Lecture Notes: The Circulatory System and the Heart

Introduction to the Circulatory System

• Also known as the cardiovascular system
• An organ system comprising:
  • Heart
  • Blood vessels
  • Blood
• Primary function: Transport substances around the body
  • Oxygen
  • Nutrients
  • Cells
  • Waste products

Double Circulatory System

• Consists of two separate circuits:
  1. Pulmonary Circuit
     • Blood flows from the heart to the lungs and back to the heart
  2. Systemic Circuit
     • Blood flows from the heart to body tissues (muscles, brain, liver, etc.) and back to the heart
• Process:
  • Blood is pumped from the heart to the lungs, back to the heart, then around the body, and returns to the heart

The Heart

• Functions as a muscular pump
• Contains four chambers:
  • Atria (Top chambers)
  • Ventricles (Bottom chambers)
• Chambers:
  • Right Atrium and Right Ventricle
    • Separated by the right atrioventricular valve
  • Left Atrium and Left Ventricle
    • Separated by the left atrioventricular valve
• Note on Orientation:
  • When viewing the heart, the left and right labels are based on the heart's perspective, not the viewer’s
• Left Ventricle has a thicker wall than the Right Ventricle due to the need to pump blood throughout the body

Blood Vessels of the Heart

• Vena Cava
  • Largest vein; carries deoxygenated blood from the body to the heart
• Pulmonary Artery
  • Carries deoxygenated blood from the right ventricle to the lungs
• Pulmonary Vein
  • Carries oxygenated blood from the lungs to the left atrium
• Aorta
  • Largest artery; carries oxygenated blood from the left ventricle to the body

Heart Muscle Blood Supply

• Coronary arteries branch off the aorta
• Supply the heart muscle with oxygenated blood
• Blockage can lead to coronary artery disease or heart attack

Additional Resources

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