Introduction to the Heart and Cardiovascular System

Vocabulary-style flashcards covering the anatomy, superficial structures, internal chambers, conduction system, and physiological mechanisms of the human heart as presented in the lecture notes.

Cardiovascular system

A system composed of the heart, blood, and blood vessels.

Heart Daily Activity

The heart beats approximately $100,000$ times each day and pumps about $8000\,\text{liters}$ of blood per day.

Pulmonary circuit

A circulatory pathway that moves blood between the heart and lungs to remove carbon dioxide and pick up oxygen.

Systemic circuit

A circulatory pathway that moves blood between the heart and all of the body tissues to deliver oxygen and nutrients and remove wastes.

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that return blood to the heart.

Capillaries

Exchange vessels that interconnect the smallest arteries and smallest veins to exchange dissolved gases, nutrients, and wastes.

Right atrium

A heart chamber that receives deoxygenated blood from the systemic circuit.

Right ventricle

A heart chamber that pumps deoxygenated blood into the pulmonary circuit.

Left atrium

A heart chamber that receives oxygenated blood from the pulmonary circuit.

Left ventricle

A heart chamber that pumps oxygenated blood into the systemic circuit.

Base of the heart

The superior aspect of the heart where the great vessels connect.

Apex of the heart

The pointed, inferior tip of the heart located at the level of the $5^{th}$ intercostal space (specifically between the $4^{th}$ and $5^{th}$ rib space).

Fibrous pericardium

Tough connective tissue that attaches the heart to adjacent structures in the chest.

Serous pericardium

A thin, double-layered sac consisting of the visceral pericardium (on the heart) and the parietal pericardium (lining the pericardial cavity).

Pericardial cavity

The space between the visceral and parietal pericardium containing serous fluid which reduces friction.

Epicardium

The outer layer of the heart wall, which is also the visceral layer of the serous pericardium.

Myocardium

The muscular middle layer of the heart consisting of concentric layers of cardiac muscle tissue.

Endocardium

The inner layer of the heart wall lined by simple squamous epithelium.

Auricle

A medially located, expandable pouch associated with an atrium.

Coronary sulcus

A superficial groove that divides the atria and the ventricles.

Interventricular sulci

Grooves (anterior and posterior) that separate the left and right ventricles and contain blood vessels.

Septa

Muscular partitions that separate the chambers of the heart; include the interatrial septum and the interventricular septum.

Foramen ovale

An opening through the interatrial septum in the fetal heart that connects the two atria and closes at birth to form the fossa ovalis.

Pectinate muscles

Prominent muscular ridges on the anterior atrial wall and the inner surface of the auricle.

Tricuspid valve

The right atrioventricular (AV) valve with three cusps, located between the right atrium and right ventricle.

Chordae tendineae

Tendinous fibers that attach the free edges of AV valve cusps to the papillary muscles of the ventricle.

Trabeculae carneae

Muscular ridges located on the internal surface of both ventricles.

Moderator band

A muscular ridge in the right ventricle that delivers the electrical signal to the papillary muscles.

Conus arteriosus

The superior end of the right ventricle leading to the pulmonary valve.

Mitral valve

Also known as the Left AV valve or Bicuspid valve; it has two cusps and is located between the left atrium and left ventricle.

Coronary circulation

The blood supply to the muscle tissue of the heart, including coronary arteries emerging from the ascending aorta and cardiac veins.

Anastomoses

Interconnections between arteries, such as those between the anterior and posterior interventricular arteries, to maintain a constant blood supply.

Coronary sinus

A large vein where most cardiac veins drain blood before it empties into the right atrium.

Cardiac Conduction System

A specialized network of modified cardiac muscle cells responsible for generating and conducting electrical impulses to coordinate heart contraction.

Sinoatrial (SA) Node

The primary pacemaker of the heart located in the superior portion of the right atrium; it initiates each heartbeat.

Atrioventricular (AV) node

An electrical connection between the atria and ventricles that delays the impulse by approximately $0.10\,\text{sec}$ to allow for complete atrial contraction.

Purkinje Fibers

Fibers that rapidly distribute electrical impulses throughout the ventricular myocardium to trigger coordinated contraction.

Intercalated discs

Structures connecting branched cardiac muscle cells that contain desmosomes (for structural support) and gap junctions (for electrical communication).

Autorhythmic Cells

Also called Pacemaker Cells; they generate spontaneous electrical impulses and set the heart rhythm.

P wave

An ECG feature representing atrial depolarization.

QRS complex

An ECG feature representing ventricular depolarization.

T wave

An ECG feature representing ventricular repolarization.

Automaticity

The property of cardiac muscle tissue to contract automatically on its own without neural or hormonal control.

Systole

The phase of the cardiac cycle representing contraction of the heart chambers.

Diastole

The phase of the cardiac cycle representing relaxation of the heart chambers.

End-diastolic volume (EDV)

The maximum blood volume in the ventricles at the end of atrial systole.

Stroke volume (SV)

The amount of blood ejected by a ventricle during a single contraction; typically calculated as $SV = EDV - ESV$.

Cardiac output (CO)

The volume of blood pumped by the left ventricle in one minute; calculated as $CO = HR \times SV$.

Cardioacceleratory center

A center in the medulla that controls sympathetic neurons to increase heart rate.

Cardioinhibitory center

A center in the medulla that controls parasympathetic neurons via the Vagus nerve (CN X) to decrease heart rate.

Atrial reflex (Bainbridge reflex)

A reflex triggered by the stretching of the right atrial walls due to increased venous return, causing an increase in heart rate.

Frank-Starling law

The principle stating that as EDV increases, stroke volume increases due to the increased stretch and force of contraction.

Preload

The degree of ventricular stretching during ventricular diastole.

Afterload

The pressure the ventricles must overcome to eject blood, primarily determined by arterial blood pressure and vascular resistance.