Heart Function in Blood Circulation

Heart Function in Blood Circulation

Heart Structure

• The heart is a muscular organ that pumps blood throughout the body
• Divided into four chambers: right atrium, left atrium, right ventricle, and left ventricle
• Septum separates the right and left sides of the heart

Heart Function

• The heart pumps blood through a process called cardiac cycle:
  1. Diastole: heart muscle relaxes, ventricles fill with blood
  2. Atrial contraction: atria contract, pumping blood into ventricles
  3. Ventricular contraction: ventricles contract, pumping blood out of the heart
  4. Isovolumic contraction: ventricles contract, but no blood leaves the heart
  5. Rapid ejection: blood is rapidly pumped out of the heart
  6. Reduced ejection: blood is slowly pumped out of the heart
  7. Isovolumic relaxation: ventricles relax, but no blood enters the heart

Blood Flow Through the Heart

• Deoxygenated blood enters the right atrium through the superior and inferior vena cavae
• Blood flows from the right atrium to the right ventricle through the tricuspid valve
• Blood is pumped from the right ventricle to the lungs through the pulmonary valve
• Oxygenated blood returns to the heart through the pulmonary veins and enters the left atrium
• Blood flows from the left atrium to the left ventricle through the mitral valve
• Blood is pumped from the left ventricle to the rest of the body through the aortic valve

Heartbeat Regulation

• The heartbeat is regulated by the autonomic nervous system
• The sinoatrial (SA) node, located in the right atrium, acts as the pacemaker of the heart
• The SA node generates an electrical signal that triggers the heartbeat
• The atrioventricular (AV) node, located between the atria and ventricles, relays the electrical signal to the ventricles