Heart Structure and Function Overview

Heart Structure and Function

• The heart is a double pump, functionally separated into two sides.
• Right Side: Receives deoxygenated blood from the body, pumps it to the lungs for oxygenation, and then removal of carbon dioxide. This is the pulmonary circuit.
• Left Side: Receives oxygenated blood from the lungs, pumps it to the body's tissues, and this is the systemic circuit.

Heart Chambers

• Atria: Receiving chambers with thin walls. They contribute little to blood propulsion.
  • Right Atrium: Receives blood from the systemic circuit (body).
  • Left Atrium: Receives blood from the pulmonary circuit (lungs).
• Ventricles: Pumping chambers with thicker walls. They constitute the bulk of the heart volume.
  • Right Ventricle: Pumps blood to the lungs (pulmonary circuit).
  • Left Ventricle: Pumps blood to the body (systemic circuit).

Heart Valves

• Valves prevent backflow of blood. Details on specific valves are not provided.

Heart Wall Layers

• Epicardium: The outer layer, also known as the visceral layer of the serous pericardium. Reduces friction.
• Myocardium: The middle layer, composed of cardiac muscle, responsible for the heart's pumping action. Cardiac muscle fibers are arranged in spiral and circular bundles.
• Endocardium: The inner layer, continuous with the endothelial lining of blood vessels. Lines heart chambers and valves.

Heart Coverings

• Pericardium: A double-walled sac surrounding the heart; reduces friction.
• Pericarditis: Inflammation of the pericardium characterized by a creaking sound (pericardial friction rub).
• Cardiac Tamponade: Excessive fluid in the pericardial sac, compressing the heart, potentially compromising its function. Treatment involves fluid removal.

Major Vessels

• Superior Vena Cava: Returns deoxygenated blood from the upper body to the right atrium.
• Inferior Vena Cava: Returns deoxygenated blood from the lower body to the right atrium.
• Coronary Sinus: Drains deoxygenated blood from the heart's own tissues into the right atrium.
• Pulmonary Veins: Four vessels returning oxygenated blood from the lungs to the left atrium (a unique feature; veins carrying oxygenated blood).

Septums

• Interatrial Septum: Separates the atria.
• Interventricular Septum: Separates the ventricles.

Ventricular Differences

• The left ventricle wall is thicker than the right ventricle wall because it pumps blood over a greater distance against higher pressure in the systemic circulation.

Papillary Muscles and Chordae Tendineae

• Papillary muscles project into the ventricular cavity, anchoring chordae tendineae which in turn attach to heart valves.