Chapter 6 Essential Terms

Antigen (AN-tih-jen)

A substance that is harmful, or perceived as harmful, to the body; typically bacteria, viruses, fungi, and toxins.

Aorta (ay-ORT-uh)

The largest artery of the human body.

Apex (AY-peks)

The lowest part of the exterior of the heart.

Arteries (AR-ter-eez)

Blood vessels that carry oxygenated blood from the heart to the organs, tissues, and cells of the body.

Arterioles (ar-TIR-ee-ols)

Small arterial branches that lead to capillaries.

Atrioventricular (AV) Node (ay-tree-oh-ven-TRIK-yoo-ler NOHD)

A small node of modified cardiac muscle fibers at the junction of the atria and ventricles.

Atrioventricular (AV) Valves (ay-tree-oh-ven-TRIK-yoo-ler VALVZ)

Valves located between the atrial and ventricular chambers in the right and left sides of the heart.

Auscultation (aws-kuhl-TAY-shun)

The use of a stethoscope to listen to the heart.

Bicuspid (Mitral) Valve (bigh-KUS-pid VALV)

The left AV valve, which has two flaps.

Blast (BLAST)

A large, immature cell that matures into a blood cell.

Blood (BLUD)

The fluid and its suspended formed elements that are circulated through the heart, arteries, capillaries, and veins.

Blood Cells (BLUD SELLS)

The solid component of blood; also known as the formed elements.

Blood Pressure (BLUD PRESH-ur)

The pressure exerted by the blood against the wall of an artery or vein.

Blood Type (BLUD TIGHP)

Classification of blood based on the presence or absence of antigens.

Blood Vessels (BLUD VES-sulz)

Vessels that convey blood; includes arteries, arterioles, capillaries, venules, and veins.

Bundle Branches (BUN-duhl BRAN-chus)

Conducting fibers that continue to pass on the electrical impulse in the cardiac conduction system.

Bundle of His (BUN-duhl OF HISS)

A slender bundle of modified cardiac muscle that conducts electrical impulses from the AV node to the left and right bundle branches.

Capillaries (KAP-ih-lair-eez)

Small, thin-walled blood vessels with semipermeable membranes to allow for gas exchange.

Cardiopulmonary (kar-dee-oh-PUL-muh-nair-ee)

The term for the functional interrelationship between the heart and the lungs.

Cardiovascular System (kar-dee-oh-VAS-kyoo-ler SIS-tum)

Body system that circulates oxygen-rich blood throughout the body; also known as the circulatory system.

Diastole (digh-AS-toh-lee)

Relaxation of the ventricles.

Diastolic Pressure (digh-uh-STAHL-ik PRESH-ur)

A measurement of blood pressure between heartbeats, when the heart is "resting" between contractions.

Endocardium (em-doh-KAR-dee-um)

The innermost layer of the heart that lines the four chambers and covers the valves of the heart.

Epicardium (EP-ih-kar-dee-um)

A thin, watery layer that forms the innermost layer of the pericardium.

Erythrocytes (uh-RITH-roh-sights)

Red blood cells.

Heart (HART)

A hollow, muscular, contractile organ located in the chest cavity.

Hemoglobin (HEE-moh-gloh-bin)

A protein that allows red blood cells to transport oxygen and carbon dioxide through the blood as the cells travel through the circulatory system.

Hemostasis (hee-moh-STAY-suhs)

Process of slowing down the flow of blood to enable blood clotting.

Inferior Vena Cava (in-FEER-ee-or VEE-nuh KAY-vuh)

A blood vessel that receives blood from the abdominopelvic organs and the lower extremities and empties the blood into the right atrium.

Left Atrium (LEFT AY-tree-um)

The atrium of the left side of the heart.

Left Ventricle (LEFT VEN-trih-kuhl)

The lower chamber on the left side of the heart.

Leukocytes (LOO-koh-sights)

White blood cells.

Lungs (LUNGZ)

Organs that coordinate the exchange of oxygen and carbon dioxide during the act of breathing.

Megakaryocytes (meg-uh-KAIR-ee-oh-sights)

Bone marrow cells with very large nuclei.

Myocardium (migh-oh-KAR-dee-um)

A layer of cardiac muscle that makes up the middle of the heart.

Nodal System (NOH-duhl SIS-tum)

A system responsible for electrical current conduction in the heart.

Pericardial Cavity (peer-ih-KAR-dee-uhl KAV-uh-tee)

The space between the pericardium and the epicardium.

Pericardium (peer-ih-KAR-dee-um)

The sac surrounding the heart.

Plasma (PLAS-muh)

The liquid component of blood.

Pulmonary Arteries (PUL-muh-nair-ee AR-ter-eez)

Blood vessels that derive from the pulmonary trunk and which enter the corresponding lungs.

Pulmonary Circulation (PUL-muh-nair-ee ser-kyoo-LAY-shun)

The process by which blood is pumped from the heart to the lungs and then back to the heart.

Pulmonary Trunk (PUL-muh-nair-ee TRUNK)

Blood vessel that originates from the right ventricle of the heart and divides into the right and left pulmonary trunks.

Purkinje Fibers (pur-KIN-jee FIGH-bers)

Fibers in the impulse-conducting network of the heart that rapidly transmit impulses through the ventricles.

Right Atrium (RIGHT AY-tree-um)

The atrium of the right side of the heart.

Right Ventricle (RIGHT VEN-trih-kuhl)

The lower chamber on the right side of the heart.

Semilunar Valves (sem-ee-LOO-nur VALVZ)

Two valves that each have a set of three crescent-shaped flaps; the pulmonary semilunar valve and the aortic semilunar valve.

Septum (SEP-tum)

A structure in the heart that divides the organ into the right heart and the left heart, creating a double pump.

Sinoatrial (SA) Node (sigh-noh-AY-tree-uhl NOHD)

The mass of specialized cardiac muscle fibers that acts as the "pacemaker" of the heart.

Sphygmomanometer (sfig-moh-muh-NOM-eh-ter)

An instrument used to measure blood pressure.

Superior Vena Cava (soo-PEER-ee-or VEE-nuh KAY-vuh)

A blood vessel that receives blood from the head, chest, and upper extremities and empties the blood into the right atrium of the heart.

Systemic Circulation (sis-TEM-ik ser-kyoo-LAY-shun)

The process by which the heart pumps blood to all parts and systems of the body.

Systole (SIS-toh-lee)

Contraction of the ventricles.

Systolic Pressure (sis-TAHL-ik PRESH-ur)

A measurement of blood pressure while the heart ventricles are contracting.

Thrombocytes (THROM-boh-sights)

Blood platelets.

Tricuspid Valve (trigh-KUS-pid VALV)

The right AV valve, which has three flaps.

Veins (VAYNZ)

Blood vessels that carry oxygen-poor blood to the heart.

Venules (VEEN-yools)

Tiny blood vessels that merge with the veins.