Blood Sample Chapter Key Notes

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This is one of the sample chapter of Aim MDS key notes.

This is one of the sample chapter of Aim MDS key notes.

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  • 1. BLOOD RED BLOOD CELLS: 1. most abundant cells of the blood Discussion notes/ my 2. contain a large quantity of carbonic anhydrase, an enzyme notes that catalyzes the reversible reaction between carbon dioxide (CO2) and water to form carbonic acid (H2CO3) 3. is an acid-base buffer diameter of about 7.8 micrometers and a thickness of 2.5 micrometers at the thickest point and 1 micrometer or less in the center. 4. RBCs have no nucleus and no mitochondria, ribosomes, ER and centriole. Since it does not contain mitochondria tricarboxylic acid cycle of the Krebs does not operate within it 5. cell membrane of RBC contains proteins a. Glycophorins (that extend through and through the membrane ) eg : blood group antigen b. Others like spectrin and actin are applied on the inner side of the cell membrane 6. RBC is biconcave due to a contractile protein “SPECTRIN” 7. Life span of RBC: 120 days. Number of RBCs dying daily is about 3.0 X 109 / kg body weight of the person. Advantage of biconcavity 1. increase in the surface area for the absorption of oxygen 2. ,because of the biconcavity, the erythrocyte can squeeze through the vessels. The disease where bico'ncavity of RBCs is lost is K/as “sperocytosis.” Or “elliptocytosis”
  • 2. www.aimmds.com PRODUCTION OF RED BLOOD CELLS rd 1. erythropoeisis starts in 3 week of intrauterine life Discussion notes/ my 2. Site of RBC synthesis notes rd a. In the 3 wk to 3rd mnth of embryonic life, primitive, nucleated red blood cells are produced in the yolk sac. (Intravascular erythropoiesis) b. During the3rd mnth to 5th of gestation, the liver is the main organ , but are also produced in the spleen and lymph nodes.(hepatic phase) c. Then, during the last month or so of gestation and after birth, red blood cells are produced exclusively in the red bone marrow.(myeloid phase) Extramedullary erythropoeisis: when there is necessity even yellow bone marrow, liver and spleen start erythropoisis. (Thymus never forms blood cells). Proerythroblast : pronormoblast = first in erythroid series Basophil erythroblast: Early normoblast Polychromatophillic erythroblast: intermediate normoblast (Hb appears) Late normoblast : orthochromatic erythroblast (pyknotic nucleus) Reticulocyte (nucleus extruded) Note : in earlier phase cytoplasm contains abundant RNA hence stains basophilic and with maturation Hb increases which is acidophilic. info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 3. www.aimmds.com HISTOLOGY OF THE BONE MARROW: BM consists of Discussion notes/ my 1. sinusoids ( capillaries with large diameter) notes 2. adventitious cell (that later covert into fat cells) 3. myeloid cells (that form the blood cells) Normal fat cell : blood cell ratio of the bone marrow is 1:1 The myeloid: erythroid ratio of the normal bone marrow is 3:1 REGULATION OF RED BLOOD CELL PRODUCTION: 1. Tissue Oxygenation 2. erythropoietin, a glycoprotein with a molecular weight of about 34,000.produced in Kidney (90%) and rest in liver (10%) (note : When both kidneys are removed from a person or when the kidneys are destroyed by renal disease, the person invariably becomes very anemic) 3. Maturation of Red Blood Cells—Requirement for Vitamin B12 (Cyanocobalamin) and Folic Acid a. Both of these are essential for the synthesis of DNA, b. the erythroblastic cells of the bone marrow, in addition to failing to proliferate rapidly, produce mainly larger than normal red cells called macrocytes, Pernicious Anemia.In pernicious anemia basic defect is in gastric atrophy thus parietal cells fail to produce Intrinsic factor (that binds Vit B12 i.e. extrinsic factor and make the latter available for absorption.) Lack of intrinsic factor, therefore, causes diminished availability of vitamin B12 info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 4. www.aimmds.com c. Deficiency of Folic Acid (Pteroylglutamic Acid). Folic acid is a normal constituent of green vegetables, some Discussion notes/ my fruits, and meats (especially liver). However, it is easily notes destroyed during cooking. d. Disease called sprue: abnormal absorption of Vit B12 and folic acid. Cases of pernicious anemia develop neurological symptoms but not the cases of folate deficience: both cause megaloblastic anemia (because Vit B12 deficiency causes demyelination of nerves) 4. Vitamin B6 and Vitamin C: a. Vitamin C is concerned with the absorption of iron. 5. Iron: a. Concerned with the formation of hemoglobin RED CELL INDICES: RBC count Adult men: 5.5 million/ cu mm Females: 4.8 million/ cu mm Hb concentration 15 gm / 100 ml of blood Packed cell volume : blood + 45 per 100 ml anticonaglant is centrifuged, the Ie 45% volume of the packed cell is PCV Mean corpuscular volume (MCV) 90 cub µ = Mean corpuscular Hb : Hb in 30 pg each RBC Hb in gm / liter of blood = RBC count in million/ cmm info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 5. www.aimmds.com Mean corpuscular Hb 33.3 gm/100 ml of cells Discussion notes/ my concentration: amount of Hb notes present on 100 ml of RBC The intensity of erythropoiesis can be judged by the count of the % of reticulocyte in the blood. Count > 3 % indicate increased erythropoiesis Count < 0.5 % indicate less than normal erythropoiesis . FORMATION OF HEMOGLOBIN 1. Begins in the proerythroblasts and continues even into the reticulocyte stage of the red blood cells 2. Four pyrroles combine to form protoporphyrin, which then combines with iron to form the heme molecule. 3. Finally, each heme molecule combines with a long polypeptide chain, a globin synthesized by ribosomes, forming a subunit of hemoglobin called a hemoglobin chain 4. The different types of chains are designated alpha chains, beta chains, gamma chains, and delta chains. info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 6. www.aimmds.com Hb Type formula Discussion notes/ my hemoglobin in the HbA two alpha chains and notes adult human(98%) two beta chains hemoglobin in the HbA2 Two alpha two delta adult human(2%) chains Fetal Hb HbF Two alpha two gamma chains Sickle Hb HbS amino acid valine is substituted for glutamic acid at one point in each of the two beta chains 5. Hemoglobin A has a molecular weight of 64,458. (~ 65-67 KD) 6. Four molecules of oxygen (or eight oxygen atoms) that can be transported by each hemoglobin molecule. In sickle cell anemia the amino acid valine is substituted for glutamic acid at one point in each of the two beta chains. When this type of hemoglobin (Hb S) is exposed to low oxygen it forms elongated crystals (tactoids) inside the red blood cells resulting in the sickling of the RBC.t hese sicled RBCs rupture when they pass through the narrow capillaries. 7. Hb has 250 times more affinity to CO than O2 IRON METABOLISM 1. The total quantity of iron in the body averages 4 to 5 grams, about 65 per cent of which is in the form of hemoglobin. 2. Iron in absorbed in ferrous state where as it is present in food in ferric state; ascorbic acid (vit c ) being a reducing agent converts ferric iron to ferrous iron 3. it is absorbed in the upper part of the intestine. info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 7. www.aimmds.com 4. When iron is absorbed, it immediately combines in the blood Discussion notes/ my plasma with a beta globulin, apotransferrin, to form transferrin, notes which is then transported in the plasma to the bone marrow for the formation of RBCs and to tissues for formation of other iron containing compounds. 5. After the death of RBC , iron is extracted and retained as “Ferritin” (ferric state) in Reticuloendothelial system. (thus ferritin comes from dead RBCs and not from food) 6. Ferritin is stored within the case of a protein apoferritin. 7. when iron is excessive it forms hemosiderin (part of protein casing is lost) 8. iron in Hb is in ferrous state, …. And even after taking up the oxygen remains in ferrous state. The enzyme that prevents the oxidation is methemoglobin reductase with NADH Methemoglobinemia: iron of Hb is oxidized to ferric form and oxygen cannot release itself from such Hb Iron requirement: 1. iron is deposited in fetal body in the last phase of intrauterine life …hence premature babies are susceptible to iron deficiency 2. Iron req in adult as low as 1 mg increases in women of reproducing age. 3. Iron overload : Bronze diabetes = excess hemosiderin in the body info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 8. www.aimmds.com FATE OF HB: Discussion notes/ my notes normal bilurubin Conc : 0.5 to 1 mg/dl Glucoronyl transferase catalyses conjugation: when absent : Criggler najjar syndrome info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 9. www.aimmds.com porphyria, porphyrinuria: defective heam synthesis Thalassemia : (α or β chain defect ): refer O Path for details Discussion notes/ my Hb D Punjab : mild hemolytic anemia in 2% Punjab population notes AMEMIAS: Iron deficiency anemia: microcytic hypochromic an. Vit B 12 and folate deficiency : Megaloblstic anemia, macrocytic hemolytic anemia: Normocytic , increased bilurubin Aplastic anemia : reticulocyte count drops to “Zero” polycythemia :increase RBC count a. primary : Polycythemia vera, unknown eitiology (erythropoietin concentration in low) b. secondary : disease(eg. Emphysema) increased erythropoietin increased RBC info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 10. www.aimmds.com THE LEUCOCYTES: 1. about 7000 (4500- 11000) white blood cells per microliter of Discussion notes/ my blood. notes 2. normal percentages of the different types (differential count) based on Romanowskis stain. Stain components: Azure B= basic that combines with acidic material and Eosin Y =acidic that combines with basic 3. Variant of Romanowskis stain: Wright stain , Leishman stain , Giemsa stain , Jenners stain Exercise: Diagram WBCs Neutrophil neutrophil lobes: several: young neutrophil less lobes number Arneth count: ratio between different lobed nutrophils More young cells : shift to left and older cells shift to right Shift to left : infection Shift to right megaloblastic anemia Eosinophils: Bi-lobed nucleus, coarse granules Basophil S shaped nucleus, coarse basophilic granules Monocytes: Largest WBC, ovoid nucleus very often indented (horse shoe shape) Non granulocyte but has fine granules lymphocyte : small and large info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 11. www.aimmds.com functions: Discussion notes/ my 1. immunity and protection notes 2. neutophils : first line of defence; also called microphage 3. Monocytes: second line of defence 4. Eosinophils : antiparasitic, heve little or no activity against bacteria 5. applied physio: leucocytosis: >11,000 WBCs/cu mm of blood i. neutrophilic leucocytosis : acute bacterial infection ii. eosinophilic leucocytosis: parasitic infection THE PLASMA PROTEINS: 1. Blood = plasma + formed elements 2. Serum= plasma – fibrinogen 3. plasma contains 6-8 gms protiens/100ml 4. the proteins of plasma: a. albumin: 4 gms/dl b. globulin: 2.5 gms/dl Thus in health albumin: glubulin ratio is 1.7 c. fibrinogen: 0.3 gms/dl d. prothrombin 0.03 gms/dl 5. albumin maintains colloidal osmotic tension of the blood Thus hypoalbuminaemia leads to retension of water in the tissues: edema 6. Oncofetal antigens: some proteins are synthesized only in fetus and their levels drop later, if in the post natal life person develops cancer these proteins appear again and hence called as Tumor markers: a. eg: a. Carcinoembryonic antigen 1. b. Alpha fetoprotein info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 12. www.aimmds.com BLOOD GROUPS RBC contain Discussion notes/ my 1. Agglutinogens (antigen) that react with specifi agglutinins notes (antibodies) in plasma a. The agglutinogen are present on the surface of the RBCs and are chemically glycoproteins. b. the agglutinins are plasma globulins and are either IgM or IgA type of immunoglobulins 2. there are various blood grouping systems, the important ones are ABO system, Lewis, Duffie, Lutheran and so on. 3. The blood grouping systems: The ABO blood group system is widely credited to have been discovered by the Austrian scientist Karl Landsteiner Applied: 1. ABO blood group incompatibilities between the mother and child does not usually cause hemolytic disease of the newborn (HDN) because antibodies to the ABO blood groups are usually of the IgM type, which do not cross the placenta; however, in an O-type mother, IgG ABO antibodies are produced and the baby can develop ABO hemolytic disease of the newborn. info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 13. www.aimmds.com Rh Factor: 1. The term Rhesus (Rh) blood group system refers to the 5 Discussion notes/ my main Rhesus antigens (C, c, D, E and e) as well as the many notes other less frequent Rhesus antigens. The terms Rhesus factor and Rh factor are equivalent and refer to the Rh D antigen only. 2. Individuals either have, or do not have, the Rhesus factor (or Rh D antigen) on the surface of their red blood cells. This is usually indicated by 'RhD positive' (does have the RhD antigen) or 'RhD negative' (does not have the antigen) suffix to the ABO blood type Some facts about blood group antigens and antibodies: Anti A and anti B antibodies are produced by the body without being challenged by the antigens, such antibodies are called as naturally occurring antibodies. Secondly as seen earlier anti- A is present in individuals which do not have A antigen in their RBC, such antibody which cab react with the antigen not present in a person in whom these antibodies are present is called alloantibody or iso antibody. On the other han Rh antibody develops only after the exposure to antigen, thus they are immune antibodies. Cold and warm antibodies: o Antibodies that react best at temperature between 5-20 are cold antibodies and those which react best at human body temperature are warm antibodies. Most of the blood group antibodies are of IgM variety which are cold antibodies thus they do not react at body temperature. The well known exceptions are Anti-A and anti- B which, inspite of being IgM type are warm antiboidies While Rh-antibodies are initially IgM type and later they switch to IgG type (can cross the placenta), and are warm antibodies. info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 14. www.aimmds.com In mismatched blood transfusion only the donor’s erythrocytes Discussion notes/ my are destroyed but the recipient erythrocytes are not harmed notes because during transfusion the donor’s antibodies get mixed with recipient and get diluted thus ineffective. PLATELET, HEMOSTASIS AND COAGULATION: 1. normal platelet count : 1,50,000 to 4,00,000/cmm(μl) 2. critical count of platelet: 40,000 below which hemorrhagic manifestation occurs 3. morphology: a. non nucleated (no DNA or RNA) b. disc like when inactive and on activation become spherical c. synthesized in RBM from megakaryocytes, (a single megakaryosite can give rise to 1000 platelets) Bone marrow contains only one day reserve for the platelets so humans prone to develop thrombopenia d. Life span : 7 to 12 days Platelet contents granules Alpha • Fibronectin granules • Platelet factor 4 • Platelet growth factor • Von willibrand factor vWF derived from two sources vascular endothelium and platelets • Thrombospondin:Thrombospondin acts as bridge between platelets and between platelet and fibrinogen. Dense • ATP, ADP granules • serotonin Glycogen granules info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 15. www.aimmds.com 1. tubules of platelet : ++ a. open tubules (Ca from ECF can enter platelets Discussion notes/ my from here when needed) notes ++ b. dense tubules (store Ca ions) 2. two contractile elements a. actin b. myosin 3. platelet membrane: a. outer glycocalyx b. inner lipoprotein 4. Genesis: derived from Megakaryocytes HEMOSTASIS AND COAGULATION Clotting : three stages a. Stage I: formation of prothrombin activator b. Stage II: prothrombin activator converts prothrombin to thrombin c. Stage III: thrombin converts fibrinogen to fibrin Formation of prothrombin activator: 2 major pathways: a. The intrinsic pathway: triggered by activation of Hageman factor (XII); Factor XII could be activated even by contact with glass henceaka Glass contact factor b. The extrinsic pathway: triggered by release of tissue factor (TF) info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `
  • 16. www.aimmds.com Discussion notes/ my notes Vitamin K is necessary for liver formation of five of the important clotting factors: 1. prothrombin, 2. Factor VII, 3. FactorIX, 4. Factor X, 5. and protein C. Liver synthesizes: Factor V, VII, IX, X, prothrombin, fibrinogen and anticoagulants thrombin, antithrombin III and protein C Disseminated Intravascular Coagulation: results from the presence of large amounts of traumatized or dying tissue in the body that releases great quantities of tissue factor into the blood.usually in septicaemia (due to endotoxins); d. These patients also show increased bleeding tendency as lots of coagulation factors are used up THE TESTS OF COAGULATION: The partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT or APTT) : is a performance indicator measuring the efficacy of both the "intrinsic" (now referred to as the contact activation pathway) and the common coagulation pathways Deficiencies of factors VIII, IX, XI and XII and rarely von Willebrand factor (if causing a low factor VIII level) may lead to a prolonged aPTT prothrombin time (PT) which measures the extrinsic pathway. The reference range for prothrombin time is usually around 12–15 seconds; the normal range for the INR is 0.8–1.2. PT measures factors II, V, VII, X and fibrinogen. Clotting Time: collect blood in a chemically clean glass test tube and then to tip the tube back and forth about every 30 seconds until the blood has clotted. By this method, the normal clotting time is 6 to 10 minutes. info@aimmds.net aimmds@gmail.com Mb: 099451 06051 `