Chapter 18

Heart Chambers

Four distinct sections of the heart: right atrium, left atrium, right ventricle, and left ventricle.

Pulmonary Circuit

Pathway in which the right side of the heart pumps oxygen-poor blood to the lungs.

Systemic Circuit

Pathway in which the left side of the heart pumps oxygenated blood to the body.

Pericardium

A double-walled sac surrounding the heart, providing protection and anchoring it to surrounding structures.

Pericarditis

An inflammation of the pericardium that can lead to pain and complications like cardiac tamponade.

Myocardium

The muscular layer of the heart, responsible for its contraction and pumping action.

Endocardium

The innermost layer of the heart, continuous with the endothelial lining of blood vessels.

Atrioventricular (AV) Valves

Valves located between the atria and ventricles that prevent backflow of blood.

Semilunar Valves

Valves located between the ventricles and their major arteries, preventing backflow into the heart.

Cardiac Output (CO)

The volume of blood pumped by each ventricle per minute, affected by heart rate and stroke volume.

Frank-Starling Law

The relationship between preload and stroke volume, stating that increased preload leads to increased stroke volume.

Ejection Fraction

The percentage of blood ejected from the ventricles during each contraction, indicating heart efficiency.

Pacemaker Cells

Specialized cardiac cells that initiate the action potential and set the heart rhythm.

Sinoatrial (SA) Node

The primary pacemaker of the heart that generates electrical impulses for the heartbeat.

Electrocardiogram (ECG/EKG)

A graphic representation of the heart's electrical activity, used to diagnose heart conditions.

Diastole

The phase of the cardiac cycle when the heart muscle relaxes and chambers fill with blood.

Systole

The phase of the cardiac cycle when the heart muscle contracts and pumps blood out of the chambers.

Arrhythmia

An irregular heartbeat resulting from defects in the cardiac conduction system.

Tachycardia

An abnormally fast heart rate, typically exceeding 100 beats per minute.

Bradycardia

An abnormally slow heart rate, typically fewer than 60 beats per minute.

Congestive Heart Failure (CHF)

A condition in which the heart fails to pump effectively, resulting in inadequate blood circulation.

Hypocalcemia

A condition of low calcium levels in the blood, potentially leading to depression of heart function.

Cardiac Tamponade

A medical emergency where excess fluid accumulates in the pericardial cavity, compressing the heart.

Atherosclerosis

A condition characterized by the buildup of fats, cholesterol, and other substances in and on artery walls.

Coronary Circulation

The circulation of blood in the blood vessels supplying the heart muscle.

Intercalated Discs

Specialized connections between cardiac muscle cells that enable synchronized contractions.

Dicrotic Notch

A small dip in arterial pressure following closure of the aortic valve indicating backflow of blood.

Stroke Volume (SV)

The amount of blood pumped by each ventricle with each heartbeat.

Afterload

The pressure that the ventricles must overcome to eject blood, influenced by arterial blood pressure.