Cardiology Terms

Endocardium

(Inner layer) Contains branches of the hearts electrical conduction system

Myocardium

(Middle layer) Made up of layers and bands of cardiac muscle fibers

Epicardium

(Outer layer) Single layer of cells supported by connective tissues; contains nerves to the heart and coronary blood vessels.

Tricuspid Valve

AV valve between the right atrium and right ventricle that closes during contraction and opens during relaxation

Mitral (Bicuspid Valve)

AV valve between left atrium and left ventricle. Close during contraction and opens during relaxation.

Pulmonic Valve

SL valve between the right ventricle and the pulmonary artery. Opens during contraction and closes during relaxation

Aortic Valve

SL valve between the left ventricle and the aorta. Opens during contraction and closes during relaxation

Irritability

When a site along the conduction pathway becomes irritable it speeds up and over takes higher pacemaki g sites for control of the heart

Escape Mechanism

Normal pacemaker slows down or fails, and the next fastest pacemaker takes control of the heart

Sympathetic

Increases heart rate, conduction, and irritability. Affects the atria and the ventricles.

Parasympathetic

Decreases heart rate, conduction, and irritability. Affects only the atria

Hematopoiesis

The process of blood cell formation

Hematopoietic System

Contains blood and the organs involved with development and production of blood.

Myeloid Tissue

Type of hematopoietic tissue that is in the bone marrow and produces RBC, WBC, and blood platelets

Lymphoid Tissue

Type of hematopoietic tissue found in the lymph nodes, thymus, and spleen.

Blood Composition

55% plasma, 45% formed cellular elements (RBC, WBC, and platelets)

Plasma Composition

92% Water and 7% proteins (Albumins, Globulins, and Fibrinogen)

Albumins

The majority of plasma proteins. They control movement of water into and out of the circulation.

Globulins

Type of plasma protein. They are antibodies made by the liver.

Gamma Globins

Produced in the lymphatic system and act as antibodies in the immune system

Fibrinogen

Type of plasma protein that is used for blood clotting

Hemocytoblast

Type of stem cell in the circulatory system that can form RBC, WBC, or platelets

Erythropoiesis

The process of making RBC

Erythropoietin

Hormone produced by the kidneys that stimulates RBC production by stem cells in the bone marrow

Hematocrit

Measurement of relative percentage of blood cells in a given volume of blood

Diapedesis

WBC move through the wall of the capillary and out to the tissue wehre they are needed most

Granulocytes

WBC with secretory granules in its cytoplasm

Neutrophils

Most common kind of granulocyte. They circulate in blood to find and destroy bacteria and are a major component in the inflammatory response

Eosinophils

Released substance that damages or kills parasitic invaders and also mitigate allergic response

Basophils

Play a role in allergic and inflammatory response. Releases histamines which dialates blood vessels and heparin which inhibits blood clotting

Agranulocytes

WBC that lack secretory granules in their cytoplasm

T Lymphocytes

Formed in the thymus and work to rid the body of bacteria and viruses

B Lymphocytes (B cells)

Formed in bone marrow and works to rid the body of bacterial and viral organisms through the production of antibodies

Monocytes

Type of WBC that is one of the first lines of defense in the inflammatory response

Thromopoietin

Protein hormone related to erythropoietin that mainly controls the production of platelets

Tissue Thromboplastin

Chemical that stimulates blood clotting. Result of Extrinsic pathway

Extrinsic Pathway

A hemostasis pathway that is the result of damage to the tissues releasing clotting factors that react with other clotting factors and calcium to produce tissue thromboplastin

Intrinsic Pathway

Type of hemostasis pathway that is the result of damaged platelets releasing clotting factors that react with other clotting factors and calcium to produce platelet thromboplastin

Platelet thromboplatin

Chemical that stimulates blood clotting

Result of the Intrinsic Pathway

Thrombin

Active form of prothrombin. Result of tissue and platelet thromboplastin joining and turning prothrombin into thrombin

Fibrin

White insoluble protein that forms the matrix of a blood clot. Formed from fibrinogen.

Plasmin

Dissolves the fibrin fibers of a blood clot. Formed during the clot dissolving portion of coagulation from plasminogen

Rh Positive

Means a person has antigens found on their RBC

Rh Negative

Means a person does not have antigens found on their RBC

Pericardium

Thick membrane that surrounds the heart and anchors it to the mediastinum to prevent over distention

Atrioventricular Valves

“AV Valves” Separate the atria from the ventricles

Semilunar Valves

“SL Valves” Separate the ventricles and their associated great vessel

S1 Sound

Heard when AV valves close and makes a “lub” sound

S2 Sound

Heard when SL valves close and makes a “dub” sound

S3 Sound

Low pitched “da” sound heard 1/3 of the way through ventricle diastole. Caused by vibrations of the ventricle wall due to rapid filling

S4 Sound

Medium pitched “bla” sound heard right before the normal S1 sound. Caused by decreased stretching on the left ventricle or increased pressure in the atria

Murmurs

Abnormal whooshing sound heard over the heart indicating turbulent blood flow through the heart valves

Bruits

Abnormal whooshing sounds heard over a main blood vessel indicating turbulent blood through in that vessel

Cardiac Output

Amount of blood pumped by the ventricles in 1 minute. Normal is 5-6 L/min

Stroke Volume

Amount of blood pumped out of a ventricle in one contraction. Normal is 60-100 mL

Preload

Volume of blood in the ventricles at the end of diastole

Afterload

Force against which the ventricles must contract to eject blood

Frank-Starling Mechanism/Starlings Law

When cardiac muscle is stretched, it contracts with a greater force to a limit

Ejection Fraction

Percentage of blood that leaves the heart each time it contracts. Normally 55% - 70%

Contractility

Ability of the heart to vary the degree of contractions without changing the stretch of the muscle

Inotropic Effect

Effect on the contractility of muscle tissue, especially in cardiac muscle

Chronotropic Effect

Increasing the rate of contraction (Positive Chronotropic Effect) or decreasing the rate of contraction (Negative Chronotropic Effect)

Myocardiac Cells

Contain contractile filaments that slide together when electrically stimulated, causing the myocardial cell to contract

Pacemaker Cells

Responsible for spontaneously generating and conducting electrical impulses

Automaticity

The ability of pacemaker cells to create an electrical impulse without being stimulated by another source

Excitability

Ability of cardiac muscle cells to respond to a stimulus

Conductivity

Ability of a cardiac cell to receive a cardiac impulse and pass it on to adjoining cardiac cells

Contractility

Ability of myocardial cells to shorten in response to an impulse which results in contraction

Sinoatrial Node (SA)

Initiates impulses through the myocardium, stimulating contraction of cardiac muscle fibers

Atrioventricular Node (AV)

Delays impulses through the myocardium, stimulating contraction of cardiac muscle fibers

Bundle of His

Located in the upper interventricular septum and conducts electrical impulses from the AV junction to the right and left bundle branches

Purkinje Fibers

System of fibers in the ventricles that conducts the excitation impulse from the bundle branches to the myocardium

Microcirculation

Where nutrients and cellular waste products are exchanged between blood and tissue

Tunica Intima

Tunic’s smooth, thin, innermost layer

Tunica Media

Middle layer of the tunic. Composed of elastic tissues and smooth muscle cells making it the thickest layer

Tunica Adventitia

Outermost layer of the tunic. Composed of elastic and fibrous connective tissue

Vasa Vasorum

Extends from the tunica adventitia to the tunica media to provide blood supply to the vessel walls

Conducting Arteries

Large arteries that arise from the aorta and its main branches

Arterioles

Smallest of the arteries. Connects arteries to capillaries

Subclavian

Divides off of the brachiocephalic artery and distributes blood to the extremities

Common Carotid Arteries

Divides off of the brachiocephalic and transports blood to the head and neck

Internal Carotid Arteries

Branches off of the common carotid artery and supplies the brain with blood

External Carotid Arteries

Branches off the common carotid artery and supplies the face, nose, and mouth

Visceral Arteries

Supplies blood to thoracic organs

Parietal Arteries

Supplies blood to the throatic wall

Intercostal Arteries

Run across the ribs and branch into anterior and posterior intercostal arteries supplying the chest wall

Celiac Trunk

Supplies blood to the esophagus, stomach, duodenum, spleen, liver, and pancreas

Superior Mesenteric

Supplies blood to the pancreas, small intestine, and colon

Inferior Mesenteric

Supplies blood to the descending colon and rectum

Internal Iliac Arteries

Supply pelvis (rectum, vagina, uterus, and ovaries) with blood

External Iliac Arteries

Supplies lower extremities with blood (butt, pubic region, rectum, external genitalia, and proximal thigh)

Axillary vein

Formed by the major veins of the arm, the basilic and cephalic veins and drains into the subclavian vein

Hepatic Portal System

Carries blood from the digestive tract to the liver, then to the inferior cava

Great Saphenous Vein

Longest vein in the body. Drains foot, leg, and thigh

Capillaries

Form connection between arterioles and venules. Where gas, nutrients, and many more things are exchanged.

Metarterioles

Short, connecting venules that can either connect to capillaries or bypass them and go straight to the venules

Precapillary Sphincter

Regulates blood flow into the capillary beds

Vasomotion

Intermittent contraction and relaxation of arterioles, metarterioles, precapillary sphincters, and some small arteries

Hydrostatic Pressure

Generated by contraction of the heart, gravity, and other forces. Pushes water out of the vessels

Oncotic Pressure

Form of osmotic pressure exerted by proteins in the blood plasma that pulls water into the circulatory system