Skip to main content
Biology LibreTexts

9.6: Glossary- The Circulatory System

  • Page ID
    40624
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

    ( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\id}{\mathrm{id}}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\kernel}{\mathrm{null}\,}\)

    \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\)

    \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\)

    \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    \( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

    \( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

    \( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vectorC}[1]{\textbf{#1}} \)

    \( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

    \( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

    \( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    Glossary

    albumin most abundant plasma protein, accounting for most of the osmotic pressure of plasma

    anastomosis (plural = anastomoses) area where vessels unite to allow blood to circulate even if there may be partial blockage in another branch

    anterior cardiac veins vessels that parallel the small cardiac arteries and drain the anterior surface of the right ventricle; bypass the coronary sinus and drain directly into the right atrium

    anterior interventricular artery (also, left anterior descending artery or LAD) major branch of the left coronary artery that follows the anterior interventricular sulcus

    anterior interventricular sulcus sulcus located between the left and right ventricles on the anterior surface of the heart

    antibodies (also, immunoglobulins or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses

    aortic valve (also, aortic semilunar valve) valve located at the base of the aorta

    arteriole (also, resistance vessel) very small artery that leads to a capillary

    arteriovenous anastomosis short vessel connecting an arteriole directly to a venule and bypassing the capillary beds

    artery blood vessel that conducts blood away from the heart; may be a conducting or distributing vessel

    atrioventricular septum cardiac septum located between the atria and ventricles; atrioventricular valves are located here

    atrioventricular valves one-way valves located between the atria and ventricles; the valve on the right is called the tricuspid valve, and the one on the left is the mitral or bicuspid valve

    atrium (plural = atria) upper or receiving chamber of the heart that pumps blood into the lower chambers just prior to their contraction; the right atrium receives blood from the systemic circuit that flows into the right ventricle; the left atrium receives blood from the pulmonary circuit that flows into the left ventricle

    auricle extension of an atrium visible on the superior surface of the heart

    bicuspid valve (also, mitral valve or left atrioventricular valve) valve located between the left atrium and ventricle; consists of two flaps of tissue

    blood liquid connective tissue composed of formed elements—erythrocytes, leukocytes, and platelets—and a fluid extracellular matrix called plasma; component of the cardiovascular system

    buffy coat thin, pale layer of leukocytes and platelets that separates the erythrocytes from the plasma in a sample of centrifuged blood

    capacitance ability of a vein to distend and store blood

    capacitance vessels veins

    capillary smallest of blood vessels where physical exchange occurs between the blood and tissue cells surrounded by interstitial fluid

    capillary bed network of 10–100 capillaries connecting arterioles to venules

    cardiac notch depression in the medial surface of the inferior lobe of the left lung where the apex of the heart is located

    cardiac skeleton (also, skeleton of the heart) reinforced connective tissue located within the atrioventricular septum; includes four rings that surround the openings between the atria and ventricles, and the openings to the pulmonary trunk and aorta; the point of attachment for the heart valves

    cardiomyocyte muscle cell of the heart

    chordae tendineae string-like extensions of tough connective tissue that extend from the flaps of the atrioventricular valves to the papillary muscles

    circumflex artery

    continuous capillary most common type of capillary, found in virtually all tissues except epithelia and cartilage; contains very small gaps in the endothelial lining that permit exchange

    coronary arteries branches of the ascending aorta that supply blood to the heart; the left coronary artery feeds the left side of the heart, the left atrium and ventricle, and the interventricular septum; the right coronary artery feeds the right atrium, portions of both ventricles, and the heart conduction system

    coronary sinus large, thin-walled vein on the posterior surface of the heart that lies within the atrioventricular sulcus and drains the heart myocardium directly into the right atrium

    coronary sulcus sulcus that marks the boundary between the atria and ventricles

    coronary veins vessels that drain the heart and generally parallel the large surface arteries

    elastic artery (also, conducting artery) artery with abundant elastic fibers located closer to the heart, which maintains the pressure gradient and conducts blood to smaller branches

    endocardium innermost layer of the heart lining the heart chambers and heart valves; composed of endothelium reinforced with a thin layer of connective tissue that binds to the myocardium

    endothelium layer of smooth, simple squamous epithelium that lines the endocardium and blood vessels

    epicardial coronary arteries surface arteries of the heart that generally follow the sulci

    epicardium innermost layer of the serous pericardium and the outermost layer of the heart wall

    external elastic membrane membrane composed of elastic fibers that separates the tunica media from the tunica externa; seen in larger arteries

    fenestrated capillary type of capillary with pores or fenestrations in the endothelium that allow for rapid passage of certain small materials

    fibrinogen plasma protein produced in the liver and involved in blood clotting

    foramen ovale opening in the fetal heart that allows blood to flow directly from the right atrium to the left atrium, bypassing the fetal pulmonary circuit

    formed elements cellular components of blood; that is, erythrocytes, leukocytes, and platelets

    fossa ovalis oval-shaped depression in the interatrial septum that marks the former location of the foramen ovale

    globulins heterogeneous group of plasma proteins that includes transport proteins, clotting factors, immune proteins, and others

    great cardiac vein vessel that follows the interventricular sulcus on the anterior surface of the heart and flows along the coronary sulcus into the coronary sinus on the posterior surface; parallels the anterior interventricular artery and drains the areas supplied by this vessel

    hematocrit (also, packed cell volume) volume percentage of erythrocytes in a sample of centrifuged blood

    hypertrophic cardiomyopathy pathological enlargement of the heart, generally for no known reason

    immunoglobulins (also, antibodies or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses

    inferior vena cava large systemic vein that returns blood to the heart from the inferior portion of the body

    interatrial septum cardiac septum located between the two atria; contains the fossa ovalis after birth

    internal elastic membrane membrane composed of elastic fibers that separates the tunica intima from the tunica media; seen in larger arteries

    interventricular septum cardiac septum located between the two ventricles

    left atrioventricular valve (also, mitral valve or bicuspid valve) valve located between the left atrium and ventricle; consists of two flaps of tissue

    lumen interior of a tubular structure such as a blood vessel or a portion of the alimentary canal through which blood, chyme, or other substances travel

    marginal arteries branches of the right coronary artery that supply blood to the superficial portions of the right ventricle

    mesothelium simple squamous epithelial portion of serous membranes, such as the superficial portion of the epicardium (the visceral pericardium) and the deepest portion of the pericardium (the parietal pericardium)

    metarteriole short vessel arising from a terminal arteriole that branches to supply a capillary bed

    microcirculation blood flow through the capillaries

    middle cardiac vein vessel that parallels and drains the areas supplied by the posterior interventricular artery; drains into the great cardiac vein

    mitral valve (also, left atrioventricular valve or bicuspid valve) valve located between the left atrium and ventricle; consists of two flaps of tissue

    moderator band band of myocardium covered by endocardium that arises from the inferior portion of the interventricular septum in the right ventricle and crosses to the anterior papillary muscle; contains conductile fibers that carry electrical signals followed by contraction of the heart
    myocardium thickest layer of the heart composed of cardiac muscle cells built upon a framework of primarily collagenous fibers and blood vessels that supply it and the nervous fibers that help to regulate it

    nervi vasorum small nerve fibers found in arteries and veins that trigger contraction of the smooth muscle in their walls

    packed cell volume (PCV) (also, hematocrit) volume percentage of erythrocytes present in a sample of centrifuged blood

    papillary muscle extension of the myocardium in the ventricles to which the chordae tendineae attach pectinate muscles muscular ridges seen on the anterior surface of the right atrium perfusion distribution of blood into the capillaries so the tissues can be supplied
    pericardial cavity cavity surrounding the heart filled with a lubricating serous fluid that reduces friction as the heart contracts pericardial sac (also, pericardium) membrane that separates the heart from other mediastinal structures; consists of two distinct, fused sublayers: the fibrous pericardium and the parietal pericardium pericardium (also, pericardial sac) membrane that separates the heart from other mediastinal structures; consists of two distinct, fused sublayers: the fibrous pericardium and the parietal pericardium

    plasma in blood, the liquid extracellular matrix composed mostly of water that circulates the formed elements and dissolved materials throughout the cardiovascular system

    platelets (also, thrombocytes) one of the formed elements of blood that consists of cell fragments broken off from megakaryocytes

    posterior cardiac vein vessel that parallels and drains the areas supplied by the marginal artery branch of the circumflex artery; drains into the great cardiac vein posterior interventricular artery (also, posterior descending artery) branch of the right coronary artery that runs along the posterior portion of the interventricular sulcus toward the apex of the heart and gives rise to branches that supply the interventricular septum and portions of both ventricles posterior interventricular sulcus sulcus located between the left and right ventricles on the anterior surface of the heart precapillary sphincters circular rings of smooth muscle that surround the entrance to a capillary and regulate blood flow into that capillary
    pulmonary arteries left and right branches of the pulmonary trunk that carry deoxygenated blood from the heart to each of the lungs pulmonary capillaries capillaries surrounding the alveoli of the lungs where gas exchange occurs: carbon dioxide exits the blood and oxygen enters pulmonary circuit blood flow to and from the lungs pulmonary trunk large arterial vessel that carries blood ejected from the right ventricle; divides into the left and right pulmonary arteries pulmonary valve (also, pulmonary semilunar valve, the pulmonic valve, or the right semilunar valve) valve at the base of the pulmonary trunk that prevents backflow of blood into the right ventricle; consists of three flaps pulmonary veins veins that carry highly oxygenated blood into the left atrium, which pumps the blood into the left ventricle, which in turn pumps oxygenated blood into the aorta and to the many branches of the systemic circuit

    red blood cells (RBCs) (also, erythrocytes) one of the formed elements of blood that transports oxygen

    right atrioventricular valve (also, tricuspid valve) valve located between the right atrium and ventricle; consists of three flaps of tissue semilunar valves valves located at the base of the pulmonary trunk and at the base of the aorta septum (plural = septa) walls or partitions that divide the heart into chambers septum primum flap of tissue in the fetus that covers the foramen ovale within a few seconds after birth sinusoid capillary rarest type of capillary, which has extremely large intercellular gaps in the basement membrane in addition to clefts and fenestrations; found in areas such as the bone marrow and liver where passage of large molecules occurs small cardiac vein parallels the right coronary artery and drains blood from the posterior surfaces of the right atrium and ventricle; drains into the great cardiac vein sulcus (plural = sulci) fat-filled groove visible on the surface of the heart; coronary vessels are also located in these areas superior vena cava large systemic vein that returns blood to the heart from the superior portion of the body systemic circuit blood flow to and from virtually all of the tissues of the body

    thoroughfare channel continuation of the metarteriole that enables blood to bypass a capillary bed and flow directly into a venule, creating a vascular shunt

    trabeculae carneae ridges of muscle covered by endocardium located in the ventricles tricuspid valve term used most often in clinical settings for the right atrioventricular valve

    tunica externa (also, tunica adventitia) outermost layer or tunic of a vessel (except capillaries)

    tunica intima (also, tunica interna) innermost lining or tunic of a vessel

    tunica media middle layer or tunic of a vessel (except capillaries)

    valve in the cardiovascular system, a specialized structure located within the heart or vessels that ensures one-way flow of blood

    vasa vasorum small blood vessels located within the walls or tunics of larger vessels that supply nourishment to and remove wastes from the cells of the vessels

    vascular shunt continuation of the metarteriole and thoroughfare channel that allows blood to bypass the capillary beds to flow directly from the arterial to the venous circulation

    vasoconstriction constriction of the smooth muscle of a blood vessel, resulting in a decreased vascular diameter

    vasodilation relaxation of the smooth muscle in the wall of a blood vessel, resulting in an increased vascular diameter

    vasomotion irregular, pulsating flow of blood through capillaries and related structures

    vein blood vessel that conducts blood toward the heart

    venous reserve volume of blood contained within systemic veins in the integument, bone marrow, and liver that can be returned to the heart for circulation, if needed

    ventricle one of the primary pumping chambers of the heart located in the lower portion of the heart; the left ventricle is the major pumping chamber on the lower left side of the heart that ejects blood into the systemic circuit via the aorta and receives blood from the left atrium; the right ventricle is the major pumping chamber on the lower right side of the heart that ejects blood into the pulmonary circuit via the pulmonary trunk and receives blood from the right atrium

    venule small vessel leading from the capillaries to veins

    white blood cells (WBCs) (also, leukocytes) one of the formed elements of blood that provides defense against disease agents and foreign materials

    Contributors and Attributions

    CC licensed content, Shared previously
    • Chapter 11. Authored by: OpenStax College. Provided by: Rice University. Located at: openstaxcollege.org/files/textbook_version/low_res_pdf/13/col11496-lr.pdf. Project: AtD Course. License: CC BY: Attribution

    9.6: Glossary- The Circulatory System is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

    • Was this article helpful?