circulatory system

• What is the role of arteries in the circulatory system?

  Distribute blood under high pressure
• What is the structure of arteries in relation to their function?

  Thickest and strongest walls for high pressure
• What is the pressure of blood in the aorta?

  About 120 mmHg
• How do main arteries function in the body?

  Distribute blood to regions under high pressure
• What happens to blood pressure as arteries become wider?

  Pressure lowers as flow increases
• What is the function of arterioles?

  Deliver blood to the tissues
• What is the pressure of blood in capillaries?

  About 35 mmHg
• How do capillaries serve the tissues and cells of the body?

  Facilitate exchange between blood and tissue
• What allows capillary walls to accommodate blood surges?

  Walls stretch due to elastic and collagen fibres
• What happens to elastic fibres in arteries during blood flow?

  They stretch and then recoil
• How does the tunica media change with distance from the heart?

  Contains more smooth muscle and fewer elastic fibres
• What is the role of smooth muscle fibres in arteries?

  Regulate blood flow through constriction and dilation
• What is the diameter of capillaries?

  About 7 µm
• Why do capillaries reduce flow rate?

  To increase exchange between blood and tissue
• What are the walls of capillaries made of?

  A single layer of endothelial cells
• What do the gaps between capillary cells allow?

  Components of blood to escape into tissue fluid
• What is the structure of veins compared to arteries?

  Have thin walls; tunica externa is thickest
• What is the pressure of blood in veins?

  About 5 mmHg
• How do veins accommodate low pressure blood flow?

  Widen to lower pressure and increase flow rate
• What is the composition of vein walls?

  Endothelium and thin tunica media
• What prevents backflow of blood in veins?

  Presence of valves
• What units are used to measure pressure in medicine?

  Millimetres of mercury (mmHg)
• How is pressure measured in scientific contexts?

  Using pascal (Pa) and kilopascal (kPa)
• What is the conversion between mmHg and kPa?

  1 mmHg = 0.13 kPa
• Functions of circulatory system?

  Transport of g ases, s oluable n utrients, f atty a cids, w ater (for hydration), i mmune c ells and c omponents, w aste, and h eat
• What are the main components of blood?

  Plasma and cellular elements
• What is the function of plasma in blood?

  Solvent for carrying other substances
• What percentage of blood is plasma?

  55%
• What percentage of blood is made up of cellular elements?

  45%
• How many erythrocytes are typically found per mm³ of blood?

  5-6 million
• What is the primary function of erythrocytes?

  Transport of oxygen and carbon dioxide
• What is the range of leukocytes per mm³ of blood?

  5,000-10,000
• What is the main role of leukocytes?

  Defense and immunity
• What are the major functions of blood components?

  • Water: Solvent for carrying substances
  • Erythrocytes: Transport oxygen and carbon dioxide
  • Salts: Osmotic balance and pH buffering
  • Leukocytes: Defense and immunity
  • Plasma proteins: Osmotic balance, clotting, immunity
  • Platelets: Blood clotting
• What are the types of leukocytes mentioned?

  Basophil, eosinophil, lymphocyte, neutrophil, monocyte
• What is the function of plasma proteins?

  Osmotic balance, pH buffering, clotting, immunity
• How many platelets are typically found per mm³ of blood?

  250,000-400,000
• What is the role of platelets in blood?

  Blood clotting
• What substances are transported by blood?

  • Nutrients (e.g., glucose, fatty acids, vitamins)
  • Waste products of metabolism
  • Respiratory gases (O2 and CO2)
• What is the role of erythrocytes in gas transport?

  Transport oxygen to cells and carbon dioxide to lungs