Lecture Notes: Components of the Circulatory System

Introduction

• Overview of the human circulatory system.
• Components:
  • Heart: Pumping organ (covered in previous session).
  • Blood Vessels: Network of tubes.
  • Blood: The fluid that circulates in the body.

Blood Vessels

• Function: Circulate blood throughout the body.
• Types of Blood Vessels:
  • Arteries:
    • Carry oxygen-rich blood away from the heart.
    • Thickest walls to withstand high pressure.
    • Narrow lumen.
    • No valves.
    • Located deep inside the body.
  • Veins:
    • Carry carbon dioxide-rich blood back to the heart.
    • Thin walls.
    • Large or wide lumen.
    • Contain valves to prevent backflow of blood.
    • Situated superficially (visible as bluish vessels under the skin).
  • Capillaries:
    • Connect arteries and veins.
    • Thinnest walls (single cell wide).
    • Extremely narrow lumen.
    • Located at the terminals of arteries and veins.
• Fact: If laid out in a line, blood vessels stretch for nearly 62,000 miles.

Blood

• Description: Fluid connective tissue that circulates in the human body.
• Functions: Transport nutrients, gases, and wastes.
• Composition:
  • Plasma (55%):
    • Yellowish-white fluid.
    • Contains water, nutrients, ions, proteins, and waste.
  • Cellular Components (45%):
    • Red Blood Cells (RBCs):
      • Also known as erythrocytes.
      • Carry oxygen and carbon dioxide.
      • Contain hemoglobin which binds with gases.
    • White Blood Cells (WBCs):
      • Also known as leukocytes.
      • Part of the body's defense system.
      • Help fight infections and diseases.
    • Platelets:
      • Assist in blood clotting.

Conclusion

• Major components of the circulatory system covered.
• Hint at the next session covering another system related to circulatory and immune systems.
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