Heart

• Mammals, including humans


  • Have a double circulatory system
  • Oxygenated blood is pumped from the heart to the lungs for oxygenation and then circulated to the rest of the body
  • This system ensures efficient oxygen delivery to tissues
• Human heart


  Consists of four chambers: two atria (upper chambers) and two ventricles (lower chambers)
• Atria


  • Have thin muscular walls
• Ventricles


  • Have thick muscular walls
• Atrioventricular (AV) valves


  Separate the atria from the ventricles
• Left AV valve


  Bicuspid valve
• Right AV valve


  Tricuspid valve
• The heart's right and left sides are completely separated by a septum, preventing blood mixing between them
• Blood vessels connected to the heart

  • Vena cava (superior and inferior)
  • Pulmonary artery
  • Pulmonary vein
  • Aorta
• Blood flow through the heart

  1. Deoxygenated blood enters the right atrium through the vena cava

  2. Flows to the right ventricle

  3. Pumped to the lungs via the pulmonary artery for oxygenation

  4. Oxygenated blood returns to the heart through the pulmonary vein into the left atrium

  5. Passes into the left ventricle

  6. Pumped out to the body via the aorta
• Both sides of the heart contract simultaneously to pump blood efficiently
• Left ventricle


  • Has a thicker muscular wall than the right ventricle
  • Pumps oxygenated blood to the entire body
• Right ventricle


  • Only pumps blood to the lungs
• The heart's major blood vessels, including the pulmonary artery and aorta, contain valves that prevent backflow of blood
• The coronary artery, branching directly from the aorta, supplies the heart muscle with oxygen and nutrients