Anatomy and Function of the Heart

General Structure

• The heart is a muscular organ, approximately the size of a fist.
• Located slightly left of center in the chest.
• Divided into right and left sides to prevent mixing of oxygen-rich and oxygen-poor blood.

Cardiovascular System

• Composed of the heart and blood vessels.
• Circulates blood and oxygen throughout the body.
• Heart pumps about five quarts of blood per minute.
• Beats approximately 100,000 times per day or 35 million times per year.

Blood Circulation

• Oxygen-poor blood (blue):
  • Returns to the heart after body circulation.
  • Collected in the right atrium and ventricle.
  • Pumped to the lungs via pulmonary arteries for oxygenation.
• Oxygen-rich blood (red):
  • Enters the left side of the heart (left atrium and ventricle).
  • Pumped through the aorta to supply the body’s tissues.

Heart Valves

• Four valves ensure unidirectional blood flow: tricuspid, mitral, pulmonary, and aortic.
• Valves function like gates, opening in one direction only.
• Each valve opens and closes once per heartbeat (roughly once every second).

Heartbeat Cycle

• Systole:
  • Ventricles contract to push blood into lungs and body (like squeezing ketchup from a bottle).
  • Right ventricle contracts slightly before the left.
• Diastole:
  • Ventricles relax and fill with blood from the atria.
  • Atria prepare for the next cycle.

Coronary Circulation

• Coronary arteries nourish the heart.
• Extend over the heart’s surface and branch into capillaries.
• Provide heart with oxygen-rich blood.

Electrical System

• Electrical impulses start in the right atrium.
• Travel through pathways to the ventricles, signaling them to pump.
• Conduction system ensures coordinated and normal heart rhythm.

Importance of Blood Exchange

• Continuous exchange of oxygen-rich and oxygen-poor blood is vital for life.