Anatomy and Physiology II: The Heart and Cardiovascular System

Vocabulary practice cards focusing on key structures, layers, vessels, electrical conduction elements, ECG phases, and neural regulation of the human heart based on lecture slides.

Circulatory Fluid (Blood)

The medium in the cardiovascular system where gases, nutrients, and wastes dissolve and/or are carried throughout the body.

Apex of the heart

The anatomical tip of the heart that is directed anteriorly, inferiorly, and to the left.

Base of the heart

The posterosuperior surface of the heart that is directed posteriorly, superiorly, and to the right.

Fibrous pericardium

The tough, flexible outer layer of the pericardium formed by dense, irregular connective tissue (collagen fibres) that protects, anchors, and prevents overstretching of the heart.

Serous pericardium

The inner double-layered membrane of the pericardium formed by mesothelium and loose connective tissue that reduces friction during cardiac contraction.

Pericardial cavity

The space located between the parietal layer and visceral layer (epicardium) of the serous pericardium containing pericardial fluid to reduce friction.

Epicardium

The visceral layer of the serous pericardium, which forms the outermost layer of the heart wall.

Myocardium

The middle muscular layer of the heart wall composed of cardiac muscle tissue responsible for pumping blood.

Endocardium

The innermost layer of the heart wall composed of epithelial tissue lining the interior of the heart chambers.

Atria

The two upper, thin-walled heart chambers that receive blood returning to the heart and pump it into the ventricles.

Ventricles

The two lower, thick-walled heart chambers responsible for pumping blood away from the heart into the lungs or body tissues.

Interventricular Septum

A muscular wall composed of myocardium that separates the right and left ventricles of the heart.

Superior Vena Cava

A large vein that returns deoxygenated blood from the upper systemic circuit back to the right atrium.

Inferior Vena Cava

A large vein that returns deoxygenated blood from the lower systemic circuit back to the right atrium.

Pulmonary Veins

Blood vessels that transport oxygenated blood from the lungs back into the left atrium of the heart.

Trunk (Blood Vessel)

A anatomical term for a large primary blood vessel that serves as a main stem before dividing into two or more major branches.

Pulmonary Trunk

The main arterial trunk exiting the right ventricle that carries deoxygenated blood and divides into the right and left pulmonary arteries.

Aorta

The main systemic artery exiting the left ventricle that carries oxygenated blood under high pressure to the entire body.

Atrioventricular (AV) Valves

Valves located between each atrium and ventricle that prevent the backflow of blood into the atria during ventricular contraction.

Tricuspid Valve

The right atrioventricular valve composed of three flaps of connective tissue located between the right atrium and right ventricle.

Bicuspid (Mitral) Valve

The left atrioventricular valve composed of two flaps of connective tissue located between the left atrium and left ventricle.

Semilunar Valves

Valves (aortic and pulmonary) located between the ventricles and the major exiting arteries that open during contraction and close during relaxation to prevent backflow into the ventricles.

Chordae Tendinae

Tendon-like fibrous cords anchoring the cusps of the atrioventricular valves to papillary muscles in the ventricle walls.

Papillary Muscles

Projections of myocardial muscle in the ventricular walls that contract to tighten chordae tendinae and prevent AV valve eversion.

Pulmonary Circuit

The circulatory route that carries deoxygenated blood from the right side of the heart to the lungs for gas exchange and returns oxygenated blood to the left atrium.

Systemic Circuit

The circulatory route that carries oxygenated blood from the left side of the heart to all body tissues and returns deoxygenated blood to the right atrium.

Coronary Circuit

A specialized loop of systemic circulation where coronary arteries branch from the aorta to supply oxygenated blood directly to the myocardium, draining into the coronary sinus.

Autorhythmic Fibres

Specialized cardiac muscle cells capable of spontaneously generating and conducting action potentials without direct nervous system stimulation.

Sinoatrial (SA) Node

A cluster of autorhythmic cells in the wall of the right atrium that acts as the primary pacemaker of the heart, initiating impulses at an intrinsic rate of ~$100\text{/min}$.

Atrioventricular (AV) Node

A cluster of autorhythmic cells in the interatrial septum that receives impulses from the SA node and delays electrical conduction by ~$0.1\text{ sec}$ to allow full atrial contraction.

Atrioventricular (AV) Bundle (Bundle of His)

A bundle of conducting fibres in the superior interventricular septum that forms the sole electrical connection between the atria and ventricles.

Purkinje Fibres

Large-diameter conducting fibres that spread rapidly from the heart apex upward through the ventricular myocardium, causing synchronized bottom-up ventricular contraction.

P Wave

The component of an ECG trace that represents the depolarization of atrial contractile fibres starting from the SA node.

Atrial Systole

The mechanical contraction phase of the atria triggered by atrial depolarization, which actively completes the filling of the ventricles.

QRS Complex

The large wave feature on an ECG trace representing the rapid depolarization of ventricular contractile fibres.

Ventricular Systole

The mechanical contraction phase of the ventricles triggered by depolarization, closing AV valves, opening semilunar valves, and ejecting blood into the pulmonary trunk and aorta.

T Wave

The deflection wave on an ECG trace that represents the repolarization of ventricular contractile fibres.

Ventricular Diastole

The relaxation phase of the ventricles during which intraventricular pressure falls, semilunar valves close, AV valves open, and ventricles begin refilling with blood.

Cardiac Accelerator Nerves

Sympathetic nerves originating from the cardiovascular center that increase the rate of spontaneous depolarization in the SA node and increase heart contractility.

Vagus Nerves (Cranial Nerve X)

Parasympathetic nerves originating from the cardiovascular center that decrease the rate of spontaneous depolarization in the SA node to lower heart rate.

Hyperkalemia

A severe elevation of potassium ($K^+$) levels in the blood that significantly slows heart rate, depresses contractility, and can cause cardiac arrest during diastole.