Anatomy & Physiology - Chapter 19: The Circulatory System: Heart

Vocabulary flashcards for key terms related to the heart and circulatory system from the lecture notes.

Cardiovascular system

Heart and blood vessels.

Circulatory system

Heart, blood vessels, and the blood.

Pulmonary circuit

Right side of heart, carries blood to lungs for gas exchange and back to heart.

Systemic circuit

Left side of heart, supplies oxygenated blood to all tissues of the body and returns it to the heart.

Base of heart

Wide, superior portion of heart, large vessels attach here.

Apex of heart

Tapered inferior end of the heart, tilts to the left.

Pericardium

Double-walled sac that encloses the heart, allows heart to beat without friction, provides room to expand, yet resists excessive expansion, anchored to diaphragm inferiorly and sternum anteriorly.

Fibrous pericardium

Outer wall of the pericardium, not attached to heart.

Parietal layer (of serous pericardium)

Lines fibrous pericardium.

Visceral layer (of serous pericardium)

Covers the heart surface (also known as the epicardium).

Pericardial cavity

Space between parietal and visceral layers of serous pericardium, filled with 5 to 30 mL of pericardial fluid.

Pericarditis

Painful inflammation of the membranes of the heart.

Epicardium

Serous membrane covering heart; adipose in thick layer in some places; coronary blood vessels travel through this layer.

Endocardium

Smooth inner lining of heart and blood vessels; covers the valve surfaces and is continuous with the endothelium of blood vessels.

Myocardium

Layer of cardiac muscle proportional to workload; muscle spirals around heart which produces wringing motion.

Fibrous skeleton of the heart

Framework of collagenous and elastic fibers; provides structural support, attachment for cardiac muscle and anchor for valve tissue and electrical insulation between atria and ventricles.

Atria (right and left)

Two superior chambers of the heart, receive blood returning to heart.

Ventricles (right and left)

Two inferior chambers of the heart, pump blood into arteries.

Coronary sulcus

Separates atria and ventricles; contains coronary arteries.

Interventricular sulcus

Overlies the interventricular septum that divides the right ventricle from the left; contains coronary arteries.

Interatrial septum

Wall that separates atria.

Pectinate muscles

Internal ridges of myocardium in right atrium and both auricles.

Interventricular septum

Muscular wall that separates ventricles.

Trabeculae carneae

Internal ridges in both ventricles; may prevent ventricle walls from sticking together after contraction.

Atrioventricular (AV) valves

Control blood flow between atria and ventricles.

Chordae tendineae

Cords connect AV valves to papillary muscles on floor of ventricles; prevent AV valves from flipping or bulging into atria when ventricles contract.

Semilunar valves

Control flow into great arteries; open and close because of blood flow and pressure.

Coronary circulation

5% of blood pumped by heart is pumped to the heart itself through this to sustain its strenuous workload.

Anterior interventricular branch (LAD)

Left coronary artery branch; supplies blood to both ventricles and anterior two-thirds of the interventricular septum.

Circumflex branch of LCA

Passes around left side of heart in coronary sulcus; supplies left atrium and posterior wall of left ventricle.

Right coronary artery (RCA)

Supplies right atrium and sinuatrial node (pacemaker).

Angina pectoris

Chest pain from partial obstruction of coronary blood flow; caused by ischemia of cardiac muscle.

Myocardial infarction (MI)

Sudden death of a patch of myocardium resulting from long-term obstruction of coronary circulation.

Coronary sinus

Returns most coronary blood to right atrium; has 3 main inputs: great cardiac, posterior interventricular, and left marginal veins.

Cardiomyocytes

Striated, short, thick, branched cells, one central nucleus surrounded by light-staining mass of glycogen; repair of damage is almost entirely by fibrosis (scarring).

Intercalated discs

Join cardiomyocytes end to end.

Fascia adherens

Broad band in which the actin of the thin myofilaments is anchored to the plasma membrane

Desmosomes

Mechanical linkages that prevent contracting cardiomyocytes from being pulled apart from each other.

Electrical junctions (gap junctions)

Allow ions to flow between cells; can stimulate neighbors; entire myocardium of either two atria or two ventricles acts like single, unified cell.

Conduction system

Coordinates the heartbeat; composed of an internal pacemaker and nerve-like conduction pathways through myocardium.

Sinuatrial (SA) node

Modified cardiomyocytes; pacemaker initiates each heartbeat and determines heart rate; located in right atrium near base of superior vena cava.

Atrioventricular (AV) node

Located near the right AV valve at lower end of interatrial septum; electrical gateway to the ventricles.

Atrioventricular (AV) bundle (bundle of His)

Bundle forks into right and left bundle branches which pass through interventricular septum toward apex.

Subendothelial conducting networks

Nerve-like processes spread throughout ventricular myocardium; cardiomyocytes then pass signal from cell to cell through gap junctions.

Systole

Contraction.

Diastole

Relaxation.

Sinus rhythm

Normal heartbeat triggered by the SA node; adult at rest is typically 70 to 80 bpm.

Ectopic focus

A region of spontaneous firing other than the SA node.

Nodal rhythm

If SA node is damaged, heart rate is set by AV node, 40 to 50 bpm.

Pacemaker potential

Gradual depolarization of the SA node due to slow Na+ inflow.

Electrocardiogram (ECG or EKG)

Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs, and chest.

P wave

SA node fires, atria depolarize and contract; atrial systole begins 100 ms after SA signal.

PR interval

Signal conduction through AV node, before activating ventricles.

QRS complex

Ventricular depolarization; complex shape of spike due to different thickness and shape of the two ventricles.

QT interval

Duration of ventricular depolarization; shorter during exercise.

ST segment

Ventricular systole; corresponds to plateau in myocardial action potential.

T wave

Ventricular repolarization and relaxation.

Ventricular fibrillation

Serious arrhythmia caused by electrical signals traveling randomly; heart cannot pump blood; no coronary perfusion; hallmark of heart attack (MI).

Defibrillation

Strong electrical shock with intent to depolarize entire myocardium and reset heart to sinus rhythm.

Atrial fibrillation

Chaotic depolarizations that do not stimulate ventricles; common in elderly and alcoholics.

Heart block

Failure of any part of the cardiac conduction system to conduct signals, usually result of disease or degeneration of conduction system.

Premature ventricular contraction

Ventricular ectopic focus with extra beat; may result from stress, lack of sleep or stimulants.

Cardiac cycle

One complete contraction and relaxation of all four chambers of the heart.

Valvular insufficiency (incompetence)

Any failure of a valve to prevent reflux (regurgitation), the backward flow of blood.

Valvular stenosis

Cusps are stiffened and opening is constricted by scar tissue.

Heart murmur

Abnormal heart sound produced by regurgitation of blood through incompetent valves.

Mitral valve prolapse

Insufficiency in which one or both mitral valve cusps bulge into atria during ventricular contraction.

Auscultation

Listening to sounds made by body

First heart sound (S1)

Loud and longer sound, occurs with closure of AV valves, turbulence in the bloodstream, and movements of the heart wall.

Second heart sound (S2)

Softer and sharper sound, occurs with closure of semilunar valves, turbulence in the bloodstream, and movements of the heart wall.

Cardiac output (CO)

Amount ejected by each ventricle in 1 minute.

Cardiac reserve

The difference between a person’s maximum and resting CO.

Pulse

Surge of pressure produced by heart beat that can be felt by palpating a superficial artery.

Tachycardia

Resting adult heart rate above 100 bpm.

Bradycardia

Resting adult heart rate of less than 60 bpm.

Positive chronotropic agents

Factors that raise the heart rate.

Negative chronotropic agents

Factors that lower the heart rate.

Cardiostimulatory effect

Some neurons of the cardiac center transmit signals to the heart by way of sympathetic pathways.

Cardioinhibitory effect

Others transmit parasympathetic signals by way of the vagus nerve.

Vagal tone

Holds down the heart rate to 70 to 80 bpm at rest, due to steady background firing rate of the vagus nerves.

Baroreflexes and chemoreflexes

Responses to fluctuation in blood pressure and chemistry that are both negative feedback loops.

Hyperkalemia

Excess K+ diffuses into cardiomyocytes.

Hypokalemia

Deficiency in K+.

Hypercalcemia

Excess of Ca2+.

Hypocalcemia

Deficiency of Ca2+.

Preload

Amount of tension in ventricular myocardium immediately before it begins to contract.

Frank–Starling law of the heart

SV ∝ EDV, Stroke volume is proportional to the end diastolic volume.

Contractility

Refers to how hard the myocardium contracts for a given preload.

Positive inotropic agents

Increase contractility.

Negative inotropic agents

Reduce contractility.

Afterload

Sum of all forces opposing ejection of blood from ventricle.

Cor pulmonale

Right ventricular failure due to obstructed pulmonary circulation.

Coronary artery disease (CAD)

A constriction of the coronary arteries.

Atherosclerosis

An accumulation of lipid deposits that degrade the arterial wall and obstruct the lumen.

Low-density lipoprotein (LDL)

protein-coated droplets of cholesterol, neutral fats, free fatty acids, and phospholipids.