Chapter 18: Heart Anatomy and Physiology Flashcards

Comprehensive vocabulary flashcards covering heart anatomy, circulation circuits, the intrinsic conduction system, the cardiac cycle, and regulation of cardiac output.

Pulmonary circuit

The right side of the heart that receives oxygen-poor blood from body tissues and pumps it to the lungs to release $CO_2$ and pick up $O_2$.

Systemic circuit

The left side of the heart that receives oxygenated blood from the lungs and pumps it out to the body to supply oxygen to tissues.

Atria

The two receiving chambers of the heart, located on the right and left sides.

Ventricles

The two pumping or discharging chambers of the heart, located on the right and left sides.

Mediastinum

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

Pericardium

A double-walled sac enclosing the heart, consisting of a fibrous layer and a serous layer.

Epicardium

The visceral layer of the serous pericardium that covers the external surface of the heart.

Pericardial cavity

The space between the visceral and parietal layers of the serous pericardium containing lubricating serous fluid.

Myocardium

The middle layer of the heart wall, composed mainly of cardiac muscle, forming the bulk of the heart.

Cardiac skeleton

A network of connective tissue fibers that reinforces the myocardium, supports heart valves, and provides electrical insulation.

Endocardium

The inner lining of the heart chambers, continuous with the endothelial linings of the vascular system.

Interatrial septum

The longitudinal partition that divides the right and left atria.

Interventricular septum

The longitudinal partition that lies between the right and left ventricles.

Coronary sinus

One of the three veins entering the right atrium, specifically returning blood from the myocardium.

Atrioventricular (AV) valves

Valves located between the atria and ventricles; include the tricuspid valve on the right and the mitral valve on the left.

Chordae tendineae

Collagen strings that anchor atrioventricular valve flaps to papillary muscles, preventing eversion of the valves into the atria.

Semilunar (SL) valves

The aortic and pulmonary valves found at the base of the large arteries exiting the heart, preventing backflow into the ventricles.

Coronary circulation

A series of vessels that exist to supply blood, oxygen, and nourishment to the heart muscle itself.

Intercalated discs

Connecting junctions between cardiac muscle cells containing desmosomes for structural strength and gap junctions for electrical communication.

Functional syncytium

A property of cardiac muscle where all fibers contract as a single unit due to electrical coupling via gap junctions.

Sinoatrial (SA) node

Located in the right atrium, this node serves as the intrinsic pacemaker for the heart.

Atrioventricular (AV) bundle

The only electrical connection between the atria and the ventricles, conducting impulses from the AV node.

Subendocardial conducting network

Also known as Purkinje fibers, it penetrates the ventricular walls to distribute impulses for contraction.

P wave

The first deflection of a typical ECG, indicating the depolarization of the atria.

QRS complex

The deflection on an ECG resulting from ventricular depolarization and atrial repolarization.

T wave

The deflection on an ECG caused by ventricular repolarization.

Systole

The contractile phase of the cardiac cycle.

Diastole

The relaxation phase of the cardiac cycle.

Cardiac output

The amount of blood pumped out of a ventricle per minute, calculated as the product of stroke volume and heart rate.

Stroke volume

The volume of blood pumped out of a ventricle per beat, which is roughly equal to $70\,\text{ml}$ in an average adult.

Frank-Starling law of the heart

The principle stating that the critical factor controlling stroke volume is preload, or the degree of stretch of cardiac muscle cells before they contract.

Afterload

The ventricular pressure that must be overcome before blood can be ejected from the heart.

Congestive heart failure

A condition occurring when the pumping efficiency of the heart is so low that blood circulation cannot meet tissue needs.