Cardiovascular system the Heart

Cardiovascular system

The circulatory transport system consisting of the heart, blood vessels, and blood.

Heart

The pump at the center of the circulatory system that moves blood through the pulmonary and systemic circuits.

Right heart

The right side of the heart that pumps blood through the pulmonary circuit to the lungs.

Left heart

The left side of the heart that pumps blood through the systemic circuit to the body.

Pulmonary circuit

The circuit from the right heart to the lungs and back to the heart; it carries blood for gas exchange.

Systemic circuit

The circuit from the left heart to the body and back to the heart; it supplies all body organs.

Pulmonary circuit pressure

A lower-pressure circuit compared with the systemic circuit.

Systemic circuit pressure

A higher-pressure circuit compared with the pulmonary circuit.

Mediastinum

The region between the lungs where the heart is located.

Base of heart

The broad superior portion of the heart.

Apex of heart

The inferior end of the heart that tilts left and tapers to a point.

Pericardium

A double-layered sac surrounding the heart that reduces friction, allows expansion, and limits excessive expansion.

Parietal pericardium

The outer, tough, fibrous connective-tissue layer of the pericardium.

Visceral pericardium

The inner, thin, smooth, moist serous layer covering the heart surface; also called the epicardium.

Epicardium

The visceral pericardium; the serous membrane covering the heart.

Pericardial cavity

The space between the parietal and visceral pericardium containing pericardial fluid.

Pericardial fluid

Fluid in the pericardial cavity that allows the heart to beat with reduced friction.

Heart wall

The three layers consisting of the epicardium, myocardium, and endocardium.

Myocardium

The thick muscular layer of the heart responsible for contraction.

Fibrous skeleton of heart

A network of collagenous and elastic fibers supporting cardiac muscle and providing attachment.

Electrical role of fibrous skeleton

The fibrous skeleton acts as an electrical nonconductor, helping coordinate cardiac contraction.

Endocardium

The smooth inner lining of the heart consisting of endothelium and areolar connective tissue.

Cardiac muscle cells

Short, branched cells with one central nucleus and large T-tubules.

Cardiac T-tubules

Large T-tubules that allow more Ca2+ to enter cardiac muscle cells from extracellular fluid.

Intercalated discs

Structures that join cardiac myocytes end-to-end.

Mechanical junctions

Connections in intercalated discs that tightly join adjacent cardiac myocytes.

Fascia adherens

Mechanical junction where actin is anchored to the plasma membrane and transmembrane proteins link cardiac cells.

Desmosomes

Mechanical junctions that strongly hold adjacent cardiac muscle cells together.

Gap junctions

Electrical junctions that allow ions to flow between cardiac muscle cells.

Cardiac muscle metabolism

Cardiac muscle relies almost exclusively on aerobic respiration.

Cardiac myoglobin

A protein abundant in cardiac muscle that supports aerobic metabolism.

Cardiac mitochondria

Cardiac muscle contains many large mitochondria to support its high aerobic energy demand.

Cardiac muscle fuel at rest

Fatty acids provide about 60%, glucose about 35%, and other fuels about 2%.

Cardiac muscle fatigue resistance

Cardiac muscle is fatigue resistant because it relies heavily on aerobic respiration and has little anaerobic fermentation.

Heart chambers

The four chambers are the right atrium, left atrium, right ventricle, and left ventricle.

Right atrium

A superior chamber that receives blood returning to the heart.

Left atrium

A superior chamber that receives blood returning to the heart.

Right ventricle

An inferior chamber that pumps blood into the pulmonary trunk.

Left ventricle

An inferior chamber that pumps blood into the aorta.

Atria

The two superior chambers that receive blood returning to the heart.

Ventricles

The two inferior chambers that pump blood into arteries.

Atrioventricular valves

Valves between the atria and ventricles that control blood flow between these chambers.

Right AV valve

The tricuspid valve; it has three cusps.

Tricuspid valve

The right AV valve with three cusps.

Left AV valve

The mitral or bicuspid valve; it has two cusps.

Mitral valve

The left AV valve, also called the bicuspid valve.

Bicuspid valve

The left AV valve with two cusps.

Chordae tendineae

Cords connecting AV valves to papillary muscles.

Papillary muscles

Muscles on the floor of the ventricles connected to the AV valves by chordae tendineae.

Semilunar valves

Valves that control blood flow from the ventricles into the great arteries.