blood vessels + changes in blood pressure

• What is the diameter and wall thickness of veins compared to arteries?

  Veins have larger diameters and thinner walls
• Why do veins have semi-lunar valves?

  To prevent backflow of blood
• How do skeletal muscles assist in blood flow towards the heart?

  They massage blood upward towards the heart
• What happens to blood when skeletal muscles relax?

  Blood falls downward due to gravity
• How do valve pockets function in veins?

  They fill with blood and close to prevent backflow
• What is the primary function of capillaries?

  To allow rapid exchange of substances
• Where do capillaries form a network?

  Throughout every tissue except cornea and cartilage
• What is the structure of capillary walls?

  Thin walled with only a layer of endothelium
• What are fenestrations in capillaries?

  Tiny gaps allowing blood components to leak out
• What substances can capillaries be permeable to?

  Water and dissolved substances like glucose
• Where is the highest blood pressure found?

  In the aorta and arteries
• What causes the rhythmical rise and fall of pressure in arteries?

  Contraction and relaxation of the heart's ventricles
• Why do arterioles experience a pressure drop?

  Friction with vessel walls causes pressure drop
• How do arterioles control blood flow?

  By adjusting their diameter to dilate or contract
• What happens to blood pressure in capillaries?

  Pressure drops due to leakage into tissues
• Why is blood flow slowed in capillaries?

  To allow time for the exchange of substances
• What is the pressure condition in veins?

  Pressure in veins is low
• How can pressure in veins be increased?

  By the massaging effect of muscles
• What are the key features of blood vessels?

  • Veins: larger diameters, thinner walls, valves
  • Capillaries: thin-walled, allow substance exchange
  • Arteries: highest pressure, rhythmical pressure changes
  • Arterioles: adjust diameter, pressure drop due to friction