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  1. 1. BLOOD What percent of the human body is blood? How much blood do we contain? On average 4-6 liters 8%
  2. 2. COMPOSITION OF BLOOD  Blood consists of a : Liquid component: PLASMA Solid component: BLOOD CELLS
  3. 3. How much is there of each component?
  4. 4. Plasma can be separated from the blood cells. How? Centrifugation plasma
  5. 5. Plasma is a clear, yellow fluid Percentage of water in plasma : Substances dissolved in plasma:  Glucose  Amino acids  Vitamins  Minerals  Lactic acid Layering of blood components in a centrifuged blood sample. 90%  Hormones  Urea  Respiratory gases  Antibodies  Proteins
  6. 6. Question: MAY, 2010 Name the liquid component of blood and list TWO substances dissolved in it. (3) Amino acids Glucose [any two from previous list. FOOD is wrong] PLASMA
  7. 7. Function of plasma: to provide a medium through which continual exchange between cells and blood takes place Blood flow Body cells
  8. 8. Three types of blood cells: a) ERYTHROCYTES or red blood cells b) LEUCOCYTES or white blood cells c) PLATELETS or thrombocytes Leucocytes & platelets Erythrocytes Plasma
  9. 9. Red blood cells (RBC) are formed in the red bone marrow of the: Ribs Sternum Vertebrae
  10. 10. RBC are:  very small and numerous  disc-shaped (BICONCAVE) without a nucleus  contain the red pigment HAEMOGLOBIN  function of RBC: to transport oxygen & some carbon dioxide
  11. 11. About 2 million RBC per second are made but production is faster at high altitude. Why? There is not so much oxygen in the air.
  12. 12. Average life span of a RBC: 120 days  the old and worn out RBC are broken down in the: liver spleen
  13. 13. What forms from the haemoglobin broken down?  IRON part: stored in liver  The rest of the haemoglobin molecule forms BILE PIGMENTS  bile pigments are excreted in bile Gall bladder stores bile
  14. 14. Red blood cells are adapted to carry oxygen: 1. biconcave disc shape offers maximum surface area for oxygen uptake 2. haemoglobin has a high AFFINITY for oxygen and combines with it, forming OXYHAEMOGLOBIN 3. no nucleus = more space for haemoglobin 4. being small makes it possible for oxygen to enter and leave the RBC quickly
  15. 15. Deoxygenated blood: Deep red-purple Oxygenated blood: Bright red
  16. 16. Fig. 3 Role of haemoglobin.
  17. 17. Carbon monoxide combines more readily with haemoglobin than oxygen does RBC do not carry oxygen to the cells Result:
  18. 18. WHITE BLOOD CELLS (WBC)  are less numerous than RBC  some live for months  most just a few days
  19. 19. Two types of WBC:  function of WBC: to protect the body against microbes LYMPHOCYTE PHAGOCYTE Lobed nucleus Spherical nucleus
  20. 20. Question: SEP, 2011 Draw a labelled diagram of: i) a red blood cell as seen in section; (2) ii) a white blood cell that engulfs and digests harmful bacteria. (3) Lobed nucleus i) ii)Cell membrane Cytoplasm Cell membrane Cytoplasm
  21. 21. Phagocytes are adapted to engulf bacteria by having:  an irregular shape  a lobed nucleus Phagocytes can squeeze out of capillaries.
  22. 22. What is ‘inflammation’?  phagocytes move to an infected area to attack the microbes  when this happens the area becomes:  red  swollen  hot INFLAMMATION  pus may form Pus = accumulation of WBC + microbes
  23. 23. Lymphocytes are produced in the bone marrow :  and then move into the lymph nodes
  24. 24. Lymphocytes produce antibodies in response to antigens  antibodies are :  proteins  specific antigen: material foreign to the body e.g. a bacterium or virus
  25. 25. Antibodies begin the process of destruction of the microbe and phagocytes finish the job
  26. 26. Immunity is  a natural resistance to infection due to antibodies
  27. 27. Question: SEP, 2002 White blood cells fight microbes. The number of white blood cells increases to eliminate the pathogens. Phagocytes engulf and digest harmful bacteria while lymphocytes produce antibodies. Briefly explain why the presence of a large number of white blood cells in a blood sample, is an indication of the presence of an infectious disease. (3)
  28. 28. Platelets  are cell fragments without a nucleus  function : important in blood clotting
  29. 29. How does clotting take place? A clot begins to form when platelets are damaged. Platelets release a substance (thromboplastin / thrombokinase). Skin is cut. A series of chemical reactions occur that ends up by producing a meshwork of FIBRIN. 1 2 3
  30. 30. Clot dries up to form a scab
  31. 31. Blood clottin g
  32. 32. HAEMOPHILIA is an inherited disease where a person’s blood takes a very long time to clot Blood clot formation needs a clotting factor: missing in haemophiliacs.
  34. 34. SUMMARY OF THE BLOOD FUNCTIONS  TRANSPORT 1. Oxygen from the lungs to the tissues. 2. Carbon dioxide from the tissues to the lungs. 3. Urea from the liver to the kidney. 4. Digested food from the small intestine to the tissues. 5. Hormones from endocrine glands to target organs. 6. Heat from tissues, especially the muscles to the whole body.
  35. 35.  PROTECTION AGAINST MICROBES 1. By clotting it prevents fluid being lost from cuts and wounds. 2. It protects against disease by killing microbes. Phagocytosis
  36. 36.  HOMEOSTASIS - keeping a constant internal environment by: 1. keeping a constant body temperature - by spreading warmth evenly around the body 2. regulating the amounts of various substances in the tissues
  37. 37. TYPES OF BLOOD VESSELS Artery Vein Capillary Blood from the heart. Blood to the heart.
  38. 38. Circulatory System Veins Carry blood towards the heart. Venules Capillaries join to form venules. Blood Capillaries Walls are one cell thick. Partially permeable lining allows substances to diffuse quickly. Slow movement of blood. Heart Relaxed state: heart is filled with blood. Contracting heart: blood is being pumped with great force out to lungs and to rest of body. Arteries Artery carries blood away. Arterioles Branching of arteries.
  39. 39. What happens to an artery when it enters an organ? Branches into arterioles and finally into capillaries.
  40. 40. Comparison of blood vessels in structure Arteries Veins Capillaries 1) Walls have a thick muscle and elastic layer Walls have a thin muscle and elastic layer Walls are one cell thick
  41. 41. Capillaries are so thin that RBC have to squeeze through
  42. 42. Arteries Veins Capillaries 2) No valves present Valves present to prevent backflow No valves One-way flow
  43. 43. Explain the presence of valves in leg and arm veins. (2) Question: MAY, 2010
  44. 44. Explain the presence of valves in leg and arm veins. (2) Question: MAY, 2010 The contraction of muscles compressing veins helps push blood up through the leg and arm veins back to the heart. The valves allow the blood to flow towards the heart only.
  45. 45. Arteries Veins Capillaries 3) Fluid and WBC cannot pass through wall Fluid and WBC cannot pass through wall Fluid without proteins can pass through wall. WBC pass out between cells artery vein capillary
  46. 46. Veins act as blood reservoirs
  47. 47. Question: MAY, 2010 Explain the wide lumen diameter and thin walls in veins. (2) Veins can store a large volume of blood inside their wide lumen. Thin walls can easily extend to contain the blood.
  48. 48. Comparison of blood vessels in blood composition and flow Arteries Veins Capillaries 1) Flow is away from the heart Flow is towards the heart Flow is from artery to vein HEART
  49. 49. Arteries Veins Capillaries 2) Oxygenated blood except pulmonary artery Deoxygenated blood except pulmonary vein Mixed Pulmonary artery Vein Artery
  50. 50. Question: SEP, 2012 List ONE function of the arterial blood vessels (arteries). (2) To supply oxygen to the body cells.
  51. 51. Arteries Veins Capillaries 3) Rapid flow Slow flow Very slow flow 4) High pressure Low pressure Low pressure 5) Pulse strong No pulse No pulse
  52. 52. force exerted by circulating blood on the walls of blood vessels The pressure of the circulating blood decreases as blood moves away from the heart Blood Pressure refers to the:
  53. 53. TISSUE FLUID  bathes the cells and keeps them in the right condition  forms from the blood HOW?
  54. 54. Tissue fluid forms at a capillary bed under high blood pressure Arterial flow Venous flow Lymphatic flow As blood flows into capillaries: 1. Tissue fluid forms. 2. Some tissue fluid returns to the blood.
  55. 55. EXCHANGE AT A CAPILLARY BED  capillaries form a dense network in such a way that every cell is close to a capillary lymphatic vessel
  56. 56. tissue fluid lymphatic vessel Tissue fluid forms from plasma. Lymph forms from………….. 10% tissue fluid enters lymphatic system lymph tissue fluid plasma
  57. 57. Two properties of the capillary network to allow efficient exchange between the bloodstream & the cells: 1. Large surface area of the capillary network 2. Being one cell thick
  58. 58. What happens to the lymph that enters the lymphatic system? Lymph empties into subclavian veins.
  59. 59. The Lymphatic System
  60. 60. Question: SEP, 2010 Give a biological explanation for each of the following. Tissue fluid forms from blood. (4) Small molecules are forced out of the capillary at the arterial end under high blood pressure from the heart.
  61. 61. Comparison of blood plasma, tissue fluid and lymph Blood plasma Tissue fluid Lymph LOCATION Inside blood vessels Bathing living cells Inside lymph vessels Arterial flow Lymphatic flow Venous flow
  62. 62. Blood plasma Tissue fluid Lymph COMPOSITION Water, proteins, glucose, salts, hormones , amino acids Oxygen present Very little protein, otherwise similar Oxygen present More protein than tissue fluid but less than plasma. More lipids, otherwise similar. No oxygen CELLS RBC, WBC, platelets WBC WBC TRANSPORT Blood pressure forces fluid through capillary at the arterial end. Osmosis returns fluid at the venous end of the capillary From capillary under pressure and return by osmosis to capillary (90%) and 10% to lymph From tissue fluid by drainage under pressure
  63. 63. THE HEART  the heart muscle:  is called CARDIAC MUSCLE  works without getting tired  contracts automatically CORONARY ARTERIES supply the heart with oxygenated blood.
  64. 64. Blocking of a blood vessel by cholesterol Blocked coronary artery leads to a heart attack Dead muscle tissue due to lack of oxygen
  65. 65. Question: Suggest TWO ways in which a person’s lifestyle might lead to a blockage of the coronary arteries. 1. Lack of exercise. 2. Smoking. 3. Eating food rich in fats. 4. Excessive alcohol intake.
  66. 66. What happens to the blood pressure if a blood vessel is blocked? Normal blood flow Abnormal blood flow
  67. 67. The heart has four chambers atria  Two upper chambers: atria / auricles  Two lower chambers: ventricles ventricles A wall / septum separates the two sides. Why? To prevent mixing of deoxygenated blood on the right side from the oxygenated blood on the left. RIGHT LEFT
  68. 68. Four valves in the heart Tricuspid valve: Prevents backflow to right atrium Bicuspid valve: Prevents backflow to left atrium Semilunar valves: Prevent backflow to ventricles RIGHT LEFT Bicuspid valve Tricuspid valve Semilunar valves
  69. 69. Parts of the heart Atria: Receiving Chambers Ventricles: Pumping Chambers Valves: Control Flow Septum Divides the Heart
  70. 70. Vertical section: the heart Aorta Pulmonary vein Left atrium Right atrium Vena cava Tricuspid valve Pulmonary artery Right ventricle Tendon Left ventricle Semi-lunar valves Bicuspid valve
  71. 71. Superior vena cava brings blood from: head & arms
  72. 72. The atria have thinner walls than the ventricles Thin-walled atrium No need to build a high pressure as atria pump blood to the ventricles just below them. Ventricles pump blood further away so must have thicker walls to pump blood at high pressure. Thick-walled ventricle
  73. 73. Right ventricle has thinner walls than left ventricle Right ventricle pumps blood to lungs which are near to heart but left ventricle pumps to whole body. Thus less pressure is needed. Right ventricle Left ventricle
  74. 74. Question: SEP, 2010 Give a biological explanation for each of the following. Blood pressure is highest in the arteries and lowest in the veins. (4) Highest blood pressure in arteries: blood is pumped into them by heart. Lowest in veins: blood is far away from heart.
  75. 75. What is a ‘stroke’?  Interruption of oxygen supply to the brain  Caused by: A clot in an artery in the brain Breakage of an artery in the brain  Causes brain cells to be deprived of oxygen and die
  76. 76. It takes about 1 min. for blood to make 1 complete cycle
  77. 77. Ventricles contract Atria relax Ventricles relax Atria contract When ventricles contract blood moves: out of the heart When atria contract blood moves: into the ventricles
  78. 78. Are the ventricles in systole or in diastole? Systole: contraction Diastole: relaxation
  79. 79. Atria contract / Ventricles relax
  80. 80. Ventricles contract / atria relax
  81. 81. The events of the cardiac cycle
  82. 82. Question: SEP, 2011 During exercise the heart pumps out a greater volume of blood per minute than when the body is at rest. List TWO ways in which the heart can increase the volume of blood pumped out. (4) 1. Increase in heart beat rate. 2. Each beat becomes stronger.
  83. 83. Double circulation: blood passes twice through the heart for each circuit of the body Pulmonary circulation: Heart-lungs-heart Systemic circulation: Heart-body-heart
  84. 84. Double circulation is found in:  birds  mammals
  85. 85. Pulmonary vein Aorta Hepatic artery Renal arteryRenal vein Hepatic portal vein Vena cava Pulmonary artery Hepatic vein The blood transport system in humans
  86. 86. Question: SEP, 2007 A red blood cell is present in a vein. Describe how the red blood cell will reach the lungs. In your answer mention the blood vessels and the different chambers of the heart that the red blood cell must pass through. (4) The red blood cell present in a vein, enters the vena cava. The vena cava takes blood to the right atrium. Blood is pumped into the right ventricle and to the lungs via the pulmonary artery.
  87. 87. Question: SEP, 2007 Describe how a red blood cell in the lungs reaches a kidney. In your answer mention the blood vessels and the different chambers of the heart that the red blood cell must pass through. (5) The red blood cell leaves the lungs via the pulmonary vein and enters the left atrium. The blood is pumped into the left ventricle and out of the heart via the aorta. The red blood cell enters the kidney via the renal artery.
  88. 88. Question: MAY, 1998 Trace the path of a molecule of glucose from the capillaries of the small intestine to the brain. (5) A molecule of glucose is absorbed by the blood in the small intestine. It moves into the liver via the hepatic portal vein and out of it through the hepatic vein. Glucose enters the vena cava which takes blood to the right atrium. Blood is pumped into the right ventricle and to the lungs via the pulmonary artery. Blood leaves the lungs via the pulmonary vein and enters the left atrium. The blood is pumped into the left ventricle and out of the heart via the aorta. The aorta branches into many arteries and one such artery takes glucose to the brain.
  89. 89. Question: SEP, 2010 Give a biological explanation for each of the following. The hepatic portal vein links two organs. (4) The liver is connected to the gut by the hepatic portal vein. As soon as digested food is absorbed into the blood, it goes to the liver. The liver removes extra amino acids by deamination and stores excess glucose as glycogen. Thus the liver plays a role in homeostasis.
  90. 90.  Explain why a baby born with a hole in its heart tires very easily. Deoxygenated blood from the right atrium flows into the left atrium where it mixes with oxygenated blood. The aorta carries this mixture to the muscles. The muscles do not receive enough oxygen. Adult heart Foetal heart
  91. 91. T H E E N D