heart

(noun)

A fist-sized muscular organ in the chest that pumps blood through the body using involuntary contractions of cardiac muscle.

Related Terms

Examples of heart in the following topics:

  • Heart Failure

    • Heart failure is defined as the inability of the heart to supply blood to the organs of the body.
    • Heart failure (HF) often called congestive heart failure (CHF) is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body.
    • Common causes of heart failure include myocardial infarction and other forms of ischemic heart disease, hypertension, valvular heart disease, and cardiomyopathy.
    • The term "heart failure" is sometimes incorrectly used to describe other cardiac-related illnesses, such as myocardial infarction (heart attack) or cardiac arrest, which can cause heart failure but are not equivalent to heart failure.
    • Heart murmurs may indicate the presence of valvular heart disease, either as a cause (e.g. aortic stenosis) or as a result (e.g., mitral regurgitation) of the heart failure.

  • Anatomy of the Heart

    • The heart consists of four chambers separated into two sides.
    • Each side contains an atria which receives blood into the heart and flows it into a ventricle, which pumps the blood out of the heart.
    • The left heart deals with systemic circulation, while the right heart deals with pulmonary circulation.
    • The heart also has its own blood supply, the cardiac arteries that provide tissue oxygenation to the heart as the blood within the heart is not used for oxygenation by the heart.
    • This composite sac protects the heart, anchors it to surrounding structures, and prevents the heart from overfilling with blood.

  • Congenital Heart Defects

    • A congenital heart defect is a defect in the structure of the heart and great vessels that is present at birth.
    • Many types of heart defects exist, most of which either obstruct blood flow in the heart or vessels near it, or cause blood to flow through the heart in an abnormal pattern.
    • Congenital heart defects cause abnormal heart structure resulting in production of certain sounds called heart murmur.
    • It is called hypoplastic left heart syndrome when it affects the left side of the heart and hypoplastic right heart syndrome when it affects the right side of the heart.
    • Hypoplasia of the heart is generally a cyanotic heart defect.

  • Pumps and the Heart

    • The heart is made up of four chambers.
    • Two atria at the top of the heart receive blood and two ventricles at the bottom of the heart pump blood out of the heart.
    • A complete cardiac cycle is one round of the heart pumping blood and consists of two parts: systole (contraction of the heart muscle) and diastole (relaxation of the heart muscle).
    • During the cycle, the top half of the heart works as one unit, while the bottom half of the heart works as one unit.
    • The heart beat can be heard as a sound that the valves make when they close.

  • Layers of the Heart Walls

    • The outer layer of the heart wall is the epicardium.
    • The epicardium refers to both the outer layer of the heart and the inner layer of the serous visceral pericardium, which is attached to the outer wall of the heart.
    • The middle layer of the heart wall is the myocardium—the muscle tissue of the heart and the thickest layer of the heart wall.
    • This in turn can affect the contractility of the heart.
    • The dark area on the heart wall is scarring from a previous myocardial infarction (heart attack).

  • Fibrous Skeleton of the Heart

    • The cardiac skeleton, also known the heart's fibrous skeleton, consists of dense connective tissue in the heart that separates the atria from the ventricles.
    • The fibrous skeleton provides critical support for the heart and separates the flow of electrical impulses through the heart.
    • The fibrous skeleton of the heart acts as an insulator for the flow of electrical current across the heart.
    • This electrical separation is essential for cardiac function, because electrical impulses flow from the top of the heart to the bottom of the heart.
    • Without the fibrous skeleton of the heart, the heart's ability to pump blood would be considerably less efficient since the ventricles would contract before filled to capacity.

  • The Complement System and Heart Disease

    • Autoimmune heart diseases result when the body's own immune defense system mistakes cardiac antigens as foreign, and attacks them, leading to inflammation of the heart as a whole, or in parts.
    • The most common form of autoimmune heart disease is rheumatic heart disease, or rheumatic fever.
    • After healing, there may be fibrosis and adhesion of the pericardium with the heart, leading to constriction of the heart and reduced cardiac function.
    • Myocarditis: Here the muscle bulk of the heart gets inflamed.
    • Endocarditis: Here the inner lining of the heart is inflamed, including the heart valves.

  • Aging and the Heart

    • As a person ages, the walls of the heart thicken, the heart becomes heavier, valves stiffen and leak, and the aorta becomes larger.
    • As a person ages, the heart goes through certain structural changes: the walls of the heart thicken and the heart becomes heavier, heart valves stiffen and are more likely to calcify, and the aorta, the major vessel carrying blood out of the heart, becomes larger.
    • The heart muscle becomes less efficient with age, and there is a decrease in both maximum cardiac output and heart rate, although resting levels may be more than adequate.
    • A weak ventricle is not an efficient pump, and may progress to congestive heart failure.
    • The heart valves may become thickened by fibrosis or calcification, leading to heart murmurs and less efficient pumping.

  • Structures of the Heart

    • The heart is a complex muscle that pumps blood through the three divisions of the circulatory system: the coronary (vessels that serve the heart), pulmonary (heart and lungs), and systemic (systems of the body).
    • Coronary circulation intrinsic to the heart takes blood directly from the main artery (aorta) coming from the heart.
    • In humans, the heart is about the size of a clenched fist.
    • The myocardium consists of the heart muscle cells that make up the middle layer and the bulk of the heart wall.
    • The heart has its own blood vessels that supply the heart muscle with blood.

  • Congestive Heart Failure

    • Heart failure is a common, costly, disabling, and potentially deadly condition.
    • Heart failure is the leading cause of hospitalization in people older than 65.
    • Heart failure can result from any one, or combinations of, cardiomyopathies or problems within the heart muscle, and these problems can result in heart failure.
    • However, this also increases the amount of work the heart has to perform.
    • Common signs and symptoms of heart failure are depicted in the diagram.