Module 3 - Blood (Chapter 14) PDF

Chapter 14 Blood  Functions of Blood – Blood animation – transports vital substances – maintains stability of interstitial fluid – distributes heat  Blood Cells – 45% of blood – form mostly in red bone marrow – red blood cells – white blood cells – platelets (cell fragments...

Chapter 14 Blood  Functions of Blood – Blood animation – transports vital substances – maintains stability of interstitial fluid – distributes heat  Blood Cells – 45% of blood – form mostly in red bone marrow – red blood cells – white blood cells – platelets (cell fragments)  Blood Volume about 8% of body weight – varies with body size changes in fluid concentration changes in electrolyte concentration amount of adipose tissue **Average adult = ~ 5 liters of blood  Blood Composition Blood is 45% cells – hematocrit or packed cell volume 99% are red blood cells remainder are white blood cells blood platelets (formed elements of the blood) Blood is 55% plasma – water, amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, wastes  What could cause an increase in the hematocrit? What could cause a decrease in the hematocrit?  Origin of Blood cells Blood cells originate in red bone marrow from Hematopoietic stem cells Two proteins important in blood cell formation: - Erythropoietin - Thrombopoietin  po ietin ry thro i e tin E po o o mb r Th Formed Elements in Blood  Red Blood Cells Erythrocytes, RBC small, biconcave one-third hemoglobin – oxyhemoglobin – deoxyhemoglobin can readily squeeze through capillaries – Biconcave shape Mature RBC lacks nuclei – No DNA, no protein synthesis, no cell division – Have nucleus during early stages then gets rid of it More space for hemoglobin RBC lacks mitochondria - glycolysis only  RBC Life span is only 120 days – Energy requirements – Wearing out Eventually become less active, more rigid – Easily damaged Removed by liver and spleen Hemoglobin Molecule  Hemoglobin with 4 O2 bound to it is called oxyhemoglobin  bright red Hemoglobin with less than 4 O2 bound is called deoxyhemoglobin  dark red/blue – cyanosis  Red Blood Cell Production Erythrocytes are produced in the red bone marrow Erythropoietin – hormone that maintains RBC homeostasis – Operates in a negative feedback mechanism Low oxygen concentrations (decreased oxygen carrying capacity) – erythropoietin is released Primarily  Erythropoiesis Low blood oxygen - decrease oxygen carrying capacity of blood Kidneys (& liver) is stimulated to release erythropoietin Erythropoietin travels to the red bone marrow and stimulates hematopoietic stem cells to differentiate into RBCs – increase in RBC production Increases oxygen-carrying capacity of the blood – Increased athletic endurance Blood doping…….. Release of erythropoietin is then shut off – Negative feedback mechanism  Dietary Factors RBC production is influenced by: – Vitamin B12 required for DNA synthesis intrinsic factor (released by parietal cells in the stomach) necessary for absorption of vitamin B12 – Folic acid required for DNA synthesis – Iron required for hemoglobin synthesis – Vitamin C increases absorption of iron  Anemia Deficiency in RBC or reduction in amt of hemoglobin they contain: Iron deficient anemia – lack of dietary iron that leads to hemoglobin insufficiency Pernicious anemia – unable to absorb vitamin B12 leading to an inadequate amount of RBCs Aplastic anemia – toxic chemicals or radiation damages red bone marrow Hemolytic anemia – toxic chemicals or radiation destroys erythrocytes Sickle cell anemia – defective gene that causes erythrocytes to be shaped abnormally Thalassemia – defective gene that causes a defect in hemoglobin and reduces erythrocyte life span Sickle cell animation  Destruction of RBC Damaged or worn cells are removed from the body by the spleen or liver - Macrophages phagocytize and destroy cells Hemoglobin is broken down into globin (polypeptides) – heme (iron containing group) which decomposes into biliverdin (greenish)…..while some is recycled!! Biliverdin is converted to bilirubin (orange) and excreted in bile – Increased billirubin in the blood causes?  White blood cells leukocytes protect against disease granulocytes – granular cytoplasm – neutrophils – eosinophils – basophils Agranulocytes – lack granules in cytoplasm – lymphocytes – monocytes Granulocytes  Neutrophils aka polymorphonuclear granulocytes or segs first WBC at site of infection – Phagocytize bacteria, fungi, some viruses 54% to 62% of leukocytes elevated in bacterial infections  Eosinophil bilobed nucleus contain coarse deep red staining granules defend against parasitic worm infestations 1% - 3% of leukocytes elevated in worm infestations and allergic reactions  Basophil deep blue granules is basic stain nuclei has 2 lobes release histamine – Promotes inflammation release heparin – Inhibit blood clotting less than 1% of leukocytes Agranulocytes  Monocytes largest blood cell kidney-shaped or oval nuclei leave bloodstream to become macrophages 3% - 9% of leukocytes elevated in typhoid fever, malaria, tuberculosis  Lymphocytes large spherical nuclei – thin rims of cytoplasm T cells B cells important in immunity - produce antibodies 25% - 33% of leukocytes decreased T Cells in AIDS  Functions of WBC Protect against infection in various ways: – phagocytize bacteria – produce proteins that destroy foreign particles Diapedesis: squeeze between cells of capillary wall – To enter tissue space outside the blood vessel – animation Inflammation delays spreading of microorganism  WBC Count leukopenia low WBC count typhoid fever, flu, measles, mumps, chicken pox, AIDS leukocytosis high WBC count acute infections, vigorous exercise, great loss of body fluids Whole vs. differential blood cell count  Blood Platelets thrombocytes arise from megakaryocytes small & lack nucleus helps control blood loss from broken vessels – Formation of platelet plug Blood Plasma  Blood Plasma straw colored liquid portion of blood – 92% water 55% of blood  Plasma also contains: 1) Plasma wastes Non-protein nitrogen substances (usually wastes) – urea, uric acid, creatinine, bilirubin 2) Plasma electrolytes – sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate, sulfate… Difference between plasma and serum?  3) Plasma Protein – 3 types Albumins most numerous plasma proteins & smallest 60% produced by liver help maintain osmotic pressure of blood Colloid osmotic pressure bind and transport molecules Free FA, hormones, certain drugs Fibrinogen produced by liver plays key role in blood clotting Largest of plasma proteins  Globulins – alpha, beta, gamma globulins Alpha and Beta globulins 1. produced by liver 2. important in transporting lipids and fat soluble vitamins around body Gamma Globulins (antibodies) 1. produced in lymph tissues 2. important in fighting infection 4) Gases & Nutrients Gases oxygen carbon dioxide nitrogen Nutrients amino acids simple sugars nucleotides lipids Carried as lipoproteins LDL & HDL  Hemostasis Stoppage of bleeding – Effective for smaller vessels Three mechanisms: – Blood vessel spasm – Platelet plug formation – Blood coagulation Formation of a blood clot  Blood vessel spasm Cutting or breaking a blood vessel stimulates the SM in its wall to contract - vasospams Caused by nervous system response to damage – and release of serotonin by platelets Also caused by reflex by pain receptors (in injured tissue)  Platelet Plug Formation triggered by exposure of platelets to collagen platelets adhere to rough surface to form a plug  Blood Coagulation animation Most effective hemostatic mechanism Causes blood clot formation Involves a series of reactions (cascade) Utilizes many clotting factors Vitamin K is necessary for clotting factors to function properly Major event is conversion of soluble plasma protein fibrinogen into insoluble threads of fibrin Extrinsic or intrinsic clotting mechanism  Blood coagulation depends on balance between pro-coagulants and anti- coagulants – Both found in blood – Normally anti-coagulants prevail and blood doesn’t clot  Extrinsic Mechanism **chemical outside of blood triggers blood coagulation Damaged cells release tissue thromboplastin Tissue thromboplastin activates clotting cascade  Extrinsic Mechanism calcium causes the release of prothrombin activator from platelets Prothrombin is converted into thrombin Thrombin converts fibrinogen to fibrin Fibrin threads stick to exposed damaged blood vessels. Meshwork traps blood cells and platelets. This produces a blood clot.  Extrinsic Mechanism prothrombin activator amount is directly proportional to the degree of tissue damage Blood clotting is self- initiating – a positive feedback system. Blood flow limits thrombin Anti-thrombin in blood & on vessel walls limit thrombin  Intrinsic Clotting Mechanism chemical inside blood triggers blood coagulation triggered by Hageman factor (found inside blood) triggered when blood contacts a foreign surface - collagen - toxins in blood - bacterial infection  Intrinsic Clotting Mechanism Cascade of activation in the presence of calcium – produces prothrombin activator Thrombin and fibrin are formed – as in the extrinsic pathway  Fate of blood cells After forming, blood clot retracts and pulls the edges of a broken vessel together Serum is squeezed through – Plasma minus clotting factors Platelet-derived growth factor (PDGF) stimulates smooth muscle cells and fibroblasts to repair damaged blood vessels Plasminogen is absorbed by fibrin. Plasminogen activator (from lysosomes in damaged tissues) converts plasminogen to plasmin. Plasmin digests blood clots  thrombus – abnormal blood clot in vessel embolus – blood clot moving through blood Embolism: embolus blocking blood flow – Named according to location Eg. Pulmonary embolism Hemophilia??  Prevention of Coagulation In a healthy cardiovascular system – Endothelium of blood vessel prevents spontaneous blood clot formation – Endothelial cells also produce protoglandin C (inhibits adherence of platelet to vessel walls) – As a clot forms fibrin absorbs thrombin (prevent the spread of clotting reaction) – Anti-thrombin (plasma protein) inactivates additional thrombin – Basophils and mast cells release heparin which interferes with the formation of prothrombin activator ***Leech treatment (hirudin)- anticoagulant ABO Blood Group  Blood Grouping ABO system – Type A blood Has only A antigens on the surface of RBC anti-B antibodies in plasma – Type B blood Has only B antigens on the surface of RBC anti-A antibodies in plasma – Type AB blood Has both A and B antigens on the surface of RBC NO antibodies in plasma – Type O blood Has NO antigens on the surface of RBC both anti-A and anti-B antibodies in plasma  Agglutination Results from the formation of an antibody/antigen complex – B antibodies bind with B antigen causing agglutination What would be the outcome of mixing type A blood with type B blood?  Transfusion Major concern in blood transfusion – Cells in the donated blood do not clump due to antibodies present in recipient’s plasma – If clumping occurs this leads to death. ****why?  ABO Blood Group Why are individuals with type AB blood called the universal recipients? Why are individuals with type O blood called universal donors?  Rh Blood typing system antigen sometimes found on RBC is the D antigen. – person with D antigen are Rh+ – if the do not have the D antigen they are Rh-. The only way a person may have antibodies against the D antigen: – is if they are Rh- and are exposed to Rh+ blood  sensitized  a Rh- person who is sensitized to the D-antigen (they have anti D antibodies) & becomes exposed to Rh+ blood a second time  agglutination occurs  Erythroblastosis fetalis or hemolytic disease of the new born animation