Blood vessels

• Name 4 blood vessels that are attached to the heart.

  • vena cava, aorta, pulmonary artery and pulmonary vein
• What do the coronary arteries do?

  Supply blood to the heart muscle
• Name two blood vessels that are attached to the lungs.

  pulmonary artery and pulmonary vein
• Name two blood vessels that is attached to the kidneys.

  renal artery and renal vein
• What does the term pulmonary refer to?

  Lungs
• What does the term renal refer to?

  Kidneys
• Describe the structure of arteries.

  • Thick muscular layer
  • thick elastic layer
  • thick outer layer
  • small lumen
  • no valves
• Describe the capillary endothelium.

  • Extremely thin
  • one cell thick
  • contains small gaps for small molecules to pass through (e.g. glucose, oxygen)
• Complete the following about capillaries:

  • Form capillary beds
  • narrow diameter (1 cell thick) to slow blood flow
  • red blood cells squashed against walls shortens diffusion pathway
  • small gaps for liquid / small molecules to be forced out
• Describe the structure of arterioles.

  • Branch off arteries
  • thickest muscle layer to restrict blood flow
  • thinner elastic layer and outer layer than arteries as pressure lower
• Complete the following about coronary arteries.

  • Blood vessels supplying cardiac muscle with oxygenated blood
  • branch off from aorta
  • if blocked, cardiac muscle will not be able to respire, leading to myocardial infarction (heart attack)
• How is the aorta adapted to carry blood at very high pressure?

  • Contains elastic tissue, which stretches when the ventricles contract and recoils when they relax
  • This helps to smooth out blood flow and maintain consistent pressure
  • Has a thick muscular wall which helps it withstand high pressure & prevents bursting.
  • The smooth endothelium also reduces friction.
• How are arteries adapted to maintain high pressure?

  They have thick muscular and elastic walls and a narrow lumen.
• What is the function of arterioles?

  Arterioles branch from arteries and help to regulate blood flow into capillaries.
• What adaptations do arterioles have?

  Thicker layer of muscle which can contract to narrow the lumen which reduces blood flow to the capillaries
• What do veins do?

  Veins carry blood back to the heart under low pressure.
• What adaptations do veins have?

  • Thinner walls with less muscle and elastic tissue
  • Wider lumen to reduce resistance flow
  • Valves to prevent the backflow of blood
• How are capillaries adapted for the exchange of substances between the blood and the surrounding tissues?

  • Walls one cell thick which reduces diffusion distance, allowing for faster exchange of substances
  • Narrow diameter which causes red blood cells to pass through in single file, increasing their contact time with the capillary wall, improving the efficiency of gas exchange.
  • Capillary beds (large networks of capillaries) provide a large surface area for faster gas exchange.