11.1.6 Blood Vessels, Blood & Lymphatic Vessels

• What does the hepatic portal vein connect?

  The small intestine and the liver
• Why is the blood in the hepatic portal vein deoxygenated?

  Because it has come from respiring intestinal cells
• What nutrients are high in the blood from the hepatic portal vein?

  Glucose, amino acids, glycerol, and fatty acids
• What are the main structural differences between arteries, veins, and capillaries?

  • **Arteries**: Thick muscular walls, small lumen, elastic tissue, fast blood flow.
  • **Veins**: Thinner walls, larger lumen, valves present, slow blood flow.
  • **Capillaries**: Microscopic, one cell thick, very low blood pressure, leaky walls.

  
• What is the primary function of arteries?

  To carry blood away from the heart
• What is unique about the pulmonary artery?

  It carries deoxygenated blood from the heart to the lungs
• What is the primary function of veins?

  To carry blood to the heart
• Why do veins have valves?

  To prevent blood from flowing backwards
• How does muscle contraction assist veins?

  It helps blood flow back to the heart
• Where are capillaries primarily found?

  In the muscles and lungs
• What is the significance of capillaries being one cell thick?

  It allows for a short diffusion distance
• What occurs at the capillaries during gas exchange?

  Oxygen diffuses into tissues and carbon dioxide diffuses into the blood
• What do capillaries allow to leave the blood plasma?

  Small substances like water, glucose, and salts
• What is the composition of blood?

  Plasma, red blood cells, white blood cells, and platelets
• What is plasma primarily made of?

  Water with dissolved substances
• What is the primary function of red blood cells?

  To transport oxygen for aerobic respiration
• What adaptations do red blood cells have for their function?

  Contain haemoglobin, no nucleus, small and flexible, biconcave shape
• What is oxyhaemoglobin?

  Oxygen combined with haemoglobin
• What is the role of phagocytes?

  To remove microorganisms that invade the body
• What process do phagocytes use to ingest pathogens?

  Phagocytosis
• How do phagocytes destroy pathogens?

  By engulfing them and using enzymes in the cytoplasm
• What is the primary function of lymphocytes?

  To recognize bacteria and viruses as 'foreign'
• What do lymphocytes produce?

  Proteins called antibodies
• How do antibodies function?

  They are specific to the antigen on the pathogen and help in its destruction
• What happens when platelets are damaged?

  They release blood-clotting enzymes
• What is fibrinogen converted into during blood clotting?

  Fibrin
• What does fibrin do in the blood clotting process?

  It forms a mesh of fibers to trap red blood cells
• What is the purpose of a scab?

  To prevent blood loss and stop pathogens from entering the body
• What are the key components of blood and their functions?

  • **Plasma**: Transports nutrients, hormones, and waste.
  • **Red Blood Cells**: Carry oxygen for respiration.
  • **White Blood Cells**: Protect against infection (phagocytes and lymphocytes).
  • **Platelets**: Involved in blood clotting.