Bio Transport in Man

Transport in Man (chapter 6) Purpose: to transport substances from one organ to another in an efficient manner. Paramechia unicellular contractile Vacuoles: Collecting substances to transport to other parts of the cell. If it is a waste substance, it will be removed from the cell. Diffusion helps to move substances in and out of the cell through the cel membrane, which works out because the cell is in constant contact with everything. However, this does not work for multicellular organisms. too many layers of cells that are not in contact with surroundings, hence nutrients and water cannot diffuse into the body like unicellular organisms. It would also be difficult to remove waste products in time just by simple diffusion, Hence, a transport system is present to carry substances from one part of the body to another. Blood: Red Blood Cell: Function: To transport oxygen from the lungs to other parts of the body. Adaptations: a. circular biconcave shape i. increased surface area to volume ratio to increase the efficiency of absorption b. no nucleus i. so that it can carry more haemoglobin c. contain red pigment called haemoglobin i. haemoglobin is a substance that can reversibly combine with oxygen d. are flexible The RBC’s haemoglobin binds with oxygen in the lungs (where oxygen concentration is high) to form oxyhaemoglobin. In tissues where oxygen concentration is low, oxyhaemoglobin releases the contained oxygen to the tissue cells. Transporting is not the same as needing. Eg: RBC does not use oxygen when transporting it. Plasma: A yellowish liquid found in blood. It contains mostly water (a good solvent, which allows for most of the substances to be dissolved). and substances like glucose, salts, proteins, amino acids, fats, vitamins, hormones and excretory products like urea. It also contains red and white blood cells.

Function: to transport: a. blood cells around the body b. nutrients from the small intestines to other parts of the body c. excretory products from organs where they are produced to excretory organs for removal d. hormones from endocrine glands to target organs. It also contains antibodies. White Blood Cell: Two types: a. Phagocytes i. Function: perform phagocytosis 1. Phagocytosis is a process in which a WBC engulfs and destroys foreign particles like bacteria ii. Adaptation: 1. Can move on its own b. Lymphocytes i. Function: produce antibodies (protein based) that 1. recognise foreign particles 2. engulf and destroy disease-causing organisms (pathogens) like bacteria and viruses 3. cause bacteria to clump together for each engulfing /ingestion by phagocytes 4. neutralise toxins produced by bacteria They are irregular in shape and each have a nucleus Platelets: Function: to be involved in blood clotting Platelets are fragments of cytoplasm that contain: a. Thrombin (an enzyme) that catalyses the conversion of fibrinogen to form sticky fibrin threads (they are only sticky with exposure to outside air) which: i. form a network that entangles RBCs to form a clot which: 1. prevents excessive blood loss 2. prevents the entry of harmful organisms (pathogens) into the bloodstream Blood Clotting: Blood exposed to air will quickly coagulate (it is also like denaturing but please don’t say denaturing, becomes sticky and solidifies to form clots)/clot. This clot seals the wound and

performs aforementioned functions. Fibrinogen breaks down with the help of Thrombin (an enzyme) into the long fibrin thread. Collagen is exposed when the skin is broken, which attracts platelets to seal the wound. A scab is essentially the platelets and blood cells that are used as the blood clot. It covers the wound as the skin heals and falls off once the skin is completely healed. For people with the hereditary disease called haemophilia, their ability to blood clot is severely impaired. Slight injuries, if not immediately treated, may cause them to bleed out or die from internal bleeding. Mechanism: a. Platelets are involved in converting fibrinogen to fibrin, this process involves thrombin, an enzyme. b. Fibrin threads entangle blood cells and the whole mass forms a clot or a scab. This seals the wound. Other information: The ratio of red blood cells to white blood cells it about 1:100 Tissue Rejection: In an organ transplant, an organ/tissue when failing would be replaced with another person’s organ. However, when the white blood cells recognise it as a foreign body (any organ from another person may be treated as a foreign body), these white blood cells would work to produce antibodies to destroy the foreign organ/tissue. This is tissue rejection. Methods to reduce chances of tissue rejection: a. find a genetically similar person b. use immunosuppressant drugs to inhibit the responses of recipient’s immune system Blood Transfusion:

Other blood types (not in syllabus): Rh-null blood (Golden Blood) - it has no antigens at all and is extremely rare, with only >50 cases identified worldwide. It is literally the universal donor, but they can only take from another Rh-null donor. When a person loses too much blood, a doctor will transfer blood from one person to this person. Genetics defines blood types (A, B, AB, O (the only recessive one) The positive or negative is from the genetics too (rhesus factor aka Rh factor) This stems from the antigen called Rh. If present, the blood type is positive and vice versa. There are more than 50 different Rh antigens too. When two different blood types mix (specifically contrasting ones): the blood will agglutinate (v: agglutinating) and cause clumps in the blood that block blood vessels, which cause death. Outside the blood cell membrane, there are antigens (either A and/or B depends on blood type) on it. This allows for the immune system to identify cells and determine whether they are foreign or not. O does not have any antigens on the outside of the blood cell membrane. Antigens and Antibodies:

ANtibodies bind to specific antigens Blood Type A has antigen A and the plasma has antibody b. Blood Type B has antigen B and plasma has antibody a. Blood Type O has no antigens and the plasma has antibodies a and b. Blood type AB has both antigens A and B and the plasma has no antibodies.

The antibodies in this blood DO NOT FIGHT BACTERIA. Typically, antibodies are represented by lowercase letters. When blood is donated, it is usually separated into components (red blood cell, plasma, platelets) for transfusion. Most of the time, only the red blood cells are donated. This basically means that only the antigens are w