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Transport in Humans (part 1): Blood

Learning Outcomes<br>Students should be able to:<br>- state the role of blood in transport and defence<br>u2022 red blood cells u2013 haemoglobin and oxygen transport<br>u2022 plasma u2013 transport of blood cells, ions, soluble food substances, hormones, carbon dioxide,<br>urea, vitamins, plasma proteins<br>u2022 white blood cells u2013 phagocytosis, antibody formation and tissue rejection<br>u2022 platelets u2013 fibrinogen to fibrin, causing clotting<br>- list the different ABO blood groups and all possible combinations for the donor and recipient in<br>blood transfusions

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Transport in Humans (part 1): Blood

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  1. Transport in Mammals Chapter 8

  2. Lesson objectives • Circulatory system • Blood • Blood vessels – artery, vein, capillaries • Heart - structure & function - mode of action - diseases & relation to our diet

  3. The mammalian circulatory system 3 main parts: Heart • works as pump Blood • dissolves and carries materials Blood vessels • tubes for blood to flow along

  4. 1) Blood

  5. Warning!!! Do NOT come into contact with the blood of another person The danger of disease transmission is much too great

  6. Composition of Blood

  7. Four main components in blood Blood cells

  8. Composition of blood Plasma RBC (erythrocytes) Blood Blood cells WBC (leucocytes) Platelets

  9. Normal Blood

  10. Types of blood cells (white blood cells) (red blood cell) Any difference between the two?

  11. RBC • circular biconcave shape • no nucleus • diameter less than 0.01mm • elastic (can squeeze through capillary) • ~5 million RBC/mm3of blood • produced by bone marrow

  12. Physiology of red blood cells Each haemoglobin molecule can bind up to 4 molecules of oxygen

  13. How RBCs transport O2

  14. RBC • contain haemoglobin (red pigment) • enables O2transport (from lungs to rest of body) • lifespan 3-4 months • destroyed in spleen & liver Iron released • stored in liver breakdown haemoglobin Bile pigments • excreted in gut in the bile

  15. WBC • colourless (no haemoglobin) • larger than RBC • ratio RBC:WBC = ~700:1 • irregular in shape • has nucleus • can move and change shape (able to squeeze) • lifespan few days

  16. White blood cells (WBC) lymphocytes • produced by lymph glands/nodes • has large rounded nucleus + small amt. of non-granular cytoplasm 2 main kinds • produce antibodies phagocytes • produced by bone marrow • able to 1engulf and 2ingest foreign particles (phagocytosis) 2 types: monocytes & polymorphs

  17. Platelets • fragments of cytoplasm from certain bone marrow cells • Function: clotting of blood

  18. Functions of blood 1.Transport function 2.Protective function

  19. Function of blood 1. Transport function • Digested food substances • Excretory products (from tissues to excretory organs) e.g. nitrogenous waste products → kidneys carbon dioxide (bicarbonate ions) → lungs • Hormones • Heat • O2(from lungs to rest of body) 2. Protective function • Guards against infection • Blood clotting platelets plasma RBC WBC

  20. Protective function 1. Phagocytosis – process of engulfing & ingesting foreign particles e.g. bacteria by WBC 2. Antibody production (anti-toxins + agglutination) 3. Clotting/ coagulation of blood phagocytes lymphocytes

  21. Functions of antibodies 1. Destroy the bacteria by attaching to them, causing the bacterial surface membrane to rupture 2. Causes agglutination i.e. the clumping together of bacteria so that they can be easily ingested by the phagocytes 3. Neutralizing the toxins produced by bacteria (act as anti-toxins) 4. Attaching to viruses, making them unable to bind to the host cell

  22. Clotting of blood

  23. WBC (neutrophil) YEAST CELL Phagocytosis

  24. Macrophage engulfing bacteria

  25. Organ transplant and tissue rejection • Organ transplants involve the replacement of a damaged/diseased organ/tissue with a healthy one • Chances of new organ/tissue being rejected by the immune system of the recipient • Tissue rejection would not be a problem if the tissue to be transplanted comes from the same person e.g. coronary artery being replaced by artery from another part of the person’s body

  26. Preventing tissue rejection 1. Obtaining a tissue match. Tissue of donor and recipient has to be genetically as close as possible. Using immunosuppressive drugs which inhibit the activity of the recipient’s immune system Drawback: (i) Recipient becomes susceptible to many kinds of infections (ii) Recipient has to continue treatment for the rest of his life X-ray radiation of the bone marrow and lymphoid tissue may inhibit the production of blood cells → slows down the rejection process 2. 3.

  27. Blood Groups

  28. Types of blood groups • Blood group A • Blood group B • Blood group AB (universal recipient) • Blood group O (universal donor) What is the difference between the different blood groups?

  29. What causes agglutination of red blood cells? • The surfaces of red blood cells contain special proteins called antigens • The blood plasma (a.k.a. serum) contains natural antibodies which are always in the blood (unlike the antibodies produced by lymphocytes) • Natural antibodies will not react with the antigens on our red blood cells, but they may react with the antigens from another person causing agglutination (clumping).

  30. What happens when blood groups are incompatible during a blood transfusion? • Agglutination occurs i.e. clumping together of RBCs (due the reaction of antibodies with antigens → special proteins found on the surface of the RBCs) • Blocks up small blood vessels • Prevents the flow of blood • May result in death

  31. Differences between the blood groups Blood group Antigen on RBC Antibody in serum antigen A antibody b A antibody a antigen B B antigen A and B no antigen (universal donor) no antibodies (universal recipient) AB antibody a and b O Note: Antigens represented by capital letters A and B Antibodies represented by small letters a and b

  32. Agglutinated blood

  33. ***Why is blood group O the universal donor? • When blood group O blood is transfused into a person of blood group A, the recipient’s antibodies will not agglutinate with the donor’s red blood cells since the latter has no antigens. • At the same time, the donor’s (group O) antibodies a and b will be so diluted by the recipient’s blood that they do not have any effect on the recipient’s red blood cells Note: When a transfusion is carried out, we consider only the effect the recipient’s plasma has on the donor’s red blood cells

  34. ***Why is blood group AB the universal acceptor? • When blood group A or blood group B blood is transfused into a person of blood group AB, the recipient’s antibodies will not agglutinate with the donor’s red blood cells since the former has no antibodies. • At the same time, the donor’s (group A and B) antibodies a and b will be so diluted by the recipient’s blood that they do not have any effect on the recipient’s red blood cells Note: When a transfusion is carried out, we consider only the effect the recipient’s plasma has on the donor’s red blood cells

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