1. Basic Haematology.pdf

CHAPTER I BASIC HEMATOLOGY connective...

CHAPTER I BASIC HEMATOLOGY connective It is a special1zed ffuid atoloEY is a branch of science which deals with the study ofblood. elements such as the of corpuscles and platelets, and plasma. Blood consists of formed on iSUng Cells (WBCs) and the thrombOcytes or Red Blood Cells (RBCs). leucocvtes or White Blood ynrocytes bluc haemolymph of crustaceans, Oplatelets. Blood shows great variations in different animals for example, to a chlorocruorin), and and blood of some worms (due pigment ofAnnelids vertebrates, green colorless blood of Amphioxus, Leptocethalus, insects and myriapoda. Composition of blood colored viscous fluid in vertebrates including man. The blood consists of a suspension of d red The plasma constitutes 55% O1 the called the corpuscles (RBCs, WBCs and platelets) in the plasma. CCus 45%. The ratio of the red blood Oa numan blood whereas the blood corpuscles make up the remaining haemotocrit. The general composition opuscles to the plasma is expressed as the haemotocrit value or of whole blood is as follows:- A) Cells: RBC, WBCs and platelets. B) Plasma: Water 92%, remaining 8% consists of: a) Proteins- Serum albumin, serum globulin, fibrinogen, prothrombin. neutral b) Organic substances other than proteins- glucose, amino acids, fats, phospholipids, fats, cholesterol and cholesteroids. C) Inorganic substances- chlorides, carbonates and bicarbonates of Na, K, Ca and Mg. d) Various antibodies, hormones, enzymes, etc. e) Waste materials- urea, uric acid, ammonia, creatinine, xanthene etc. Colorcompounds-The yellowcolor ofplasma is due to small amounts ofbilinubin, carotene, and xanthophyllin. When freshly shed, blood is red thick and opaque due to different refractive powers of the plasma and red blood cells. Blood is slightly alkaline having apH of74,with specific gravity ranging from 1.005 to 1.060 and has the capacity to clot. Functions of blood: 1) Transport ofrespiratory gasses- Blood carries 02 from the lungs to the tissues and CO2 from the tissues to the lungs. 2) Transport ofnutrients- It carries digested food material from the intestine to the tissue cells. It also carries nutritive material from one part of the body to the other. 3) It acts as a medium oftransport for hormones, vitamins, enzymes, etc. 4) carries waste productsofcellular activity and brings them to the organs of excretion through kidneys. 5) Helps in the protection of the body through celular as well as humoral (production of antibodies) defense mechanism. 12  1.1 PLASMA contains 92 o of water The plasima resembles the tissue fluids in composition and general appearance. It and 8% ofdissolved substances such as proteins, inorganic and organic substances, dissolved gasses, antibodies, enzymes, hormones, waste materials and electrolytes. INORGANIC CONSTITUENTS OF THE PLASMA for The inorganic constituents of plasma include various salts present in different concentrations necessary the proper functioning ofcells. NaCl is responsible for maintaining the osmotic pressure of the tissue cells. Na- bicarbonate and Na- phosphateneutralize the acids fomed in metabolic processes and thus maintain the normal body alkalinity. The osmolality ofthe extracellular fluids (and also ofthe intracellular fluids, since they remain in osmoti The equilibrum with the extracellular fluids) is determined almost entirely by the fluid Nat concentration. so that the glucose and urea are non-ionic osmolar solutes normally present at 3% ofthe total osmolality, Nat2ion of the extracellular fluid controls 90% to 959% ofthe effective osmotic pressure The concentration ofcalcium in the plasma varies between 9.00 to 10.0 mg%. The Ca levels in the different plasma are mainly regulated by the parathyroid hormone. The Ca*present in plasma is of three forms 1) calcium combined with the plasma proteins (approx 41% 1.Omm/litre). 2) Ca combined with othersubstances like citrates phosphates (approximately 9% 0.2 mm/litre) 3) lonized Ca (approx. 50%). The average phosphate ions in the blood is 2.5 to 4.5 mg/100 ml The major proportion ofiron in the body is in the form of haemoglobin. ( 12-17.5 gms/dl ) Extracellular Magnesium concentration is very litle. A few elements are present in such small quantities that they are called as trace elements such as lodine, Copper, Zinc, Cobalt, Manganese and Fluorine. Organic constituents other than proteins: The organic matter constitutes about 0.1 % oftotal dissolved components in the plasnma. The blood plasma contains materials in the form ofSugar(80 mg/ 100ml ofblood), Urea 25 mg%. Ceatinine (1.5 mg %), Cholesterol (154mg %), ete. Respiratory gases such as 0, and CO, are carried by blood. Nitrogen is merely dissolved in plasma (79 to 80 %). Plasma proteins In the embryonic condition the plasma proteins areproducedbythe mesenchymal cells. The albumin fraction is formed first followed by others later. In the adult all plasma proteins are manufactured by the liver. Globu- lins are synthesized in the liver and relcased from the disintegrated cells oflymphaticsystem and lymphocytes. Vitamin K helps in the formation of prothrombin. The plasma proteins are used up every 14 days. The plasma proteins amount to 7-8 gm/l100ml of blood including serum albumin, serum globulin (a. B.y) and fibrinogen. These proteins give viscosity to the plasma and help maintain the blood pressure. Serum albumin forms a major component and constitutes about 4.7 to 5.7% ofthe total plasma proteins. It is made up ofa single polypeptide chain with molecular weight of 69,000 Da. It is soluble in distilled water and can be precipitated by saturated ammonium sulphate. Serum albumins can be coagulated by heat. The serum albumins are majorly synthesized in the liver. The primary function of the albumins (and other proteins to a lesser extent) is to maintain osmotic pressure at the capillary membrane. Serum globulins-It constitutes about 1.3% to 2.5% ofthe total plasma proteins. They are not soluble in water but dissolve in saline solution. Their molecular weight varies from 90,000 to 13,00,000 Da. Serum globulins can be separated by electrophoresis into 3 fractions nanmely a globulins, B globulins and y globulins. The a and B globulins detemine the blood groups while the globulins constituteantibodies. Globulins are coagulated at about 70°C. 13  álglobulin consists aGlobulins(ál and á2HTheir molecular weight range from 41,000 to 2,00,000Da. The steroids, in the transportoflipids, with bilinubin and another helps Sycoprotein. á2 pioh Combines hepatoglobulins etc. The á globulins are macroglobulins, Dulins consists of á2 concemed with etc. with the transport of adrenal cortical hormones lipids copper Pglobulins in thyroxin, the also help in transport of iron and copper. a globulins. Th amage oflipid, steroid and carotene and Lus-Theirmolecularweights ranges from1,50,000to 1,90,000Da.Antibodiesbeong l t constitutes about 0.3%of the total olasma proteins. Itis globulin in nature and has a molecular clot 000 Da. It is coagulated at about 56°C. Fibrinogen performs important Tuncioo Sd t is closely bound to prothrombase. Fibrinogen is also associated with Calcium anu um. When these ions are separated from fibrinogen it loses the property ofclotting. Fibrinogen is Iormed in the liver. Occasionally the quantity of circulating fibrinogen decreases in liver aiseast cetary sources ofplasma proteins are meat, casein, gelatin wheat etc. The plasma proteins can de Casiuly and rapidly manufactured by the body from amino-acids and tissue manufacture of prothrombin in the liver. proteins. Vitamin k neps nuthe u Functions of plasma 1) proteins: They act as a medium in which the blood 2) They maintain the osmotic corpuscles are protected from damage. 3) Fibrinogen forms insoluble pressure of blood. fibrin which forms the clot. 4 Plasma proteins act as buffers and prevent changes in the reaction ofblood. (pH of blood is mantainea constant). )globulins are the immunoglobulins protecting our body against bacteria and toxins. Their amount increases during infectious diseases. 6) 0 and ß globulins are responsible for blood groups. 7) They help in growth of new cells and repair the damaged ones. 0 h eleucocytes prepare substances called trephones from theplasma proteins which are necessary for the nourishment of tissue cells. 9) They help in the carriage of C02 by forming carbamino compounds. Origin of plasma proteins: n the embryonic condition the plasma proteins are produced by the mesenchymal cells. The albumin first traction is fomed by others later In the adult all plasma proteins are manufactured by the followed liver. Globulins are synthesized in the liver and released from the disintegrated cells of lymphatic system and lymphocytes. Vitamin K helps in the formation ofprothrombin. The plasma proteins are used up every 14 days. 1.2 Haematopoiesis Stem cells are undifferentiated embryonic cells that can differentiate into other cell types. They are said to be pluripotent and tipotent. The stem cells develop into blood cells through a process called haematopoiesis. The stem cells that develop in RBCs and WBcs are called haemocytoblasts or haemopoietic stem cells (HSC). In humans, haematopoiesis begins in the embryonic yolk sacduring the first week of development. Yolk sac stem cells differentiate into primitive erythroid cells that contain embryonic haemoglobin. By the third month of gestation, haematopoietic stem cells migrate from the yolk sac to the fetal liver and subsequently colonize the spleen. The liver and spleen play major roles in haematopoiesis from the third to the seventh months of gestation. Later the differentiation of HSCs in the bone marrow becomes the site of haematopoiesis. 14  All functionally specialized mature blood cell arise from an HSC. Due to self renewal capacity of the HSCs, they are maintained at stable levels throughout the adult life. However when there is an increase demand for haematopoiesis, a multipotent stem cell differentiates along two pathways, giving rise to either a lymphoid progenitor cell or myeloid progenitor cell. Progenitor cells do not have selfrenewed property and are thus committed to a particular cell lineage. 1) Lymphoid progenitor cell give rise to B-lymphocytes, T-lymphocytes and null cells. The null cells are oftwo types namely natural killer cells and killer cells. 2) Myeloid progenitor cells generate progenitors of red blood cells (erythrocytes), neutrophils, ecosinophils, basophils, monocytes, mast cells, dendritic cells and megakryocyte (platelet generating cells). In bone marrow, haematopoietic cells and their descendants grow, differentiate and mature on mesh like support of stromal cells, which include fat cells, endothelial cells, fibroblasts and macrophage. Stromal cells influence the differentiation of haematopoieticstem cells by provinga haematopoietic inducing microenvironment (HIM) consisting ofa cellular matrix and factors that promote growth and diffërentiation. Multipontetial hematopoietic stem cell (Hemocytoblast) common myleoid progenitor Common lymphoid progenitor Erythrocyte Mast cell Small lymphocyte Natural Killer cell Myeloblast (Large granular lymphocyte) Megakaryocyte T lymphocyte B lymphocyte Basophil Neutrophil Eosinophil Monocyte Plasma cell Thrombocyte Macrophage Fig. 1.1 Regulation of haematopoiesis a) Programmes cell death (Apoptosis). It is an induced and ordered process in which the cell actively participates in bringing about its own death. It is a critical factor in the homeostatic regulation of many types of cell populations including those ofthe haematopoietic system. Each ofthe leukocytes produced by haematopoiesis has a characteristic life span and then dies by programmed cell death. In the adult human, there are about 5 x 100 neutrophils in the cireulation. These cells have a life spanofonly one day before programmed cell death is initiated. A stable number of these cells are maintained by constant neutrophils production. Programmed cell death also plays a role in maintaining proper number of haematopoietic progenitor cells for erythrocytes and various types ofleucocytes. 15  stem cell Multipontetial hematopoietie (Hemocytoblast) Common myeloid progenitor Proerythryoblast Myeloblast (Pronompblast) Basophilic B promyleocyte N erythroblast promyleocyte E promyleocyte Monoblast B myleocyte N myleocyte E myleocyte Promonocyte Polychromatic erythroblast B Orthochromatic metamyleocyte N metamyleocyte E metamyleocyte erythroblast (Normoblast) Polychromatic B band N band E band erythrocyte (Reticulocyte) Erythrocyte Basophil Neutrophil Eosinophil Monocyte (Red blood cell) Granulopoiesis Monocytopoiesis Erthropoiesis Mast cell Macrophages Myleoid dendric cell Fig. 1.2 Haematopoiesis 16  Erytropoiesis / Development and maturation of RBC Fig. 1.3 Development and maturation of RBC It is production ,development and maturation ofRBCs. In early embryonic stage RBCs are produced by yolk sac ,later on they are produced by liver and spleen. Lymph nodes also take part in RBC production. After birth RBC are produced by bone marrow( Myeloid tissue).During early phase oflife all bones produce RBCs.After age of20 yers, red bone marrow of the bones is replaced by yellow marrow (Fibrous).From then cells are produced only by membranous bones such as ribs, vertebrae, stermum.pelvs etc. There are two theories about origin of RBCs.: 1. Intra vascular and 2. Extra vascular According to intravascular theory RBCs are formed only intravascularly. for According to extra-vascular theory, an extra vascular cells called Haemocytoblast is responsible production of RBCs I. Haemocytoblast-These cells are formed from primordial stem cells, capable of multiplication, 18- 23 u in diameter.Large molecules, thin basophilic cytoplasm. They proliferateand give rise to next stage i.e. proerythroblast. I Proerytroblast-I develops from heamocytoblast, 14-19 u in diameter ,basopfilic eytoplasm.Iarge nucleusand distinct nucleolus,reticulum of fine chromatin,haemoglobin is absent.Actively multiplies into next stage i.e Early erythroblast or normoblast. III. Early erythroblast/ Normoblast- It is smallerin size, 11-17u in diameter, nucleus and chromatin mare more denser, nucleoli is absent or rudimentary.lt actively multiplies into next stage i.e, Late erythroblast or intermediate normoblast. IV. Late erythroblast/ intermediate normoblast -The size still remains smaller which is 10-14 u.nucleus is more condensed and often acentric ,Hb appears at this stage.cytoplasm polychromatic which changes into next stage i.e. Normoblast.As the cell matures,more and more Hb is synthesized and condensation of nuclear chromatin material takes place. V. Normoblast - The size is more reduced i.e.7-10 u, which is slightly larger than matured RBCs. Nucleus is very dense ( in staining takes up deep stain and termed as ink spot nucleus).more and more Hb is produced. further maturation of normoblast involves complete loss ofnucleus. Amount ofHb increases as nucleus disappears.Normoblast after loss of nucleus passes through next stage ie reticulocyte. VI. Reticulocyte- It shows net like structure or reticulum in cytoplasm which are remains of basophilic cytoplasm.Atthis stage,cell enters into circulation. Reticulum disappears completely and cell matures as erythrocyte. of 2 u., devoid of nucleus and VII. Erythrocyte It has diameter of 7.5 u and has thickness at edges - Hb. The normal life span oferythrocyte is presence ofnucleus.Cells are not capable to synthesize about 120 days.The cells are thinner at centre and biconcave in shape. 17  stem cell Multipontetial hematopoietic (Hemocytoblast) Cominorn Tymphoid Common myleoid progenitor progenitor Megakaryoblast roerythryoblast Myeloblast Lymphoblast (Pronomoblast) Basophilic B promyleocyte N promyleocyte E promyleocyte Monoblast Promegakaryocyte erythroblast B myleocyte Nmyleocyte E myleocyte Promonocyte Prolymphocyte Polychromatic erythroblast Megakaryocyte Orthochromatie erythroblast B metamyleocyte N metamyleocyte E metamylcocyle (Normoblast) o' B band N band E band Polychromatic erythrocyte (Reticulocyte) Natural killer cell Thrombocyte Basophil Neutrophil Eosinophil onocyte Monocytopoiesis| Large granular (Platelets) Erythrocyte Granulopoiesis Small ymphocyte) Thrombopoiesis (Red blood cell) lymphocyte (4) Erthropoiesis ymphocytelymphocyte Lymphopoiesis ymphoid dendritic Macrophage Mycloid cell (3) dendntic cell (3) Plasma cell Fig. 1.4 Production of blood cells Leucopoiesis /Development and maturation of WBC:- Life span of various WBC is difficult to determine since these cells enter the tissue leave the blood vascular spaces. The WBCs remain in circulation system to passing into lymphoid organs again return into circulation. only for about 24 hrs. Many Some cells are lymphocytes after liver, spleen and other reticulo-endothelial removedby phagocytosis within constant figure by the formation ofnew system. The numbers of WBCs in circulation are kept at a cells. Granulocytes are formed in while agranulocytes are formed in the the bone marrow i.e. lymphoid organs. In the foetus, blood cells are formed inMyeloid, mesenchyme, blood vessels, liver, spleen and lymph nodes. But after birth yolk sac. main haemopoietic tissue. bone marrow constitutes the Differentiation and maturation of WBCs involves:1) Development and accumulation 2)An increase in the size of 3) Progressive reduction in size of the cell. The of specific granules. nucleus. development in order of differentiation from the stages of granulocyte Myelocyte, 4) Metamyelocyte and 5) Granular haemocytoblast are:1) Myeloblast, 2) Promyclocyte, 3) Leucocytes. Haemocytoblast: It is the stem cell which gives rise to all myeloid cells. It isa relatively large cell about 10-14 diameter. Nucleus is large relatively undifferentiated and contains 1 or 2 nucleoli microns in vesicular. Cytoplasm is basophilic. therefore They are present in very small numbers in nucleus may be the bone marrow. 18  Haemocytoblast may differentiate into 1) Proerythroblast which develops into RBC or 2) Myeloblast which will develop into granulaocyte.. Myeloblast: About 0.3-5%ofbone marrow cells are myeloblasts. They have size ranging from 10-15im. They have large spherical nucleus, shows a delicate chromatin network and I or 2 nucleoli. cytoplasm is scanty and sonmewhat more basophilic than that ofhacmocytoblast. 2. Promyclocyte: They are largerthan myeloblast (upto 20um). Nucleus is oval with dense peripheral heterochromatin and an indistinct nucleolus. Cytoplasm is basophilic and contains acidophil granules with lysoz ymes. 3. Myelocyte: About 20-25% promyelocytes proliferate and differentiate into myelocytes. Myelocytes are 10 imindiameter. They have higher content of heterochromatin and in late myelocyte stage nucleus begn to assume a horse-shoe shape. Specific granules which have the size, shape and staining the characteristics that allow one to recognize that they are neutrophilic myelocytes or eosinophilic myelocytes. Acidophil granules decrease in number. 4. Metamyelocyte: About 20 to 25%ofbone marrow cells are Metamyelocytes. It is characterized by a curved nucleus witha deep indentationand oftenreferred as band cell. Chromatin is highly condensed and lobation may be seen. Cytoplasm shows characteristic granules. Development oflymphoid cells: The development oflymphocytes and monocytes occur in the bone marrow. Although the myeloid tissue has the potential for the process, the process of differentiation of these cells cannot be followed readily The appearance of definite characteristics such as nuclear lobation, cytoplasmic granulation and loss of cytoplasmic basophilia does not occur in lymphocytes and generally primitive nuclear shape of the stem cells. In post-natal mammals, most lymphocytes arise by proliferation ofpreexisting lymphocytes within the lymphoid tissues principally within the nodes and spleen. Only when a production is unable to supply lemand for lymphocytes, it is likely that there is any marked diffeèrentiation from the stem cells of bone marrow, plasma cells may arise 1 the lymphocytes. Thrombopoesis Platelets are produced in the bone marrow. Precursor cells of platelets are known as Megakaryocytes. They are giant cells (35- 150) m in diameter with granular cytoplasm and irregularly shaped lobulated nucleus. Cytoplasm is basophilic and nucleus contains coarse granules without nucleoli. Megakaryocytes fragments into cytoplasmic pieces without any nuclear material and these function as platelet. 1.3 Red Blood Cells Structure and Functions The RBCsare highly differentiated and specialized for transporting O, In lower vertebrates the erythrocytes are nucleated but in mammals (except Camel) the RBCs lose their nucleus, golgi apparatus, centrioles. endoplasmic recticulum and most ofmitochondria during maturation. The RBCs are spherical biconcave discs havinga diameter of8.6m. The mature erythrocytes are soft and flexible and can easily change its shape so that it can squeeze through the narrowest of capillaries. The membrane of the RBCs is selectively permeable. The bigger colloidal molecules and cations K, Na, etc. are not allowed to pass, whereas the anions Cl,-HC0,etc. are freely permeable of the 35%solids, 33% is haemoglobin. This is bound to the 2% meshwork, the meshwork consisting ofproteins and lipids, 19  O tne total lipids, phospholinids are 60%, 30% free cholesterol& 10% fats and cholesterol esters. Other creatinine, adenyl. pyrophosphates, diphosphoglycerates Ctc. are also nreea as urea, amino acids, is the chiet sait. r the salts in the corpuscle potassium phosphate Functions of Redblood cells: 1) RBCs carry O, and CO,. ACd base balance: The RBCshelps to maintain the pH of bloou. h e RBCs help to maintain the balance of ions in the blood. 4) The RBCs helps maintain the viscosity of to 5) igments like bilibrubin and blood. are derived from disintegrating RB biliverdina Abnormalities in form and structure of atm erythrocyte: mia:-Whenever the tissues become hypoxic (LessO,/anoxia because oftoo little 0, in the phere, such as high altitudes or because affailure ofO. reaching the tissues, there 1s more prouucion h e red cell countthen inereases to more than the normal count and this is called as polycythemia. Lwho luOn type of secondary polycythemia called as Physiological polycythemia occurs n the nauves live at altitudes of 14,000 to 17.000 feet. Oyythemia vera or erthyremia: In this condition the RBC count is 8 to 9 million and the haematoCTIt sesto 70% to 80%.Polycythemia vera isa tumorous Oer condition of the organs that produce KBS and Dlood cells. It causes excess production of the RBCs, WBCs and platelets. The total blood volume Ocasionally increases to twice the normal. The capillaries become increases firom 3 times the normal viscosity ofblood.Due to the plugged as the viscosity of the biood sluggish. increased viscosity the flow of blood is Total count: Normal RBC Count: The normal million/mm'. In infants the average count in the adult male is 5 is 4.5 count is 6 to 7 million million/mm' and in the adult female days after birth a large number of whereas in the foetus 7-8 million. In the first ten RBCs of the corpuscles are normally destroyed. The contents are in tendency to adhere to each other along their osmotic equillibrium with the plasma. The RBCs havea coins. concave surface and form rows or rouleaux like piled up Variation in Number of RBCs under various Diurnal daily variation: Variations physiological conditions: to about 5% occur in gradually increases towards evening, muscular exercise 24 hrs. The count is lowest during sleep and Altitude: At a higher altitude the RBC raises the count. count increases due to lack of O, Ahigher temperature raises the RBC count. Any condition increases the cell count.Adrenaline which lowers the O, tension increases the RBC count. in the blood Erythrocyte sedimentation rate or ESR:- When in circulation the RBCs remain is allowed to stand for uniformly suspended in the plasma. Ifblood with an sometime, the corpuscles settle down anticoagulant plasma remains as a clear supernatant fluid. This gradually at the bottom of the tube while the rate at which the process is called as sedimentation of erythrocytes settle down is called Sedimentation occurs in phases. There is a short as the erythrocyte sedimentation rateerythrocyte The there is maximum stage of aggregation of cells while in (ESR). velocity in the sedimentation of the second phase until packing of the RBCs is complete and RBCs.In the third phase the sedimentation decreases clear plasma is left.The depends upon the differences in the densities upper between the.RBCs and sedimentation of the RBCs plasma, degree of rouleax formation 20  which depends on the plas1ma protein content, and the resistance that plasma exerts on the RBC surface. RBCS carny a negative charge and hence any condition which increases the positive charge in plasma. accelerates ESR. The ESR increases due to factors such as, rise in O, rise in cholesterol, rise in fibrinogen and rise in globulin. The ESR decreases with rise in co,, albumin, nucleoprotein and lecithin. The ESR is measured either by the methods of wintrobe, westergren or cutter. Normal ESR values by Wintrobes methodare 0.0-65 mm/hr lowest in new borm, 0.0-2.00 mm/hr, in children it is from 3.0to 13.0 mm/hr, average 9.0 mm/hr, while in old age ESR increases. Types of Anemia Anemia mean a deficiency of RBCs.lt can be caused by i) rapid and excessive blood loss ii) slow production of RBCs ii) increased destructionof RBCs or haemolysis iv) resulting from defective function bone ot marrow which is called as aplastic anemia v) results because of deficiency of maturation factor or vi) any other nutritional deficiency vii) low production of Hb. 1) Blood loss anemia: After savior hemorrhage the body replaces the plasma within 1-3 days but not the RBCs. The RBCs concentration in the blood becomes low and there is a fall in haematocrit, the anemia which results is ofhe normochromic and normocytic type of anemia..If a second hemorrhage does not occur the RBCs concentration returns to normal within 3-4 weeks. In chronic blood loss, along with RBCs a considerable amount of iron is lost. The person frequently cannot absorb enough iron from the intestine to form Hb as rapidy as it is lost. Tissue anoxia stimulates the bone marrow to produce RBCs. The RBCs produced are small in size & with very little Hb inside them. The resulting anemia is ofthe les iron.hypochromic ,microcytic type of anemia. II) Hemolytic anemia: Many abnormalities ofRBCs make the cells very firagile. These abnormalities are hereditarily acquired the cells rupture easily as they go through the capillaries especially through the spleen therefore,even though the number of RBCs formed is completely normal the red cells life span is so short that the serious anemia results. a) Hereditary sperocytosis- In this type of anemia the cells are very small in size and they are spherical in shape.These cells cannot be compressed, while passing through minute capillaries these RBCs rupture easily as they are not flexible. This anemia is also called familial hemolytic anemia b) Sickle celled anemia:- This is commonly found in West African and American blacks Abnomalities ofchains of globin portion changes the physical characteristicsofthe Hb molecule. The RBCs tends to sickle at low oxygen concentration i.e. they take up a cresent shape instead of the normal biconcave disc like shape. Chemical studies have shown that the RBCs ofsicklecell anemia patients contain HbS rather than HbA. The Hb molecule has four polypeptide chains: Two o-141 amino acids and two B-146 amino acid chains. The a chains oftwo forms are identical. The Bchains differ in the two Hbs-HbA and Hbs Glutamic acid residue at point 6 in normal Hb is replaced by valine residue in HbS. When HbS is deoxygenated it becomes insoluble and forms bundles oftubular fibres, where as HbA remains soluble. The position ofthe residue in the å chain is critical point in the quatemary structure of Hb. Replacement of normal glutamic acid residue by valine creates a sticky hydrophobic contact point at position 6 ofa chains. This is on the outer change surface ofthe Hb molecule. These sticky spots causes deoxy-hacmoglolbin molecules to associate abnomally with each other to form long fibrous bundles aggregates. These are 21  responsible for stickling. The crystals which precipitate within the RBCs are sometimes ISHm in length teth Hb also makes the cell of the sickle. The precipitated Cell andgive it the appearance RBCs into blood capillaries without rupturing of them, Thie n e spikes ofthecrystal prevent entry called "sickle cell anemia. The patient often goes into a vicious cycle crisis" Th Osevere very to a severe decrease in nsion. The cycle continues and progresses rapidly leading withi few hours and RCBs within leads often to death. trait, tisaindividuals genetic disease have in which individual has inheriteda mutant Hb geneeonle from both suffering the parents. from this Thetrait sickle can L normal ndividuals have received the abnonnal gene from only one parent. People suffering from this trail can ve lives if they avoid vigorous exercise or other stresses on the circutatoy >y*. II Thalassemia: asmia was originally described in Italians, Greeks, and other peopleofthe Mediterranean region and therefore called as Mediterranean anemia, However now it is found to be wide spread througn Out ns is also called a Cooley's anemia or Mediteranean anemia. It is described as a heterogenous group or sorders in which there is a genetically determined reduction in the rate of synthesis of one or more ypes oT normal polypeptide chains. This results in a decrease in amount of Hb.In some forms of Thalassemia ne genetic mutation results in synthesis of structurally abnormal Hb, which is produced ar asiwa ceCn work amount of has shown that the gene causes a reduction in chain synthesis because of lack of normal The a mRNA for the affected chains. and chains of Hb are independently synthesized and are under separate genctic there are two main groups of thalssemia, there are two main Thalassemia-the one conro1. 1nus of a chains o affecting the synthesis - Thalassemia, the other affecting the he pThalassemia leads to reduction in the amountsynthesis of the Bchains-$ Thalassemia hypochromic anemia. It occurs in two forms- of HbA- in the red cells which results microcytic minor. BThalassemia major or Cooley's anima and BThalassemia Thalassemia major is a severe illness which often results in death transfusion are given. The new born infant with during childhood unless frequent blood The initial BThalassemia major is not anemic, the onset is insidious. symptoms are paler within first year of life the other There is symptoms are diarrhea and recurrent fever. enlargement of spleen,which causes abdominal swelling and pressure on changes in the skeletal system, secondary sexual characters surrounding organs, to deposition of iron in tissue results in organ underdeveloped be may cardiac dilation ,due disfunctioning. Aplastic Anemia: It is due to lack of functioning of the bone marrow. For from nuclear bomb blasts are example persons exposed to gamma ray radiations likely to have a complete destruction of lethal anemia. bone marrow which is followed by Similarly excessive exposure to X--rays for long time, poisoning from aromatic same destruction of bone marrow. chemicals or toxins cause It may also result due to cancer ofbone marrow, kidney diseases, substitution fibrous tissue. The resulting anemia is of normal marrow with of the normocytic type of anemia. Pernicious anemia: It results because of failure to absorb vitamin B12 from the gastrointestinal tract. This a basic abnormality a n atropic gastric mucosa that fails to secrete normal occurs because of Vitamin B 12 has been absorbed from the gastric secretions. gastro intestinal tract ,it is stored in then released slowly as required to the bone marrow and other tissues of large quantities in liver and body. 22  1.4 Haemoglobin Structure Haem molecule with iron atom B-chains chains Haem molecule with iron atom Fig. 2.8 Hemoglobin structure Haemoglobin is the red pigment of blood. tis chromo protein that helps in thetransportof O,. Haemo- globin consists of two parts 96% is globin, the remaining4% is prosthetic group. The globin is a oligo meric protein consisting offour polypeptide chains 2 á chains of 141 amino acid residues each and 2á chains of 146 amino acid residues each. The chains are folded to fom globular structure. The molecular weight of Hb is 64,5000. X-rays analysis has revealed that the molecule is roughly spherical with a diameter ofabout 5.Snm. There is one haem group bound to each chain. The haem are about 2.5nm apart from each other and bent at different angles. Each haem is partially buried in a pocket, linked with hydrophobicR-groups. It is bound to its polypeptide chain through a co-ordination bond ofthe iron atom to R-group ofa histidine residue. Haem is a metallo porphyrin compound. It consists of Protoporphyrin and Fe. Porphyrins are tetrapyrrole compound i.e. it consists of 4 pyrrole groups joined together. The porphyrin molecule can combine with metals forming metalloporphyrin coumpounds. The haem group consists ofa complex organic ring like structure protoporphyrin to which Fe is bound in a ferrous state. The Fe atom has 6 co-ordination bonds. One is bound to the nitrogen atom of a histidine residue & the second is open and serves as a binding site for an O, molecules. Properties of haemoglobin : The most important property of haemoglobin is its capacity to combine very easily with O, AtNTP 100ml cfblood can combine with 20ml ofO, whereas the same amount ofwater can combine with only1/ 3 ml of O, under the same conditions. Haemoglobin can combine with other gasses like CO, NO, H,S ete. They formmore stable compounds with Hb than O, Haemoglobin can be easily crystalized. Most bloods including human blood form rhombic prisms or needles. Haemoglobin can be crystallized by glacial acetic acid. Hbdiffers in diferent speciesinimmunologically and this specificity lies in the globin part and not in the haem part. The haemoglobin of different species also shows different affinity for 0, Formation of Hb:- Haemoglobin is synthesized inside the red cells in the bone marrow. Ano of factors are necessary for the synthesis ofHb. Proteins ofhigh biological value are necessary for the synthesis of globin part of Hb. Certain amino acids like histidine, leucine, phenylalanine etc. Possess a stimulating action on Hb formation. Adiet containing kidney, spleen, heart and certain fruits is very useful. 23  Metals like O iron,l copper, manganese and cobalt are essential for tlb synthesis. The ratio of Cu: Fe in our daily diet should be 1:100. Daily intake of 12 mg ofFe is sufficient. Cobalt is a constituent of Vitam B which acts as a catalytic agent. Endorerines:- Thyroxine plays VItamins:- Vitamin Cand areimportant B,,an part in Hb most important andsyntnesi in addition folic nofHb. acid, riboflavin, nicotinic acid, panthenic acid & pyridoxine also play an important part in the rorma ns Porphyrin I and Il are used for Hb formation. Both are found in naturc Functions of Hb. It is essential for the transport of, O, and CO, balance of blood. s One of the most important buffers of blood and helps to maintain the acid-base Various pigments of bile, stool, urine are formed from haemoglobin. Degradation of Hb:- Ater the fragmentation of RBCs the tlb is released & by degradation the porpythr1n ring opcis agnt chain. This is called as verdohaemoglobin or choleglobin. The verdohaemoglobin is ine DO sto is broken down into amino acids. The Fe present hacm is SLOrca in m protein the body as ferritin oand The and haem. protein This is used in the formation ofnew haemoglobin. haemosiderin, 1ne n a e m molecule is converted into a yellow piement bilirubin which is then oxidized into a gree P t DIliverdin, are according to some biliverdin is formed first andby reduction biliverdin changes top bilirubin. Bilirubin & Biliverdin combine DIirubin & withx, globulin of plasma & enter the liver. In the nver c biliverdin separate fromx, globulin & combine with uridine diphosphate glucouronate to proauce monobilirubin glucuronide& dibilirubin Varieties of Hb: In man gluccuronide. roetal probably there are at least 2 varieties of Hb he Hb(Hbt) and the adult heamoglobin Hb(A) Foetal haemoglobin has greater affinity O, a for and can also more readily give up CO, than Hb(A). At low O, pressure foetal haemoglobin can take up larger volume of O, than adult as Adult tlb is haemoglobin. Foetal Hb is 70% saturated at 20mm ofO, pressure where only 20% saturated. It is believed that haemoglobin remains absorbed (remains on surface) to the lipid material at the stroma and envelope of red cells. I certain lower invertebrates the haemoglobin remains free in the plasma. Abnormalities in HB: a) Sickle celled anemia:-This is commonly found in West African and American blacks. of chains of globin portion changes the physical characteristics of the Hb molecule. The Abnormalities RBCs tends to sickle at low oxygen concentration i.e. they take up a cresent shape instead of the normal biconcave disc like shape. Chemical studies have shown that the RBCs of sickle cell anemia The Hb molecule has four patients contain HbS rather than HbA. polypeptide chains: Two á- 141 amino acids and two â -146 amino acid chains.The á chains of two forms are identical. The â chains differ in the two Hbs-HbA and Hbs Glutamic acid residue at point 6 in normal Hb is replaced by valine residue in HbS. When HbS is deoxygenated it becomes insoluble and forms bundles of tubular fibres, where as HbA remains soluble. The position of the residue in the â chain is critical point in the quatermary structure of Hb. Replacement of normal glutamic acid residue by valine creates a sticky chains. This is on the outer change surface of Hb molecule.hydrophobic contact point at position 6 of â the These sticky spots causes deoxy-haemoglobin molecules to associate abnormally with each other to form long fibrous bundles aggregates. These are responsible for stickling. The crystals which precipitate within the RCBs are sometimes 15Hm in They elongate the cell and give it the appearance of the sickle. The length. membrane fragile. The spikes of the crystal prevent entry of RCBs into blood precipitated Hb also makes the cell capillaries without rupturing 24  them. This leads to severe anemia. The patient very often goes into a vicious cycle called "sickle cell crisis". The low O, tension. The cycle continues and progresses rapidly leading to a severe decrease in RCBs within few hours and leads often to death. Itis a genetic discase in which individual has inherited a mutant Hb gene from both the parents. Thesickle trait, individuals have received the abnormal gene from only onc parent. People suffering from this trait can live normal lives ifthey avoid vigorous exercise or other stresses on the circulatory system. Thalassemia- Thalassemia was originally described in Italians, Greeks, and other people ofthe Mediterranean region and therefore called as Mediterranean anemia. However now it is found to be wide spread through out. This is also called a Cooley's anemia or Mediterranean anemia. It is described as a heterogenous group of disorders in which there is a genetically determined reduction in the rate of synthesis of one or more types ofnormal polypeptide chains. This results in a decrease in amount ofHb.In some forms of Thalassemia the genetic mutation results in synthesis of structurally abnormal Hb, which is produced at a slower rate recent work has shown that the gene causes a reduction in chain synthesis because of lack of normal amount ofmRNA for the affected chains. The á, â and chains of Hb are independently synthesized and are under separate genetic control. T hus there are two main groups ofthalssemia, there are two main Thalassemia-the one affecting the synthesis ofá chains-á Thalassemia, the other affecting the synthesis ofthe â chains-å Thalassemia The â Thalassemia leads to reduction in the amountof HbA-in the red cells which results microcytic hypochromic anemia. It occurs in two forms á Thalassemia major or Cooley's anima and â Thalassemia minor. A Thalassemia major is a severe illness which often results in death during childhood unless frequent blood transfusion are given. The new born infant with â Thalassemia major is not anemic, the onset is insidious. The initial symptoms are paler within first year oflife the other symptoms are diarrhea and recurrent fever. There is enlargenment of spleen,which causes abdominal swelling and pressure on surrounding organs, changes in the skeletal system, secondary sexual characters underdeveloped may be cardiac dilation ,due to deposition of iron in tissue results in organ disfunctioning. 1.5 WBCs- LEUCOCYTES WBCs are important variety ofcells in the blood. These cells differ from RBC with large size and large nucleus, no haemoglobin, amoeboid, there are several varieties and they are defensive in function. Different types of WBCs: On the basis of presence of specific granules in the cytoplasm the WBCs are classified into 2 groups namely, granulocytes and agranulocytes. The WBCs can also be distinguished into polymorphonuclear and mononuclear cells based on their nuclear morphology. In addition they can be classified as myeloid and lymphoid cells depending on their origin. Neutrophils Eosinophils Basophils Lymphocytes Monocytes Fig. 1.5 Types of WBCs 25  Granulocytes and they originate from the bone citic granules in the cytoplasm, nucleus iregular is marrow. Tha marrow. They are distinguished into neutrophils, eosinophils and basophils depending on the staining affinity oftheir yTinity of their o their granules. The The increase increase in granulocytes in mas granulocytosis while m blood is known as ranulocytosis while a a decrease deTCase in granulocytes bioou t n e number is called granulocytopenia. Complete disappearance franulocytes blood isis called of granulocytes in in blood called agranulocytosis. 1. Neutrophils diame mocboid and constitute 60-70%ofcirculating leucocytes. They are about i2 miCrOns in dmeter, With a nucleus having 2 to5 lobes. Old cells have more nuclear lobes than the younger cells. In human females theneutro phils have a small drumstick shapednuclear appendage consistingofchromatin tacned to one of the nuclear lobe by a fine chromatin strand.It is seen ohout 3% of in about 3% of the cells and the cells S tne sex chromatin. The abundant cytoplasm is filled with granules of about 0.3 to 0.8 microns. CSe granules stain with neutral dyes or with a mixture of an acidic and basic dye (e.g. eosin and methylene blue). 2. Eosinophils:- EOsinophils are about of 1-4% ofthe total leucocytes and have diameter of about 9 microns. Nucleus is Dilobed and appears like a spectacle. Cytoplasm contains lysosomal in size that take up eosin stain and therefore appear granules of about 0.5- 1.5 microns pink. Eosinophils are less amoeboid as compared to neutrophils. 3. Basophils: Basophils are about 0.1%ofthe total leucocytes and have size is large, irregular and twisted. They have of about 10 to 12 microns. Their nucleus Granules contain histamine and large and irregular granules which appear violet on staining. heparin. Agranulocytes Agranulocytes have one-lobed nucleus and do not have cytoplasm ic in to two types namely, lymphocytes and monocytes. granules. They can be distinguished i) Lymphocytes:- They constitute about 20-25% of total WBC's count.They are of large and small lymphocytes. The small lymphocyte is about 8 micron two types namely, in diameter and has a nucleus occupies most cellular area with a thin rim of that to 12 microns in diameter and bluish have a round or bean cytoplasm. The large lymphocyte measure about 10 takes up a light blue color. shaped nucleus. The cytoplasm is basophilic and i) Monocytes:- They constitute about 3-5% of Nucleus is oval, horse-shoe shaped or total WBCs count and have diameter of 16 to 20 microns. kidney shaped and is generally eccentrically placed. is basophilic with bluish grey colorand reticulated. Cytoplasm Functions of WBCs Phagocytosis:-Neutrophils called and monocytes engulf foreign particles and bacteria and digest them, phagocytosis. When bacteria invade the body the leucocytes pass out of the blood a process surround the site of infection and phagocytose the vessel and like enzyme with which they invading pathogens. Neutrophils manufactured a digest the bacteria and the dead tissue. This trypsin dead tissue in the inflamed area partially liquefied and is called pus monocytes act like scavengers removing this dead and lymphocytes have slight phagocytic activity. matter.Eosinophils Antibody formation:-Lymphocytes manufacture antibodies which mechanism. play an important role in the defense 26 Formation of fibroblasts:-Lymphocytes are converted into fibroblasts in an area of inflammation,which protect the surounding normal tissue and prevent spread ofinfection. called Manulacture oftrephines:-Leucocytes manufacture certain substance from plasma protein trephines,which influences growth and repairoftissues. Secretion of heparin : Basophils produce heparin which preventsintravascularcloting which Is Iniammatory function:-The granulocytes especially the eosinophils are very rich in histamine, an important mediatorofinflammation.Histamines increase the capillary permcability, which results in increased migration of WBCs at the site of infection and kill the pathogens. lotal count - The WBCs count is 5000 to 10,000 per mm. The ratio between WBC and RBC is 700. Ifthe number is increased about 11,000 the condition is called leucocytosis, while a decrease below 5000 is called leucophilia. Variation in number: The WBC count change due to various factors. It is lowest in the morning and highest in the evening 20000 Muscular exercise and emotional stress causes increase in numbers. New born infants have per mm of which 50% are lymphocytes. Pregnancy and labor increase the amount of WBCs. Infection, allergy conditions, skin disease and surgicaloperations cause increase in WBCs. Starvation,administration ofdrugs like benzene, sulpha drugs, bone marrow disease ionizing radiation decreases WBC count Starvation and administration of certain chemicals like benzene, sulphonic acid etc. produces ieucopenia. Leukemias: Leukemiais a disease of unknown etiology characterized by an uncontrolled abnormal and widespread proliteration of the leucocytes which infiltrate the bone marrow and other body tissues. The uncontrolled proliferation of WBCs is usually accompanied by the appearance in the peripheral blood of immature WBCs which are morphologically abnormal.The exact cause is unknown but a possibility ofhereditary predisposition toward the disease exists. There is also an increased incidence of leukemia in radiologists and in people having undergone extensive x-ray therapy. A viral etiology is also suggestive.In all forms of leukemia there is a marked increase in the number of WBCs. But increase of WBCs is not always indicative of leukemia. Temporary counts as high as 100,000 are seen in many infections. Leukemia can be classified based on, 1) Courseofthedisease into acute and chronic, and 2) Typeofthe leucocyte affected. Myelocytic leukemia:- It is seen usually between the ages of 25 to 45. It is characterized by hyperplasia ofthe myeloid tissue. Myelocytesare large cells about double the size ofthegranulocytes. Myeloid cells are found in abundance in the spleen, lymph nodes, liver, kidney and other organs. There is an increase in in early stage thenumberofmyelocytesinthe blood.Largeamountofleucocytes ofdevelopment are seen in the terminal stages or in the acute form of leukemia.In the bone marrow, erythroblast tissue is largely replaced by leucoblastic tissue. Spleen, liver lymph node may show enlargement. The patient suffers from increasing weakness, anaemia, hemorrhages in the skin, eyes, mucus membrane, headache. pain in bones especially the sternum. Lymphoeytic leukemia: It occurs in age groups 45 to 60 years. In this formofleukemia. lymphoid cells increase in the blood while the myeloid cells are unaffected. Lymphocytes may increaseas much as 90 to 95%ofthe total WBC count. The total WBC count is rather lower than in the myelocytic fornm. These lymphocytes contain less cytoplasm than the nonal smalllymphocyte, so that they appear as nuclei only. Anemia is much less marked than in myelocytic leukemia. In the lymphocytic leukemia there is a drastic decrease orcompletedisappearanceoftheplatelets. The lymph nodes cverywhere are enlarged. Chronic granulocytic leukemia:lt is a disease predominantin middle age between 30 to 60 years. Symptorms progress slowly such asanemia, spleen enlargement, raised BMR, hemorrhage, fatigue. weakness, weight loss, skin lesions, bone and joint pain. WBCs are exclusively high. Philadelphia chromosome is present in almost all cases. The average duration of life from onset in 3 to 4 years or may be 10 yrs. 27  1.6 Thrombocytes nese are non-nucleated biconvex discs having various sizes covered by a unit membrane. Ihe average I n ordinary blood films the platelets are not scen separately but in clumps.In blood The average number of platelets present per cuihiads such EDTA the platelets appear separate. as Of blood is about 2,50,000to 4,50,000. Thrombocytes show fairly rapid diurnal changes Eal conditions which alter the leucocyte count eucocyte count alc nrombocytopenia. Roughlythose physiological also alter the platelet count. Under a light microscope 2 componenets of platelets are seen.The peripheral lightly called platelets:- L y area called hyalomere (hvalos=elass: mere-nart) and the deeply stained central position called rmotomere or granulomere. Under an electron microscope the hyalomere 1S Seen uDules and microfilaments. Microfilaments contain thrombosthen y s n or the muscles and which is responsible for change in which can contact like actin of shape of platelets. Chromatomere conlains and numerous substances. 4pna granules: these granules are oval or round with a diameter of 0.2u and enclosed in a ney considered important in clotting or in phagocytic activity memorane. COnaning granules, of platelet.Mitochondria,5erotonn Gycogen granules,Ribosomes,System of tubules and vesicles Chemistry: platelets possess protein and considerable amount Properties: 1) Sticking to water-wettable surface of phospholipids. or rough broken surfaces like membrane. 2) Easy injJured enaouC clumping 3) Easy disintegration and liberation of thrombokinase. Functions Initiate blood clotting-when blood is shed the platelets disintegrate and liberate initiates conversion of prothombin into thrombin. thromboplastin which Repair capillary endothelium-when and thus in circulation, platelets adhere to the damaged endothelial bring about a speedy repair. It is known that capillary walls being very delicate are lining damaged and unless these are quickly mended, the vessels will easily occurs. break at these spots and capillary bleeding Haemostatic mechanism-Due todual function ruptured blood vessels is plugged off. of coagulation and agglutination, blood flow through a Hasten clot retraction-speed ofclot retraction is directly proportional to the number clot retraction is dependent upon release of thrombosthenin. of platelets and Vasoconstrictor effect. When platelets disintegrate, histamine, 5-HT and other similar substances are released which have vasoconstrictor effect which narrows the diameter Blood Clotting blood injured vessels. When the blood is shed it loses its fluidity in few minutes and sets into a semisolid jelly. in a test tube it will set into jelly. On further Ifblood is collected keeping the clot retracts to a smaller volume and presses out a clean straw colored fluid called the serum. The serum does not clot any more. When a section of this is examined under the clot microscope it is found to be composed of a tangled mesh of among which are entrapped erythrocytes, leucocytes and many very delicate, fibrils fibrils are composed of fibrin, an insoluble fYom of fragmented platelets. The filaments or The serum does not clot since it does not contain fibrinogen produced during the clotting process. fibrinogen. Plasma separated from the blood cell by centrifuging in a similar way will show clotting and expresse out the clear serum. The clot is white does not contain RBCs. The clotting process is since it essentially therefore a phenomenon of the plasma. Lymph also clots through somewhat more slowly and less fimly than does blood or plasma. The coagulation of is enormous physiological importance. When bleeding occurs, the shed blood phenomenon of coagulates 28  and blood vessels become plugged off. The reaction ofthe clot further compresses the blood vessel and the bleeding is stopped. Mechanism of clotting When blood is shed the platelets disintegrates and liberates thromboplastin. Certain amount of thromboplastin is also derived from the injured tissue surrounding the wound. Thromboplastin converts prothrombin into thrombin with the help ofCattions.Thrombin interacts with fibrinogen forming fibrin clot. Blood does not clot in the living body because there is not sufficient free thromboplastin to convert the inactive prothrombin into the active thrombin. The presence ofnormal antithrombin in the plasma neutral1zes the action of any thrombin which might be present. There are about 13 factors concerned with blood clotting Clotting factors Fibrinogen Prothrombin Tissue thromboplastin Calcium Proaccelerin/ labile factor Accelerin Proconvertin Antihaemophilic factor (A) Christmas factor (B) Stuart factor Antihaemophilic factor C/Plasma thromboplastin Hageman factor Fibrin stabilizing factor. The intrinsic extrinsic theory of blood coagulation suggest that prothrombin can be activated to thrombin by one ofthe 2 substances which are termed as (a) extrinsic thromboplastin (b)intrinsic thromboplastin. Extrinsic thromboplastin is produced in tissue. It is acted upon by certain factors present in blood. The tissue extract requires to be activated by factor V, VII, X and calcium to form extrinsic thromboplastin. Intrinsic thromboplastin is produced in blood. These factorsare V, VII, IX, X, XI and XII and free Cations and platelet factor. It is thought that factor XII,when coming into contact to a foreign surface is activated to form activated factor XII. This then reacts with factor XI to form an activation product. The activation product reacts with factors IX, VII, X, V, platelet factor in the presence of Cat+ ion to form intrinsic thrombin which in tum convert fibrinogen to fibrin. Failure of clotting Mechanism Failure ofclotting may be due to:- Lack offibinogen (fibrinogenopenia) Lack of factor VIll (hemophilia) Decrease ofProthrombin (hypoprothrombinemia) Deficiency of factors V, VIl and IX Fibrinogenopenia: This is very rare disease. It is a congenital defect in which hemorrhagic tendencies are seen. Hemophilia: It is an inherited sex linked disease. The genetic characteristic is carried by the females who transmit it to their male offisprings. The defect is transmitted to grandsons through carrier daughter. 29  In this disease, the coagulation time is greatly prolonged. Due toan increase in coagulation time (1-12 known as blceders. are popularly g e may follow a wound. The subjects This it for hemophilia is probably a deficiency ofa plasma thromboplastin.Anti. plasma thromh ponsible called factor VIll or n 1actor is associated with the globulin factor and has been hemophilic globin. blood restores the normal added to hemophilic clotting time Or hormal platelet free plasma vitamin the k is required for svnthesis of prothrombin by liver. In the absence ofthis nla Vitamin proIonged dprothrombin concentration is reduced and the coagulation time is correspondingly and severe so hemorrhage may occur. Pseudohemophilia: Congenital deficiency of any of the factors concened in the generation of thromo0pa hagie condition simulating hemophilia. Such deficiencies have been described in the cases of factor V, VIl and IX. Purpura: m tnis disease there is diminution in number of platelets. Haemorhage occurs beneath the skin and mucous membrane. The appearance of lesions varies with the type of purpura, the duration or iestol, ad acuteness of the onset of the condition. 1.7 Blood Volume Definition: The term blood volume means total amount ofblood in circulation as well as in the blood reservoirs of the body. It is expressed in 2 ways. In relation to body weight: It is 78 to 98 ml/kg of body weight or about 1/11th of the body weight or 9 % of the body weight. Plasma is about 50 ml/kg or /20th or 5 % In relation to body surface: It is 2.5 to4 of body weight. litres i.e. average 3.3 litres/m has 5-6 litres of of body. blood in circulation. Blood volume is more in males than females except Malesweighing 70 kg Regulation of blood volume during pregnancy. The total blood volume does not remain constant and varies widely under different The variation is mostly in the cells than physiological conditions. plasma which is fairly constant because of, Balance between water intake and output. Fluid exchange between tissue fluid and blood occurs due to counterbalance osmotic pressure (filtration pressure) which help maintain constant volume. pressure and blood Tissue spaces act as reservoirs and any increase in blood volume is immediately followed fluid from blood to tissue spaces. by passage of Vitamin C controls permeability of capillaries. Endocrine factors like adrenal cortical hormones control salt water. The parathyroid gland affects Ca"" metabolism balance, kidney function and excretion of which in turn controls Antidiuretic factor from the posterior pituitary controls excretion capillary permeability. Thirst is a phenomenon due to which blood volume is of water through kidneys. kept constant. Variation under physiological conditions: Age- In infants blood volume is larger in proportion to body Sex-Increase in volume in males is due to greater number weight. of RBC. Plasma volume is nearly the same. 30  Pregnancy-Increase in volumeis due to both plasma and calls. Muscular exercise -It raises blood volume due to contraction ofsplcen. Posture- Blood volume reduces by about 15% in standing posture because much ofthe plasina pass into the tissues. Blood Pressure - Increase in blood pressure decreases blood volume by pressing out fluid into tussue spaces. Lower blood pressure draws in more fluid. Altitude- At higher altitude blood volume raises due to anoxia (lack of Oxygen) in volume is due to increase in number ofRBCs. Anoxia - Anoxia duce to any cause increases the blood volume. Adrenaline injection -Adrenaline raises the blood volume due to contraction ofspleen. Changes in blood volume in disease conditions: 1. Haemorthage 2. Anaemia 3. Loss ofplas1ma alone.4. Loss ofwater (anhydracmia) 5. Acute exposure to cold.6. Posture. Increase in blood volume due to physiological conditions:- 1. High temperature 2. Muscular action 3. Emotional excitement 4. Pregnancy 5. Congestiveheart failure. 6. Administration of mineral corticoids. Haemorrhage Haemorrhage may be defined as a sudden loss ofblood through a blood vessel which may be broken during an injury or a disease. It is a loss of both plasma and cells. The blood may escape from the body following an accident in which a vein or artery may be injured. Here the haemorrhage is external. On the other hand in internal haemorrhage, blood comes out from an internal blood vessel into the surrounding tissues like the cavity of the viscera, digestive canal, colon heart, lungs, brain etc. however effects are generally the same. The effects of hacmorrhage depend on its severity and duration. Ifa small amount of blood is lost there is a temporary fall in the B.P. as a result ofreduction in the blood volume of circulating fluid and the rate of heart beat increases. Ifthe haemorhage is severe the recovery process is slower and the blood volume is rapidly made up from the tissue fluids which enter the blood as a result offall in capillary pressure or filtration pressure (blood pressure) at the arteriolar end ofthe capillary. Ifthe quantity of blood lost is large and sudden, the individual suffers severely from lack ofO,. The respiration at first becomes deeper and more rapid so as to gain more O, The respiration becomes prolonged. Due to fall in B.P heart rate increases so as to compensate. Unless a large blood vessel is injured haemorrhage is seldom immediately fatal, but may lead to progressive circulatory failure. The 1 prerequisite is to stop the bleeding immediately and this is accomplishedthrough cloting ofblood, contraction ofthe walls of the cut vessels and sticking together of the inner coat of the vessel may be repaired. In order to maintain the blood pressure in the vital organs like brain, heart lungs the volume of circulating blood in organs like skin, muscles, intestine whose functions are not immediately essential to life is reduced by narrowing at the blood vessels in those organs. Adequate pressure towards heart and brain is obtained in this way Spleen which is a reservoir of blood contracts and discharges blood into circulation. The blood volume is also augmented by the passage of fluid from the tissue spaces into the capillaries. The withdrawal of fluid from tissue spaces causes the patient to suffer from thirst and administration offluids alleviates the condition. ***** 31