2.4 chambers

• The heart has four chambers
• The upper two chambers are the atria
• The lower two are the ventricles
• The chambers are separated by a wall of tissue called the septum
• Blood is pumped through the chambers, aided by four heart valves
• The valves open and close to let the blood flow in only one direction
• The right atrium receives oxygen-poor (deoxygenated) blood from the body and pumps it to the right ventricle
• The right ventricle pumps the oxygen-poor blood to the lungs
• The left atrium receives oxygen-rich (oxygenated) blood from the lungs and pumps it to the left ventricle
• The left ventricle pumps the oxygen-rich blood to the body
• The interventricular septum is a muscular wall that separates the right and left ventricles
• The interatrial septum separates the right and left atria
• The atrium and ventricle on each side of the heart are separated by an atrioventricular (AV) valve.
• The right AV valve, or tricuspid valve, separates the right atrium and right ventricle
• The left AV valve, or bicuspid valve, separates the left ventricle and the left atrium. This valve is also called the mitral valve
• There are also two semilunar valves:

  • Pulmonary Valve
  • Aortic Valve
• The pulmonary valve separates the right ventricle from the pulmonary trunk
• The aortic valve separates the left ventricle from the aorta