blood vessels

• What is the primary function of the heart in the circulatory system?

  It acts as the system's pump
• What are the three types of blood vessels discussed?

  Arteries, capillaries, and veins
• What is the role of arteries in the circulatory system?

  • Carry blood away from the heart
  • Transport oxygenated blood (except pulmonary arteries)
• What is the function of capillaries?

  • Exchange nutrients and oxygen with tissues
  • Remove waste products like carbon dioxide
• What do veins do in the circulatory system?

  • Carry blood back to the heart
  • Transport deoxygenated blood (except pulmonary veins)
• Why do arteries need to be strong and elastic?

  To withstand high blood pressure from the heart
• What is the structure of arteries that helps them bear high pressure?

  Thick layers of muscle and elastic tissue
• What is the lumen in blood vessels?

  The hole or space in the middle
• How are capillaries adapted for their function?

  They have walls that are one cell thick
• Why do capillaries have a lower blood pressure than arteries?

  Because blood flows more slowly in capillaries
• What is the total cross-sectional area of capillaries compared to arteries?

  It is much larger than for arteries
• What do veins have to prevent blood from flowing backwards?

  Valves
• Why do veins have thinner walls than arteries?

  Because they carry blood at low pressures