Heart Structure and Function

Heart Structure and Function

• Superior vena cava and inferior vena cava: Two vessels returning blood to the right atrium.
• Pulmonary veins: Carry blood from the lungs to the left atrium.
• Right ventricle: Thinner-walled than the left ventricle.
• Pericardium: Encases the heart, protecting it from trauma and infection. Parts include parietal, visceral, and pericardial fluid.
• Heart layers: Epicardium (outermost), myocardium (middle, thickest, muscle layer), endocardium (inner lining).
• Endocardium: Inner lining of the heart wall, made of endothelium and connective tissue.
• Fibrous pericardium: Tough outer connective tissue sheath surrounding the heart.
• Parietal pericardium: Inner lining of the fibrous pericardium.
• Serous pericardium/fluid: Reduces friction between the outer surface of the heart and the pericardium.
• Heart valves: Control blood flow from one heart chamber to another, preventing backflow.
• Heart chambers: Right atrium receives deoxygenated blood from the superior and inferior vena cava; right ventricle receives and pumps blood to the lungs via the pulmonary artery; left atrium receives oxygenated blood from pulmonary veins; left ventricle receives and pumps blood to the rest of the body via the aorta.
• Semilunar valves: Prevent backflow into the ventricles during relaxation. These include: Pulmonary semilunar valve, Aortic semilunar valve.
• Atrioventricular (AV) valves: Prevent backflow into the atria during ventricular contraction. Includes Tricuspid and Bicuspid/Mitral valves.

Heart Valves

• Semilunar valves: Pulmonary and Aortic semilunar valves prevent backflow into ventricles during ventricular relaxation.
• Atrioventricular (AV) valves: Prevent backflow into atria during ventricular contraction including bicuspid/mitral & tricuspid valves.

Heart Wall Components

• Myocardium: Thickest layer, composed mainly of cardiac muscle.
• Epicardium: Outermost layer composed of epithelial and connective tissue, often called serous pericardium.
• Endocardium: Innermost layer lining the heart chambers and valves composed of endothelium and connective tissues.

Additional Heart Features

• Interventricular septum: Wall separating the two ventricles.
• Right atrium: Thin wall; fossa ovalis (medial wall depression) present in the fetal heart.
• Foramen ovale: Thin oval depression in the atrial wall (fetal heart), allowing blood flow from the right to the left atrium.
• Chordae tendinae: Thin, tough thread-like cords attaching to papillary muscles (extensions from the ventricle wall).
• Trabeculae carneae: Small extensions of the right ventricle wall.
• Right atrioventricular valve (tricuspid valve): Prevents backflow of blood from the right ventricle into the right atrium during ventricular contraction.