Test 5 A&P

Pericardium

A double-layered sac (fibrous + serous) that encloses the heart and holds it in place.

Endocardium

The smooth, innermost layer lining the heart’s chambers and valves.

Myocardium

The thick, middle muscular layer of the heart wall responsible for pumping action.

Epicardium

The thin, outermost layer of the heart wall; also the visceral layer of the serous pericardium.

Mediastinum

The central compartment of the thoracic cavity where the heart is located.

Atrium

An upper receiving chamber of the heart (right or left).

Ventricle

A lower pumping chamber of the heart (right or left).

Septum

A wall that divides the right and left sides of the heart.

Valve

A flap-like structure that ensures one-way blood flow through the heart.

Tricuspid Valve

The right atrioventricular valve with three cusps; prevents backflow into the right atrium.

Bicuspid (Mitral) Valve

The left atrioventricular valve with two cusps; prevents backflow into the left atrium.

Pulmonary Valve

Semilunar valve at the exit of the right ventricle leading to the pulmonary trunk.

Aortic Valve

Semilunar valve at the exit of the left ventricle leading to the aorta.

Systole

The contraction phase of the cardiac cycle.

Diastole

The relaxation phase of the cardiac cycle.

Cardiac Cycle

One complete sequence of heart contraction (systole) and relaxation (diastole).

Stroke Volume (SV)

The amount of blood pumped by a ventricle in one heartbeat.

Heart Rate (HR)

The number of heartbeats per minute.

Cardiac Output (CO)

Volume of blood pumped by the heart per minute (CO = SV × HR).

Sinoatrial (SA) Node

Natural pacemaker located in the right atrium that initiates heartbeats.

Atrioventricular (AV) Node

Conduction node that delays impulses before they pass to the ventricles.

Bundle of His (AV Bundle)

Conduction fibers that carry impulses from the AV node to bundle branches.

Purkinje Fibers

Terminal conduction fibers that spread impulses through ventricular muscle.

Arrhythmia

Any abnormality of heart rhythm.

Bradycardia

A resting heart rate below 60 beats per minute.

Tachycardia

A resting heart rate above 100 beats per minute.

Sinus Arrhythmia

Normal, cyclic variation in heart rate associated with breathing.

Fibrillation

Rapid, uncoordinated contractions of heart muscle fibers.

Premature Ventricular Contraction (PVC)

An extra heartbeat initiated by Purkinje fibers.

Ischemia

Reduced blood supply to a tissue causing oxygen shortage.

Angina Pectoris

Chest pain caused by moderate myocardial ischemia.

Myocardial Infarction

Death of heart muscle cells from prolonged ischemia; a “heart attack.”

Infarct

An area of tissue death resulting from loss of blood supply.

Atherosclerosis

Hardening and narrowing of arteries due to cholesterol-rich plaque deposits.

Plaque

Fatty, cholesterol-laden deposit that builds up on arterial walls.

Coronary Thrombosis

Formation of a blood clot within a coronary artery.

Coronary Artery Disease (CAD)

Disease involving atherosclerotic narrowing of the coronary arteries.

Congestive Heart Failure

Inability of the heart to pump enough blood; leads to venous congestion and edema.

Murmur

Abnormal heart sound usually caused by faulty valves.

Organic Murmur

Pathologic heart sound produced by structural heart disease.

Functional Murmur

Normal or innocent extra heart sound heard during vigorous activity.

Pacemaker (Artificial)

Implanted device that electrically stimulates the heart to maintain rhythm.

Implantable Cardioverter-Defibrillator (ICD)

Device that detects and corrects life-threatening arrhythmias by shocking the heart.

Angiography

X-ray imaging of blood vessels after injection of a contrast dye.

Coronary Computed Tomography Angiography (CTA)

CT scan technique that visualizes coronary arteries with contrast dye.

Echocardiography

Ultrasound imaging that visualizes heart structure and function.

Electrocardiograph (ECG/EKG)

Instrument that records the electrical activity of the heart.

Stethoscope

Instrument used to listen to internal body sounds, including heartbeats.

Catheterization

Diagnostic or therapeutic procedure using a thin tube threaded through a vessel.

Coronary Artery Bypass Graft (CABG)

Surgical grafting of vessels to bypass blocked coronary arteries.

Angioplasty

Balloon procedure that widens narrowed coronary arteries.

Beta-Adrenergic Blocking Agent

Medication that lowers heart rate and cardiac output by inhibiting sympathetic effects.

Digitalis

Drug that increases cardiac contraction strength and slows heart rate.

Thrombolytic Drug

Medication that dissolves blood clots during myocardial infarction treatment.

Statin

Drug class that lowers blood cholesterol to slow atherosclerosis progression.

Intercalated Discs

Specialized junctions between cardiac muscle cells that allow rapid electrical conduction.

Pulmonary Circuit

Heart-lung pathway that carries blood from the right ventricle to the lungs and back to the left atrium.

Systemic Circuit

Pathway that carries oxygen-rich blood from the left ventricle to tissues and returns oxygen-poor blood to the right atrium.

Artery

Thick-walled vessel that carries blood away from the heart.

Arteriole

Small arterial subdivision that delivers blood to capillaries and helps regulate blood pressure by vasoconstriction or vasodilation.

Capillary

Microscopic, very thin-walled vessel where exchange of gases, nutrients, and wastes occurs between blood and tissues.

Venule

Smallest vein formed by the union of capillaries; carries blood toward larger veins.

Vein

Thin-walled vessel that returns blood to the heart; many contain valves.

Aorta

Largest artery; receives blood from the left ventricle and branches to supply the entire systemic circuit.

Pulmonary Circuit

Route of blood from the right ventricle through the lungs and back to the left atrium.

Systemic Circuit

Route of blood from the left ventricle through body tissues and back to the right atrium.

Anastomosis

A communication between two vessels that provides alternate pathways for blood flow (e.g., circle of Willis).

Endothelium

Simple squamous epithelial lining of blood vessels; forms the inner tunic.

Tunics

The three layers (inner endothelium, middle smooth muscle, outer connective tissue) that make up vessel walls.

Compliance

Ability of a blood vessel to expand to accommodate increased blood volume.

Elasticity

Ability of a vessel to return to its original size after being stretched.

Vasoconstriction

Narrowing of a blood vessel due to contraction of smooth muscle in the wall.

Vasodilation

Widening of a blood vessel due to relaxation of smooth muscle.

Bulk Flow

Movement of fluid and dissolved substances down a pressure gradient across the capillary wall.

Diffusion

Movement of individual solutes down their concentration gradients across capillary walls.

Filtration

Bulk flow of fluid from blood to interstitial fluid when capillary blood pressure exceeds osmotic pressure.

Absorption

Bulk flow of fluid from interstitial fluid into blood when osmotic pressure exceeds capillary blood pressure.

Blood Pressure

Force exerted by blood against vessel walls; normally measured in the brachial artery.

Systolic Pressure

Maximum arterial pressure occurring during ventricular contraction (~120 mm Hg).

Diastolic Pressure

Minimum arterial pressure occurring during ventricular relaxation (~80 mm Hg).

Pulse

Rhythmic pressure wave that travels through arteries with each left-ventricular contraction.

Baroreceptor

Pressure sensor in the aorta and carotid arteries that helps regulate blood pressure via negative feedback.

Sphygmomanometer

Instrument (blood-pressure cuff and gauge) used to measure arterial blood pressure.

Arteriosclerosis

General term for hardening and loss of elasticity of arteries.

Aneurysm

Abnormal, localized bulging sac in a vessel wall due to weakness.

Hemorrhage

Profuse bleeding from a ruptured blood vessel.

Shock

Failure of the circulatory system to deliver adequate oxygen to tissues; includes cardiogenic, septic, hypovolemic, and anaphylactic types.

Thrombosis

Formation of a stationary blood clot within a vessel.

Embolus

A clot or other material that travels through the bloodstream and may lodge in a vessel.

Phlebitis

Inflammation of a vein, often associated with clot formation.

Varicose Vein

Twisted, enlarged superficial vein resulting from valve failure.

Venous Sinus

Large channel that drains oxygen-poor blood, such as the coronary sinus of the heart or cranial dural sinuses.

Sinusoid

Wide, leaky capillary found in organs like the liver and bone marrow.

Hepatic Portal System

Venous network that carries nutrient-rich blood from digestive organs to liver sinusoids for processing.

Hepatic Portal Vein

Main vessel of the portal system formed chiefly by the superior mesenteric and splenic veins.

Superficial Vein

Vein located near the body surface that does not accompany an artery (e.g., cephalic, great saphenous).

Deep Vein

Vein that runs alongside a corresponding artery (e.g., femoral, brachial).

Vena Cava

Either of the two large veins (superior and inferior) that return systemic blood to the right atrium.

Coronary Sinus

Venous sinus on the posterior heart that drains cardiac muscle into the right atrium.

Azygos Vein

Unpaired vein that drains the thoracic wall into the superior vena cava.