4. Blood vessels

• What are the main types of blood vessels and their functions?

  • Arteries: Carry oxygenated blood to tissues
  • Veins: Carry deoxygenated blood to lungs
  • Capillaries: Facilitate exchange between blood and tissues
• What is the function of arteries in the circulatory system?

  Carry oxygenated blood to body tissues
• Why do arteries have a small lumen?

  To maintain high blood pressure
• What is the role of smooth muscle in arteries?

  To control diameter through contraction and relaxation
• What do veins carry to the lungs?

  Deoxygenated blood
• Why do veins have valves?

  To prevent backflow of blood
• What is the structure of capillaries?

  Very small with a narrow lumen
• What is the purpose of the thin endothelium in capillaries?

  To maintain short diffusion distance
• Blood vessel types


  The different types of blood vessels, including arteries, veins, and capillaries
• Structure and function of an artery

  1. Thick muscular walls to withstand high blood pressure
  2. smaller lumen than vein because of the thick muscle walls
  3. elastic fibres to contract and dilate to maintain high blood pressure
  4. smooth endothelium lining to prevent resistance of blood flow
• Structure and function of vein

  1. Thinner walls than an artery’s
  2. Bigger lumen for more volume of blood flow
  3. Valves to prevent backflow
  4. Low pressure of blood
• structure and function of capillaries

  1. one cell thick walls for rapid gas exchange
  2. large network of capillaries for efficient diffusion
  3. large supply of blood, for gas exchange
• Structure of arteries

  • Thick muscular walls: to withstand high pressure from blood pumped by the heart.
  • Elastic tissue: allows the artery to stretch and recall maintaining blood pressure.
  • Smooth muscle: control the diameter of the artery regulating blood flow.
  • Endothelium inner lining: smooth to reduce friction and allow efficient blood flow.
  • Narrow lumen: maintains high blood pressure
• Function of arteries

  • Oxygenated blood away from the heart
  • Maintain high pressure to ensure blood reaches all tissues efficiently
  • Pulse is felt due to the elastic recoil of archery rules after each heartbeat  
• What is the structure of veins compared to arteries?

  Thinner walls than arteries
• Why do veins have thinner walls than arteries?

  Blood pressure in veins is much lower
• What type of tissue is less present in veins compared to arteries?

  Elastic and muscle tissue
• Why do veins have a wider lumen?

  To reduce resistance to blood flow
• What is the function of valves in veins?

  Prevent backflow of blood
• How does the endothelium in veins function?

  It provides a smooth lining to reduce friction
• What type of blood do veins carry back to the heart?

  Deoxygenated blood
• What is the exception to veins carrying deoxygenated blood?

  The pulmonary vein carries oxygenated blood
• How do veins operate under low pressure?

  They rely on skeletal muscle contractions and valves
• What condition is caused by valve failure in veins?

  Varicose veins
• What is deep vein thrombosis (DVT)?

  Blood clots in deep veins, often in legs
• What is the structure of capillaries?

  One cell thick walls
• Why are capillary walls one cell thick?

  To enable efficient diffusion
• What is the lumen size of capillaries?

  Very narrow lumen
• What is the significance of capillaries having no valves or muscle?

  It allows for passive blood flow
• What feature of capillaries increases their surface area?

  Extensive branching
• What is the primary function of capillaries?

  Exchange of gases, nutrients, and waste
• What do capillaries connect?

  Arterioles to venules
• What processes occur in capillaries?

  Diffusion, osmosis, and filtration
• What can capillary damage lead to?

  Tissue swelling (edema)
• What are the key structural differences between arteries, veins, and capillaries?

  • Arteries: Thick walls, elastic tissue, narrow lumen
  • Veins: Thinner walls, less elastic, wider lumen, valves
  • Capillaries: One cell thick, very narrow lumen, no valves
• What are the functions of arteries, veins, and capillaries?

  • Arteries: Carry oxygenated blood away from heart
  • Veins: Carry deoxygenated blood back to heart
  • Capillaries: Exchange gases, nutrients, and waste
• What are the clinical relevance issues related to veins and capillaries?

  • Varicose veins: Caused by valve failure
  • Deep vein thrombosis (DVT): Blood clots in deep veins
  • Capillary damage: Leads to edema
  • Diabetic microangiopathy: Damage to capillaries
• Why do arteries have a folded endothelium

  To stretch and to accommodate high pressure