Circulatory System - Blood Vessels

• Arteries carry blood away the heart.
• Capillaries carry blood through the body tissues, allowing oxygen, nutrients, and waste products, to be exchanged between tissues and the blood.
• Veins carry blood towards the heart.
• Roles and structure of the Arteries:

  1. Artery walls are strong and elastic as the heart pumps blood at a high pressure
  2. Thick middle layer containing both both muscle and elastic muscle.
  3. The muscle helps them be strong, and elastic fibres helps them to stretch and spring back.
  4. arteries have a relatively narrow lumen, which keeps the blood pressure high.
• Structure and function of capillaries 

  1. Capillaries are the smallest of the three blood vessels.
  2. The role of capillaries is to exchange nutrients and waste products with the tissues.
  3. Capillary walls are permeable, meaning substances are able to move through them.
  4. Their walls are also only one cell thick which means a short distance for diffusion.
  5. Capillaries carry blood at a low pressure and have a lower rate of flow than arteries.
• Substances are nutrients that are exchanged between the blood in the capillaries and the body tissues?

  Glucose and amino acids
•  waste products that are exchanged between the blood in the capillaries, and the body tissues?

  Urea and carbon dioxide
• Roles and function of the veins

  1. The role of veins is to carry blood from the body (or lungs) back to the heart.
  2. Veins are a similar size to arteries, but they have relatively thin walls and a relatively wide lumen
  3. This is because they carry blood at a much lower pressure.
  4. Veins also contain valves to prevent the blood from flowing backwards.
• substances are exchanged between the blood in the capillaries, and the body tissues?

  Urea Carbon dioxide oxygen and glucose
• Artery


  What is this

  
• B


  Based on the size of the lumen relative to the whole vessel, which of these blood vessels must be an artery?

  
• If you consider all the blood vessels inside of a human body, which type of blood vessel accounts for the majority of the cross-sectional area?

  Capillaries
• Heart ➔ artery ➔ capillaries ➔ veins ➔ heart