circulatory system

• what are the three main components of the circulatory system

  blood, blood vessels, the heart
• what are the two main functions of the circulatory system

  - Transportation of substances

  - Protection against disease
• what are the 4 main components of the blood

  plasma, red blood cells, white blood cells, platelets

  
• describe the function of RBCs

  carry oxygen
• describe the structure of RBCs

  Contain haemoglobin (rich in iron) to carry oxygen. Biconcave shape to provide a large surface area for the diffusion of oxygen. No nucleus to provide more space for haemoglobin.
• describe the function of WBCs

  Defend the body against disease.
• describe the structure of WBCs

  Large cells that contain a nucleus. There are 2 types: Lymphocytes - make antibodies. Phagocytes - engulf and digest microorganisms.

  
• function of platelets


  Convert fibrinogen to fibrin. Fibrin forms a mesh that traps blood. Important in blood clotting and scab formation.
• structure of platelets


  Cell fragments (very small).
• function of plasma


  Transports blood cells, digested food molecules (e.g. glucose), carbon dioxide, urea and hormones.
• structure of plasma


  Yellow coloured liquid.
• what will happen if RBCs are placed in a high concentration of water? what is this called


  osmosis will cause water to move into the cell and, without a cell wall, they will lyse (burst). this is called cell lysis
• how is cell lysis prevented

  Salts and other chemicals are present in the blood plasma to keep its concentration similar to the concentration of the blood cells.
• give 4 difference between WBCs and RBCs

  1. RBC smaller than WBC

  2. more RBC than WBC

  3. RBC have no nucleus

  4. there are different types of WBC
• what is the direction of blood flow in an artery


  away from the heart
• what is the lumen diameter in an artery


  small
• what is the wall thickness in an artery


  thick
• what is the blood pressure in arteries


  high

  -walls need to stretch
• direction of blood flow in a vein


  towards the heart
• lumen diameter in veins


  large
• wall thickness in veins


  thin
• blood pressure in veins


  low
• direction of blood flow in capillaries


  from arteries to veins
• lumen diameter in capilaries


  small
• wall thickness in capillaries


  one cell thick
• blood pressure in capiliaries


  low
• which blood vessel has valves and why


  Veins; there is low blood pressure in the veins system so the valves prevent backflow
• What do arteries usually carry?

  Oxygenated blood from the heart to the rest of the body.
• What is the exception to arteries carrying oxygenated blood?


  The pulmonary artery, which carries deoxygenated blood from the heart to the lungs.
• What is a key structural feature of arteries?

  They have thick walls with muscle and elastic fibers to withstand high pressure.
• What allows arteries to expand and recoil with each surge of blood?

  Muscle and elastic fibers within the walls of the arteries.
• What do veins usually carry?

  Deoxygenated blood from the body back to the heart.
• What is the lumen of veins like?


  The lumen is large and reduces friction as the blood moves through.
• What is the exception to veins carrying deoxygenated blood?


  The pulmonary vein, which carries oxygenated blood from the lungs to the heart.
• Why do veins have very few muscle and elastic fibers?


  Because blood does not surge through veins.
• What is the function of capillaries?


  Allow the diffusion of substances (e.g. oxygen, carbon dioxide, dissolved food and urea) between the blood and the body's cells or vice versa.
• What type of surface do capillaries provide for diffusion?

  A thin, permeable surface
• What does the right side of the heart do?


  pumps deoxygenated blood (low in oxygen and high in carbon dioxide) to the lungs.
• What does the left side of the heart do?


  pumps oxygenated blood (high in oxygen and low in carbon dioxide) to the organs of the body.
• describe what happens in the heart

  1. Deoxygenated blood enters the right atrium from the vena cava.

  2. Blood moves into right ventricle.

  3. Blood is pumped into the pulmonary artery.

  4. The pulmonary artery carries deoxygenated blood to the lungs.

  5. The blood becomes oxygenated in the lungs.

  6. Oxygenated blood leaves the lung via the pulmonary vein.

  7. Blood enters the left atrium.

  8. Blood moves into the left ventricle.

  9. Blood is pumped into the aorta, which carries oxygenated blood around the body.