The Cardiovascular System: The Heart Lecture Notes

A comprehensive set of vocabulary flashcards covering the anatomy, circulation, conduction system, cardiac cycle, and physiology of the heart based on Chapter 19.

Mediastinum

The anatomical region between the lungs where the heart is located.

Pericardial cavity

The specific body cavity that houses the heart.

Cardiac notch

The depression in the left lung that accommodates the heart.

Pulmonary circuit

The portion of the circulatory system that carries blood between the heart and the lungs.

Systemic circuit

The portion of the circulatory system that carries blood between the heart and the rest of the body.

Pulmonary artery

The only artery in the human body that carries deoxygenated blood.

Pulmonary vein

The only vein in the human body that carries oxygenated blood.

Fibrous pericardium

The outer layer of the pericardium made of dense connective tissue that protects and maintains the heart's position.

Myocardium

The middle, thickest layer of the heart wall composed of cardiac muscle cells arranged in complex swirling patterns.

Endocardium

The deepest layer of the heart wall that lines the chambers.

Fossa ovalis

A depression in the interatrial septum that was originally an opening called the foramen ovale during fetal development.

Atrioventricular (AV) valves

The valves that separate the atria from the ventricles, including the tricuspid and mitral (bicuspid) valves.

Semilunar valves

The valves that separate the ventricles from the great vessels, including the pulmonary and aortic valves.

Chordae tendineae

The string-like structures that connect the tricuspid and mitral valves to the papillary muscles.

Trabeculae carneae

The ridges of muscle found on the internal walls of the ventricles.

Moderator band

A muscular band found specifically in the right ventricle.

Autorhythmicity

The ability of specialized cardiac cells to initiate an electrical potential and set the contraction rate.

Intercalated disc

The structure that binds adjacent cardiac sarcolemma together and synchronizes muscular contraction.

Sinoatrial (SA) node

Known as the pacemaker, it initiates the sinus rhythm and action potentials in the heart.

Atrioventricular (AV) node

Located in the right atrium, it delays the electrical impulse by approximately $100\,ms$ to allow atria to finish contracting.

Purkinje cells

Specialized cells that spread the electrical impulse from the bundle branches to the myocardial contractile cells.

P wave

The part of an ECG tracing that represents the depolarization of the atria.

QRS complex

The part of an ECG tracing that represents the depolarization of the ventricles.

T wave

The part of an ECG tracing that represents the repolarization of the ventricles.

Systole

The phase of the cardiac cycle when the heart muscle is contracting.

Diastole

The phase of the cardiac cycle when the heart muscle is relaxing.

Isovolumic contraction

The phase of ventricular systole where pressure rises but no blood is yet ejected.

S1

The first heart sound heard during auscultation, caused by the closing of the atrioventricular valves.

S2

The second heart sound heard during auscultation, caused by the closing of the semilunar valves.

Cardiac Output (CO)

The total volume of blood pumped by the heart each minute, calculated as $CO = HR \times SV$.

Ejection Fraction

The portion of blood pumped out of a filled ventricle, with a normal range of $55-70\%$, calculated using stroke volume and end diastolic volume.

Cardioaccelerator center

The region in the medulla that stimulates the heart via sympathetic nerves to release norepinephrine and increase heart rate.

Cardioinhibitory center

The region in the medulla that sends signals via the vagus nerve (parasympathetic) to release acetylcholine and slow the heart rate.

Bainbridge reflex

Also known as the atrial reflex, it is a cardiac reflex that responds to changes in blood volume returning to the atria.

Preload

A factor affecting stroke volume related to filling time and venous return, which increases end diastolic volume.

Afterload

The vascular resistance or pressure that the heart must overcome to eject blood during systole.

Mesoderm

The embryonic tissue layer from which the heart begins to form approximately $18-19$ days after fertilization.