body + heart

• what does the circulatory system include of?

  heart, blood vessels and blood
• what‘s the benefit of a circulatory system?

  1. efficient transport
  2. lowers the pressure by reducing the speed it can flow
• what do arteries do?

  carry oxygenated blood away from the heart to the rest of the body.
• what can arteries do?

  1. withstand high pressure from the heart
  2. maintain the pressure when the heart is relaxed
• what’s arteries’ structure?

  1. thick walls
  2. elastic fibers
• what are arteries’ walls layered with?

  smooth muscle
• why do elastic fibers benefit arteries?

  allow the walls to expand when around blood
• what do veins do?

  veins carry deoxygenated blood back to the heart.
• what’s veins’ structure?

  1. thin walls
  2. prevent a back flow of blood
• what do capillaries do?

  1. connect arteries and veins
  2. transport blood, nutrients and oxygen to cells/organs
• what’s capillaries’ structure?

  1. thin walls (1 cell thick)
• how do capillaries’ thin walls benefit the human body?

  1. reduces the diffusion distance for oxygen and carbon dioxide
  2. walls have pores allowing blood plasma to leak out and form tissue liquid