1. BLOOD Part 1.pdf

INTRODUCTION TO BLOOD DR LWIINDI  BLOOD Composition And Functions Blood is a fluid, which circulates in the vascular channels of human body due to the pumping action of heart. It is red in color and consists of a liquid portion called plasma in which various types o...

INTRODUCTION TO BLOOD DR LWIINDI  BLOOD Composition And Functions Blood is a fluid, which circulates in the vascular channels of human body due to the pumping action of heart. It is red in color and consists of a liquid portion called plasma in which various types of cells are present. The cells which are suspended in the plasma are of three different types  1.Erythrocytes or red blood cells The color of these cells is red due to presence of an iron containing pigment known as hemoglobin. 2.Leucocytes or white blood cells They are of different types (5) 3.Thrombocytes or Plateletes These cells help in the coagulation of blood  1.Erythrocytes or red blood cells The color of these cells is red due to presence of an iron containing pigment known as hemoglobin. 2.Leucocytes or white blood cells They are of different types (5) 3.Thrombocytes or Plateletes These cells help in the coagulation of blood  GENERAL FUNCTIONS OF BLOOD Blood performs various important functions, which could be summarized as follows; 1.Respiratory Tissues and organs require a constant supply of oxygen to maintain their activity and simultaneously they form carbon dioxide and other waste products. Blood and particularly the red blood cells are responsible for transport of oxygen from the lungs to the tissues. This is due to the presence of hemoglobin, which combines with oxygen to form oxy-hemoglobin. Carbon dioxide from tissues is taken up by the blood and released in the lungs.  2.EXCRETORY As a result of metabolic activity there is a constant production of waste products. Blood transports them to the kidneys, lungs, skin and gastrointestinal tract for excretion. 3. NUTRITIVE Food is digested into simpler end products in the digestive tract. These substances are absorbed from the intestine and transported to all parts of the body by the blood  4.DEFENSIVE Blood protects the body against infections. This is achieved in different ways. Leucocytes have the ability to engulf and destroy invading organisms and the property of white blood cells is termed as phagocytosis. These cells form the defense force of the body and during infection their count increases. This virtue forms the basis of immunization against diseases.  5.COAGULATION It is a mechanism by which various factors present in the blood form a clot and thus prevent blood loss 6.ACID BASE EQUILIBRIUM Cell and enzyme activity require maintenance of a constant acid base equilibrium. Blood contains buffers which maintain the pH constant.  7.BODY TEMPERATURE The water content of the blood is 90%. It has a high specific heat and high latent heat of evaporation, which help blood to maintain the body temperature. 8.TRANSPORT OF SUBSTANCES Blood is in rapid circulation and as such substances like hormones, vitamins and drugs are easily transported all over the body. 9. PROTEIN RESERVE Plasma proteins to a certain extent act as protein reserve and are used in extreme protein deficiency to form cell proteins. Section 1 Components and Characteristic Water: 93-95% Plasma: 50-60% Solutes: 5-7% Proteins: Nutrients Whole Products Electrolytes: blood Others: urea, gases. WBC, Platelet: 1% RBC: 40-50% (male) 37-48% (female)  Blood Components Water: – 93~95% (plasma); 65~68% (RBC); 81~86% (whole blood). – Solvent, humoral balance, osmotic pressure. Electrolytes: – Na+, K+, Mg2+, Cl-, HCO3-, etc. Cell shape, pH. Proteins: – Albumin: 40-48g/L. Colloidal osmotic pressure; carrier; buffer pH. – Globulin: 15-30g/L. Immune reaction: antibody; carrier. – Fibrinogen: 2-4g/L. Blood coagulation.  – Hemoglobin (Hb): 120-160g/L (male), 110-150g/L (female) Function: carry gases. Others: – carbohydrates, lipids, amino acid, pigments, hormones, gas (O2, CO2), and others like urea, uric acid.  Physical and chemical properties Blood pH: – Normal interval: 7.35~7.45. Regulated by lung and kidney. Viscosity: – Friction of molecules and cells in blood. – Relative viscosity: Whole blood: 4~5 times to water (RBC). Plasma: 1.6~2.4 times to water (Proteins). Anemia or body fluid loss.  Osmotic pressure – Definition: An ability of a liquid to attract and retain water. It drives osmosis. 300mmol/L – Composition and roles: Crystal osmotic pressure: 298.7 mmol/L. – Maintain shape and size of cells. Colloid osmotic pressure: 1.3 mmol/L. – Retain blood volume – Decide distribution of water between blood and interstitial fluid.  PLASMA It is the fluid part of the blood in which formed elements are suspended. The relative quantity of plasma and cells is in the ratio of 55:45. If blood mixed with an anticoagulant is taken in graduated tube and centrifuged for about half an hour, the cells being heavier, settle at the bottom of the tube and constitute about 45% of the blood volume. This is known as packed cell volume (PCV)  5 liter in adult 45% is packed cells volume (PCV) 55% is plasma volume Dr Sitelbanat 16  Hematocrit (packed red cell volume) - definition: fraction of the blood composed of RBC - functional significance - methods of determination: centrifuging blood in a calibrated ‘hematocrit tube’ - values ~ 35% – 45%; ~ up to 10% in severe anemia ~ up to 65% in polycytemia - corrected Ht = 0,96 Ht (3-4% from the measured Ht is represented by entrapped plasma) - venous vs. arterial hematocrit … - relation hematocrit – blood viscosity…  COMPOSITION Plasma contains 91-92% water and 8-9% of solid substances, which are both organic and inorganic in nature. In organic constituents are less than 1% and are mostly chlorides, carbonates and phosphates of sodium, potassium and calcium. Small amounts of iron, copper and iodide are also present. Sodium bicarbonate present in the plasma helps in the maintenance of blood pH during carbon dioxide transport.  Organic substances form the major bulk of solids present in plasma and they are; Plasma proteins (6.5-8 gms %) Glucose (80-120mg%) Cholesterol and lipids (150-250mg%) Non-protein nitrogenous substances like urea, uric acid, creatine and creatinine Hormones, enzymes and blood pigments.  PLASMA PROTEINS They are specific proteins present in plasma and are of three different types; 1. Albumin It forms the major bulk of plasma proteins and has a molecular weight of 60,000. Albumin content of plasma is 4-4.5gm%.  2.Globulin It constitutes about 2.5 gm of plasma proteins and has a relatively higher molecular weight of 1,30,000. Various types of globulins have been identified like alpha, beta and gamma globulin. The latter plays an important role in antibody formation. Prothrombin which helps in the coagulation is beta globulin and its plasma content is 0.1 gm%  3.Fibrinogen Blood coagulation requires this protein. The chemical nature of clot is fibrin, which is formed from fibrinogen. About 0.25 gm% of fibrinogen is present in blood. Fibrinogen and prothrombin are utilized in the clotting and plasma devoid of these two proteins is called serum. It only contains albumin and globulin. There are various methods by which plasma proteins can be isolated, like half or full saturation with ammonium sulphate or electrophoresis.  FUNCTIONS 1. Colloidal osmotic pressure It is 25mmHg. Albumin being the major plasma protein primarily influences the colloidal osmotic pressure. This is responsible for preventing fluid exit from the capillaries. 2. Antibody formation. Antibodies form an essential defense mechanism. This virtue is attributed to the gamma globulin  3. Coagulation Fibrinogen and prothrombin are involved in the clotting of blood. Various other clotting factors also belong to globulin. 4. Transport media Certain substances bind themselves with albumin, alpha and beta globulins and are transported. The transport of hormones, metals, drugs, dyes are examples of this function.  5. Erythrocyte sedimentation rate( ESR) is influenced by the fibrinogen content of plasma. 6. Viscosity Fibrinogen and globulins, due to their high molecular weight and irregular shape contribute to blood viscosity. 7. Buffer mechanism, plasma proteins act as buffers and maintain acid base balance. 8. Protein reserve. During emergency, cells of the reticuloendothelial system break them into amino acid. Subsequently these are used for the synthesis of cell protein  The erythrocyte sedimentation rate (ESR) - commonly used, inexpensive, but non- specific laboratory test (Westergren, 1921) - measures the speed of sedimentation of RBC/RBC aggregates in plasma over a period of 1 hour in a vertical column of anticoagulated blood under the influence of gravity - sialic acid-rich glycoproteins on cell surface membranes contribute to creating a negative charge on the cells’ surface 􀃆 cellular repel … Erythrocyte sedimentation rate (ESR) cont….. - a raised ESR is associated with marked rouleaux formation of RBCs - mainly depends on plasma concentration of large proteins (fibrinogen, Ig) - ESR raised in systemic inflammatory & neoplastic diseases; useful in chronic diseases, for monitoring disease activity/response to therapy  The basic factors influencing the ESR - increased ESR with elevated fibrinogen (e.g., pregnancy, collagen vascular diseases, malignancy). decreased albumin conc. anemia (hematocrit is reduced, red blood cell aggregates fall faster); macrocytic red cells also settle more rapidly. a decreased ESR is associated with: hypofibrinogenemia, hypergammaglobulinemia associated with dysproteinemia, and hyperviscosity blood diseases in which RBC have an irregular or smaller shape that causes slower settling; increased albumin concentration – an abnormal value remains a nonspecific finding