Circulatory System: Blood Vessels

Overview

• Focus on blood vessels: arteries, capillaries, and veins.
• Arteries: Carry blood away from the heart.
• Capillaries: Exchange nutrients and oxygen with tissues.
• Veins: Carry blood back to the heart.

Arteries

• Function: Transport blood at high pressures from the heart.
• Structure:
  • Thick muscle layer: Provides strength.
  • Thick elastic tissue: Allows stretching and recoiling.
  • Thick walls: Compared to lumen (the central hole).

Capillaries

• Function: Exchange substances (e.g., nutrients, oxygen) with cells; remove waste (e.g., carbon dioxide).
• Structure:
  • Single cell thick walls: Facilitates diffusion.
  • Permeable walls: Easier substance exchange.
  • Tiny lumen: Large total cross-sectional area, lowers blood pressure.
  • Slow blood flow: Provides time for exchange with tissues.

Veins

• Function: Return blood to the heart.
• Structure:
  • Large lumens: Largest of all blood vessels.
  • Thin walls: Small layers of elastic fibres and smooth muscle.
  • Valves: Prevent backflow, ensure blood flows towards the heart.

Calculation of Blood Flow Rate

• Example Problem:
  • Calculate the rate of blood flow.
  • Given: 2560 ml of blood through the aorta in 8 minutes.
  • Solution: Divide 2560 ml by 8 minutes = 320 ml/minute.

Additional Resources

• Links to videos on the heart and blood provided in the description.