Blood Vessels

O Whāinga Ako

1. Describe the function and structure of arteries, veins, capillaries

Blood Vessels

• Any tube that carries blood within the body is called a blood vessel
• There are three that we are interested in:
  • Arteries
  • Veins
  • Capillaries

Arteries

• Carry blood away from the heart
• Have a thick outer layer of elastin
  • This is important because the artery expands as the pulse travels through it
• Have a thick layer of muscle
  • Strong to resist the high blood pressure
• Relatively narrow lumen for the blood to travel through
  • This keeps the blood at a high pressure and moving quickly

Veins

• Carry blood towards the heart
• Have a thin layer of muscle
  • This is because veins are not at such a high pressure
• Have a large lumen so that more blood can flow with less friction
• Have one-way valves to stop backflow of deoxygenated blood.

Capillaries

• Carry blood to individual cells
• This is where oxygen is transferred from the blood to the cells
• Extremely narrow
  • This is important because it helps get blood to every cell
• Vessel wall about one cell thick
  • The narrow vessel wall also helps oxygen and nutrients move from the capillary into the cell

Ngohe/Task: Compare and Contrast

1. Head up a section in your book Arteries vs Veins
2. Make three columns across your page
   • Arteries
   • Both
   • Veins
3. Summarise your notes into the three columns. The differences, and things that they have in similar!
4. Sketch a diagram of each at the bottom of the column