Cardiovascular System Lecture: Heart Anatomy, Conduction, and Circulation

Comprehensive practice flashcards defining essential anatomical, physiological, and clinical vocabulary related to the cardiovascular system, heart coverings, valves, conduction pathways, and hemodynamics.

Fibrous pericardium

The outermost protective layer of the coverings that surround the heart.

Parietal pericardium

The layer of the pericardium that folds back from the visceral layer and sits directly inside the fibrous pericardium.

Pericardial cavity

The fluid-filled space between the parietal and visceral pericardial layers containing serous fluid to reduce friction created by the beating heart.

Epicardium

The outermost layer of the heart wall, which is identical to the visceral pericardium.

Myocardium

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

Endocardium

The thin, innermost epithelial layer that lines the inner surface of the heart chambers.

Mediastinum

The central compartment of the thoracic cavity situated between the two lungs where the heart, major blood vessels, and esophagus are located.

Apex of the heart

The pointed, inferior portion of the heart directed inferiorly and toward the left side of the body.

Tricuspid valve

The right atrioventricular valve located between the right atrium and the right ventricle that prevents backflow of blood.

Mitral valve

The left atrioventricular valve (also called the bicuspid valve) located between the left atrium and the left ventricle.

Pulmonary valve

The semilunar valve situated between the right ventricle and the pulmonary trunk.

Aortic valve

The semilunar valve located between the left ventricle and the aorta.

Superior vena cava

A large systemic vein that drains low-oxygen blood from the upper extremities and upper body into the right atrium.

Inferior vena cava

A major vein originating in the pelvic region that drains low-oxygen blood from the lower extremities and abdomen into the right atrium.

Coronary sinus

A venous channel located on the posterior surface of the heart that returns deoxygenated venous blood from the myocardium into the right atrium.

Pulmonary arteries

Vessels branching from the pulmonary trunk that carry low-oxygenated blood away from the right side of the heart to the lungs, representing an exception to the rule that arteries carry oxygenated blood.

Pulmonary veins

Vessels that carry high-oxygenated blood from the lungs back to the left atrium of the heart, representing an exception to the rule that veins carry deoxygenated blood.

Pulmonary circulation

The circuit of blood flow extending from the right side of the heart to the lungs for gas exchange and back to the left side of the heart.

Systemic circuit

The circulation pathway transporting oxygenated blood pumped from the left ventricle through the aorta to the body tissues and returning deoxygenated blood back to the right atrium.

Sinoatrial (SA) node

The primary natural pacemaker of the heart located in the superior wall of the right atrium that initiates electrical impulses at approximately $60$ to $80\,\text{beats per minute}$.

Atrioventricular (AV) node

The secondary pacemaker located in the inferior right atrium that delays the electrical impulse before passing it to the ventricles; capable of maintaining $40$ to $60\,\text{beats per minute}$ if the SA node fails.

Purkinje fibers

Conduction fibers branching upward into ventricular myocardium that trigger coordinated ventricular contraction beginning at the apex and moving upward.

P wave

The deflection on an electrocardiogram (EKG) representing atrial depolarization, which leads to atrial contraction.

QRS complex

The large electrical spike on an electrocardiogram representing ventricular depolarization and contraction, which simultaneously masks atrial repolarization.

T wave

The deflection on an electrocardiogram representing ventricular repolarization, which leads to ventricular relaxation.

Bradycardia

A condition characterized by a slow resting heart rate, typically falling below $60\,\text{beats per minute}$.

Tachycardia

A condition characterized by an excessively rapid heart rate, generally exceeding $100\,\text{beats per minute}$.

Atrial fibrillation

Rapid, uncoordinated contractions of the atria where the chambers do not beat in synchrony.

Ventricular fibrillation

A life-threatening arrhythmia marked by rapid, chaotic, and uncoordinated ventricular contractions that prevent blood from being pumped out of the heart, requiring defibrillation.

Capillaries

Microscopic, single-cell-thick vessels composed of simple squamous epithelium where nutrient, waste, oxygen, and carbon dioxide diffusion occurs.

Varicose veins

Distended, twisted superficial veins resulting from failed or malfunctioning venous valves that permit the backward pooling of blood.

Systole

The phase of the cardiac cycle representing contraction of the heart muscle, specifically measured during ventricular contraction in blood pressure readings.

Diastole

The phase of the cardiac cycle representing relaxation of the heart chambers, corresponding to the lower number in a blood pressure reading.

Vasoconstriction

The narrowing or constriction of the muscular walls of blood vessels, which increases vascular resistance and elevates blood pressure.