BLOOD

1. BLOOD BY Dr shamshad Begum .A.Loni Lecture notes

2. Composition of Blood

3. Constituents of blood Formed elements 45% Plasma 55% RBCs 5 million/cumm (µl) 91.5% water 7% gm% proteins 3.8gm % albumin (54%) 2.7gm% globulin (38%) 0.5gm % fibrinogen (7%) WBCs 10,000/cumm (µl) neutrophils 60-70% Eosinophils 2-4% monocytes 3-8% lymphocytes 25-30% basophils 1% 1.5% Electrolytes Nutrients Gases Regulatory substances Waste products Platelets 140-400000/µl

4. Constituents of blood

5. Physical characteristics of blood • Thicker than water with a Specific gravity around 1.58 • pH 7.35-7.45 • Colour: bright red when oxygenated • dark red when de-oxygenated • 8% body weight • 20% of ECF • Volume about 5 liters(70 ml/Kg body wt.) • Sampling by venipuncture; finger pick/heel prick • arterial puncture

6. Functions of blood 1. Transportation of respiratory gases(O2 & CO2); nutrients ; hormones; waste products 2. Regulatory: body temperature; pH 3. Protection against disease (immune functions); against blood loss (coagulation)

8. Erythrocyte Function • Erythrocytes are dedicated to respiratory gas transport • Hemoglobin reversibly binds with oxygen and most oxygen in the blood is bound to hemoglobin • Composition of hemoglobin • A protein called globin • made up of two alpha and two beta chains • A heme molecule • Each heme group bears an atom of iron, which can bind to one oxygenmolecule • Each hemoglobin molecule thus can transport four molecules of oxygen

9. Leukocytes (WBCs) Neutrophils • Neutrophils are our body’s bacteria slayers • Protect the body from infectious microorganisms • Can leave capillaries via diapedesis • Move through tissue spaces (amoeboid motion) • Many are phagocytic (possess numerous lysosomes) • Leukocytosis – WBC count over 11,000/mm3 • Normal response to bacterial or viral invasion • Leucopenia- a decrease in WBC count below 4,800/mm3 • Leukemia - a cancer of WBC

10. Eosinophils • Eosinophils account for 1–4% of WBCs • Have red-staining, bilobed nuclei • Have red to crimson granules • Function: • Lead the body’s counterattack against parasitic infections • Lessen the severity of allergies by phagocytosing immune complexes (ending allergic reactions)

11. Granulocytes: Basophils • Account for 0.5-1% of all WBCs • Have U- or S-shaped nuclei with two or three conspicuous constrictions • Are functionally similar to mast cells • Have large, purplish-black (basophilic) granules that contain histamine • Histamine – inflammatory chemical that acts as a vasodilator and attracts other WBCs (antihistamines counter this effect)

12. Agranulocytes: Lymphocytes • Account for 20-25% or more of WBCs and: • Have large, dark-purple, circular nuclei with a thin rim of blue cytoplasm • Are found mostly enmeshed in lymphoid tissue (some circulate in the blood) • Most important cells of the immune system • There are two types of lymphocytes: T cells and B cells • T cells - attack foreign cells directly • B cells give rise to plasma cells, which produce antibodies

13. Monocytes • Monocytes account for 3–7% of leukocytes • They are the largest leukocytes • They have purple-staining, U- or kidney-shaped nuclei • They leave the circulation, enter tissue, and differentiate into macrophages

14. Platelets • Platelets are fragments of megakaryocytes • Their granules contain serotonin, Ca2+, enzymes, ADP, and platelet-derived growth factor (PDGF) • Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels • Platelets not involved in clotting are kept inactive by Nitric Oxide (NO) and prostaglandins

16. Red Blood Cells (erythrocytes) • No. 4-5 million/cumm (μL) • Size 7μ, bi-concave discs • No nucleus: can not reproduce = More surface area & center becomes thinner (biconcave):- More O2 can be carried- Squeeze into narrow capillaries- Allow O2 & CO2 Diffusion • NO mitochondria: ATP by anaerobic means (advantage: do not use up O2 they carry) • RBCs carry blood group antigens (A,B, O) on their cell membranes Life span 120 days • Destroyed in the body by RE cells: by products are recycled (mostly at Spleen)

17. Coagulation of blood • It is Actions of the protein coagulation factors to form fibrin in response to injury to the blood vessels • Liquid Blood changes into a solid

18. Hemostasis: Consists of three stages • Primary Hemostasis • Process of blood clotting in response to injury • blood vessels (vasculature) and platelets play important role • Primary Hemostatic plug temporarily arrests bleeding. • Insoluble fibrin strands deposit on the initial plug to reinforce and stabilize. • The fibrin originates from soluble plasma proteins. • Secondary Hemostasis • Actions of the protein coagulation factors form fibrin in response to injury • At this time, blood has changed into a solid state • Fibrynolysis • Clot is removed following healing of wound

19. Categories of Hemostasis Secondary Hemostasis Primary Hemostasis • Primary • Vascular System • Endothelia • Sub endothelia/collagen • Platelets • Secondary • Coagulation System • Plasma Proteins • Cells: Platelets • Fibrinolytic System • Plasma proteins • Cells: Platelets, Endothelia

22. Coagulation Cascade Pathways • Pathways to achieving a stable blood clot • Extrinsic • Intrinsic • Common

23. ABO Blood Groups • The ABO blood groups consists of: • Two antigens (A and B) on the surface of the RBCs • Two antibodies in the plasma (anti-A and anti-B) • Agglutinogens and their corresponding antibodies cannot be mixed without serious hemolytic reactions

24. ABO Blood Groups

25. Rh Blood Groups • Presence of the Rhagglutinogens on RBCs is indicated as Rh+ve85% of population is + • Lack of antigen indicated as Rh–ve in 15% of popn. • Anti-Rh antibodies are not spontaneously formed only in Rh– individuals • However, if an Rh– individual receives Rh+ blood, anti-Rh antibodies form • A second exposure to Rh+ blood will result in a typical transfusion reaction

26. Blood Typing • Blood typing involves determination of the antigens present on an individual’s RBCs • The two most common blood typing systems used are the A-B-O method and the Rh method • type A blood – contain “A” antigen on RBCs • type B blood – contain “B” antigen on RBCs • type AB blood – contains both A and B antigens • type O blood – contain no A or B antigens • Rh+ blood – contain Rh antigen • Rh- blood – no Rh antigen

27. Blood Typing • When serum containing anti-A or anti-B agglutinins is added to blood, agglutination will occur between the agglutinin and the corresponding Agglutinogens • Positive reactions indicate agglutination

28. PLATELET COUNT (CBC) NORMAL 100,000 - 400,000CELLS/MM3 < 100,000Thrombocytopenia 50,000 - 100,000Mild Thrombocytopenia < 50,000Sever Thrombocytopenia

29. Clotting time • Clotting time was used as a screening test to measure all stages in the intrinsic coagulation system and to monitor heparin therapy • . • Severe hemophilia, a fibrinogenemia, and sever fibrinolytic states cause a prolonged clotting time, as do circulating anticoagulants ( inhibitors), and heparin

30. Clotting Time - Slide Method(Intrinsic) • The surface of the glass tube initiates the clotting process. This test is sensitive to the factors involved in the intrinsic pathway • The expected range for clotting time is 4-10 min.

31. Normal HB level Male: about 13-15 gm% Female about 12-14 gm% Clinical implications Anemia means a deficiency of Hb which can be caused by either too few RBCs or too little Hb in the cells. For diagnosis of anemia: Hemoglobin <13.0 g/dl for males < 12.0 g/dl. for females

32. Rh typing • Another group of antigens found on the RBC of the most of the people is the Rh factor (named for the rhesus monkey ) • There are number of different antigens in this group, • This Rh antigen is termed as D and is often indicated as RH D + or _ve