the lungs) carry deoxygenated blood.

Atrioventricular Node: A group of autorhythmic (pacemaker) cells, located near the floor of the right atrium.

Atrium: One of the two (right and left) thin-walled upper chambers of the heart. (plural = atria)

Atria: Plural of atrium. The atrium is one of the two (right and left) thin-walled upper chambers of the heart.

Autorhythmic Cells: Special heart muscle cells that can produce electrical impulses without outside stimulation (i.e., they "beat" on their own). These cells control the rate of the heartbeat.

Bicuspid Valve: 2-leafed valve that prevents blood from flowing backwards from the left ventricle to the left atrium.

Blood: Bodily fluid that carries oxygen, nutrients, and other important substances (e.g. hornones, antibodies) throughout the body, and carries waste products (e.g. carbon dioxide) to places where they can be excreted.

Bundle of His: A bundle of special muscle fibres that carry electrical impulses through the septum of the heart.

Carbon Dioxide: A waste gas that is naturally made in our bodies, and is breathed out and replaced with oxygen.

Cardiac Veins: The blood vessels that carry carbon dioxide and waste products away from the muscle cells in the walls of the heart.

Conduction: The transmitting of electrical impulses from one place to another.

Conducting: Conduction is the transmission of electrical impulses from one place to another.

Contraction: The squeezing or tightening of a muscle.

Coronary Arteries: The blood vessels that carry oxygen and nutrients to the muscle cells in the walls of the heart.

Electrical Impulse: One of the ways cells communicate with each other. In the body, electrical impulses are created when positively (+) or negatively (-) charged atoms move in and out of cells very quickly.

Electrocardiogram (ECG): A recording of the electrical activity of the heart, made using electrodes placed on the skin.

Electrode: A device used to measure electric current.

Inferior Vena Cava: A large vein that delivers deoxygenated blood from the lower body into the heart.

Left anterior Descending Artery: A branch of the left coronary artery that carries blood to the septum and the front (anterior) wall of the heart.

Left Bundle Branch: A branch of the Bundle of His, which carries electrical impulses down the left side of the septum into the left ventricle.

Left Circumflex Artery: A branch of the left coronary artery, which carries blood to the left wall of the left ventricle.

Left Coronary Artery: Blood vessel that originates from the aorta and then divides into anterior and circumflex branches.

Lungs: Structures that inflate and deflate with air just like balloons. Everyone has 2 lungs, left and right. In the lungs, carbon dioxide travels from the blood to the air and oxygen travels from the air to the blood.

Mitral Valve: 2-leafed valve that prevents blood from flowing backwards from the left ventricle to the left atrium.

Non-Conducting Band: Fibrous ring of tissue that normally acts as an electrical insulator, so that the only conducting tissue between the atria and the ventricles is the Bundle of His.

Oxygen: An important gas that we breathe in from the air outside.  Oxygen replaces carbon dioxide in the blood. We use oxygen for energy and for keeping our bodies alive.

Pacemaker: Anything that controls the rate of the heartbeat.

Pulmonary Arteries: Blood vessels that carry deoxygenated blood from the heart to the lungs.

Pulmonary Trunk: The main pulmonary artery, that branches into many smaller arteries.

Pulmonary Valve: 3-leafed valve that prevents blood from flowing backwards from the pulmonary trunk into the right ventricle.

Pulmonary Veins: Blood vessels that carry oxygenated blood from the lungs to the heart.

Purkinje Fibres: Specialized heart muscle fibres that rapidly conduct electrical impulses to all parts of the ventricles.

Right Coronary Artery: Blood vessel that originates at the aorta and carries blood to the front (anterior) of the right side of the heart, and in most cases, to the back (posterior) of the heart.

Right Bundle Branch: A branch of the Bundle of His, which carries electrical impulses down the right side of the septum into the right ventricle.

Septum: The thin wall that separates the right side of the heart from the left side.

Sinoatrial node: A group of autorhythmic (pacemaker) cells, located in the right atrium, near the entry of the superior vena cava. The sinoatrial node is normally the main pacemaker of the heart.

Superior vena cava: A large vein that delivers deoxygenated blood from the upper body into the heart.

Tricuspid Valve: 3-leafed valve that prevents blood from flowing backwards from the right ventricle to the right atrium.

Vein: A blood vessel that carries blood towards the heart. Most veins carry deoxygenated blood; only the pulmonary veins (which travel from the lungs to the heart) carry oxygenated blood.

Ventricle: One of the two (right and left) muscular lower chambers of the heart.