Blood Physiology PDF

PIO 201 LECTURER: O. E KAYODE Blood is a connective tissue in fluid form. It is known as the: Ø Fluid of life: Because it carries oxygen from lungs to all parts of the body and carbon dioxide from all parts of the body to the lungs Ø Fluid of growth: It carries nutritive su...

PIO 201 LECTURER: O. E KAYODE Blood is a connective tissue in fluid form. It is known as the: Ø Fluid of life: Because it carries oxygen from lungs to all parts of the body and carbon dioxide from all parts of the body to the lungs Ø Fluid of growth: It carries nutritive substances from the digestive system and hormones from endocrine gland to all the body tissues Ø Fluid of health: It protects the body against the diseases and remove waste products and unwanted substances through excretory organs like kidneys. 1. Color: Arterial blood is red because it contains more oxygen and venous blood is purple red because of more carbon dioxide 2. Volume: Average blood volume in a normal adult is 5L. In a newborn baby, the volume is 450 ml. It Increases during growth and reaches 5 L at puberty stage. It is about 8% of the body weight in a normal 70 kg young healthy adult. 3. pH: Blood is slightly alkaline and its pH in normal conditions is 7.4. 4.Specific gravity: Density ratio of substance todensity of reference substance. Specific gravity of total blood : 1.05 to 1.06g/L 5. Viscosity: The Blood is five times more viscous than water; due to red blood cells and plasma proteins Blood is made up of two components: Ø Solid components: Blood cells/corpuscles ( RBC,WBC, Platelets) Ø Liquid components: Plasma Ø NB: Blood cells are produced by long bone marrow in adults Three types of cells are present in the blood: 1. Red blood cells or Erythrocytes 2. White blood cells or Leukocytes 3. Platelets or Thrombocytes. v Red blood cells (RBCs) are known as erythrocytes (erythros = red). Red color of the red blood cell is due to the presence of the coloring protein pigment called haemoglobin. v They play a vital role in transportation of respiratory gases They are more than WBC and Platelets Normal Value: 4.0 - 5.5 million/cu mm of blood. In adult males - 5 million/mm3 and in adult females - 4.5 million/mm3 1. Disk shaped and biconcave (dumbbell shaped): Central portion is thinner and periphery is thicker Advantages of Biconcave Shape of RBCs 1. Biconcave shape helps in equal and rapid diffusion of oxygen and other substances into the interior of the cell. 2. It provides large surface area for absorption or removal of different substances. 3. It ensures minimal tension on the membrane 4. Ability to squeeze through the capillaries easily without getting damaged. v It lacks nucleus (non-nucleated - No DNA), Mitochondria and Golgi body v Lifespan of 120 days v Packed cell volume (PCV): Is the proportion of blood occupied by RBCs expressed in percentage. It is also called hematocrit value. It is 45% of the blood and the plasma volume is 55% Between the plasma and the red blood cells, there is a thin layer of white buffy coat; formed by white blood cells and platelets 1. Transport of: v Oxygen from the Lungs to the Tissues (Oxyhaemoglobin) v Carbondioxide from the Tissues to the Lungs (Carbhaemoglobin) 3. Buffering Action: Hemoglobin functions as a good buffer by regulating the hydrogen ion concentration and maintain acid-base balance 4. Blood Group Determination: RBCs carry the blood group antigens like A antigen, B antigen and Rh factor. WHAT IS THE FULL MEA NING OF PCV? WHAT IS THE DEFINITION AND ANOTHER NAME FOR IT? PROTEIN COLOURING PIGMENT IN BLOOD? WHAT IS PERCENTAGE AND COMPONENT OF BUFFY COAT? WHAT ARE THE TWO RESPIRATORY GASES? WHAT IS THE % OF PLASMA AND RBC RESPECTIVELY? Erythropoiesis is the process of production, development and maturation of erythrocytes (RBCs). It is also known as Hematopoiesis. SITE OF ERYTHROPOIESIS Stage of Life Duration Site/Structure of production Foetal stage First two months Mesenchyme of yolk sac Third month Liver (main organ) Spleen and lymphoid Fourth month Bone marrow and Liver Newborn and Children 1-20 years Bone marrow of long bones and flat bones Vertebra, sternum, Ribs, Scapula, Iliac Adults Above 20 years bones and Skull bones Stem cells called Haematopoietic Stem Cells are the primary cells capable of self-renewal and differentiating into specialized cells. Haematopoietic Stem Cells in bone marrow are uncommitted and are called uncommitted Pluripotent Haemopoietic Stem Cells (PHSC) PHSC is cell that can give rise to all types of blood cells. A cell becomes committed when the type of blood cells to produce has been determined i. e committed PHSC Committed PHSCs are of two types: 1. Lymphoid stem cells (LSC): Producese lymphocytes and natural killer (NK) cells 2. Colony forming unit cells (CFU): Which give rise to myeloid cells. Myeloid cells are the blood cells other than lymphocytes i.e Basophils, Eosinophils, Neutrophils Different units of colony forming cells are: i. Colony forming unit-erythrocytes (CFU-E) – Cells of this unit/group develop into erythrocytes ii. Colony forming unit-granulocytes/monocytes (CFU-GM) – These cells produce granulocytes (neutrophils, basophils and eosinophils) and monocytes iii. Colony forming unit-megakaryocytes (CFU-M) – These cells develop into platelets  STAGES OF ERYTHROPOIESIS 1. Proerythroblast 2. Early normoblast 3. Intermediate normoblast 4. Late normoblast 5. Reticulocyte 6. Matured erythrocyte  FACTORS NECESSARY FOR ERYTHROPOIESIS These factors are categorised into: 1. General factors 2. Maturation factors 3. Factors necessary for hemoglobin formation - Vitamins: Vitamin C, Riboflavin, Nicotinic acid (Niacin - B3) and Pyridoxine are also essential for the formation of hemoglobin. - Copper - Necessary for the absorption of iron from the gastrointestinal tract. - Iron - Necessary for the formation of heme part of the haemoglobin - Protein - Provided amino acids for the formation of protein component of haemoglobin  GENERAL FACTORS General factors necessary for erythropoiesis are: i. Erythropoietin - Produced by Kidney; Stimulant is Hypoxia (Low SPO2) ii. Thyroxine iii. Hemopoietic growth factors - Known as Growth inducers are the interleukins (IL 3, 6 and 11 ) and stem cell factor iv. Vitamins - Vitamin B, C, D and E  MATURATION FACTORS 1. Vitamin B12 (Cyanocobalamin) - It is transported to the bone marrow to promote maturation of RBCs It is essential for synthesis of DNA in RBCs Its deficiency leads to failure in maturation of the cell Deficiency of vitamin B12 causes pernicious anemia. So, vitamin B12 is called antipernicious factor. 2. Intrinsic Factor of Castle: Produced in gastric mucosa by the parietal cells of the gastric glands. Needed for the absorption of vitamin B12 from intestine  CLASS EXERCISE 1. State the importance of Vitamin B12 (Cyanocobalamin) 2. Deficiency of vitamin B12 causes ______ anemia. 3 ______ is needed for the absorption of vitamin B12 from intestine 4 _______ is produced by the kidneys during hypoxia  Erythrocyte Sedimentation Rate (ESR) v Erythrocyte sedimentation rate (ESR) is the rate at which the erythrocytes settle down. Also called Sedimentation rate, Sed rate or Biernacki reaction. v If blood is mixed with an anticoagulant and allowed to stand on a vertical tube, the red cells settle down due to gravity with a supernatant layer of clear plasma v It helps in diagnosis as well as prognosis of inflammatory diseases v ESR Values: Men ≤15mm/hr Female ≤ 20 mm/hr Child ≤ 10 mm/hr Newborn ≤ 0 - 2 mm/hr This is known as Leucocytes. Leuko is derived from Greek word leukos - white; cytes - cells (WBCs)  PROPERTIES OF WHITE BLOOD CELLS 1. Diapedesis: This the process by which the leukocytes squeeze through the narrow blood vessels. 2. Ameboid Movement: Neutrophils, Monocytes and Lymphocytes exhibit amebic movement, characterized by change in the shape. 3. Chemotaxis: Chemotaxis is the attraction of WBCs towards the injured tissues by the chemical substances released at the site of injury 4.Phagocytosis: Neutrophils and Monocytes engulf the foreign bodies by means of phagocytosis This is known as Leucocytes Leuko is derived from Greek word: leukos - white; cytes - cells (WBCs) They are classified into two: 1. Granulocytes: Have granules. Examples are: Basiphils, Eosinophils and Neutrophils 2. Agranulocytes: Do not have granules Examples are: Monocytes and Lymphocytes Depending upon the staining property of granules, the granulocytes are classified into three types: i. Neutrophils with granules taking both acidic and basic stains. ii. Eosinophils with granules taking acidic stain. iii. Basophils with granules taking basic stain. Agranulocytes have plain cytoplasm without granules. Agranulocytes are of two types: i. Monocytes ii. Lymphocytes  Ø BASOPHILS „ EOSINOPHILS Basophils also have coarse granules Eosinophils have coarse (larger) in the cytoplasm. The granules stain granules in the cytoplasm, which stain purple blue with methylene blue. pink or red with eosin. Nucleus is Nucleus is bilobed. Diameter of the bilobed and spectacle-shaped. Diameter cell is 8 to 10 µ. of the cell varies between 10 and 14 µ.  PLASMA Plasma is a straw-colored clear liquid part of blood. It contains 91% to 92% of water and 8% to 9% of solids. The solids are the organic and the inorganic substances Serum is plama without clotting factor (Fibrinogen) Serum = Plasma – Fibrinogen They are synthesized by: Mesenchyme cells - Foetal stage Reticuloendothelial cells of liver - Adult stage The three types are: 1. Serum albumin - Maintains Colloidal Osmotic Pressure 2. Serum globulin (Alpha, Beta and Gamma): Alpha and Beta: helps in transportation of sunstances while Gamma helps in body defence 3. Fibrinogen: Helps to clott blood to prevent blood loss. (It is a clotting factor) Plasma Components  FUNCTION OF PLASMA PROTEIN 1. Oncotic Pressure: Osmotic pressure exerted by proteins in the plasma called colloidal osmotic (oncotic) pressure pulls water (fluid) into the circulatory system(capillaries). It is about 25 mm Hg, and it is exerted by Albumin 2. Coagulation of blood: Fibrinogen is essential for the coagulation of blood 3. Defense against microbes and diseases: Gamma globulins play an important role in the defense by acting as antibodies (immunoglobulins) 4. Transport of substances in the blood: Albumin, alpha globulin and beta globulin are responsible for the transport of the hormones, enzymes, e.t.c 5. Maintenancw of Osmotic Pressure: Proteins exert the Colloidal Osmotic (oncotic) Pressure capillary level, which is about 25 mm Hg. Albumin → Globulin → Fibrinogen  FUNCTION OF PLASMA PROTEIN 6. Plasma protein is repsonsible for blood viscousity - Albumin 7. Plasma protein is repsonsible for Erythrocyte Sedimentation rate - Globulin and fibrinogen 8. Serve as source of energy: During fasting, inadequate food intake or inadequate protein intake, the plasma proteins are utilized by the body tissues as the last source of energy hyperproteinemia and hypoproteinemia \ „ MONOCYTES Monocytes are the largest leukocytes with diameter of 14 to 18 µ. The cytoplasm is clear without granules. Nucleus is round, oval and horseshoe shaped, bean shaped or kidney shaped. Nucleus is placed either in the center of the cell or pushed to one side and a large amount of cytoplasm is seen. \ The lymphocytes also do not have granules in the cytoplasm. Nucleus is oval, bean-shaped or kidney-shaped. Nucleus occupies the whole of the cytoplasm. Types of Lymphocytes Depending upon the function, lymphocytes are divided into two types: 1. T lymphocytes: Cells concerned with cellular immunity. 2. B lymphocytes: Cells concerned with humoral immunity \ Platelets known as thrombocytes are small, colorless and non-nucleated Platelets are responsible for blood clotting by forming Prothrombin Properties include: Diameter : 2.5 µ (2 to 4 µ); Volume : 7.5 cu µ (7 to 8 cu µ) Shape of Platelets - Normally, platelets are of several shapes, viz. spherical or rod- shaped and become oval or disk-shaped when inactivated. Inactivated platelets are without processes or filopodia and the activated platelets develop processes or filopodia- cellular protrusions containing bundles of actin filaments Lamellipodia help the platelets to cover the wounded area  NORMAL COUNT AND VARIATIONS \ Normal platelet count is 250,000/ mm3 of blood. It ranges between 2,00,000-4,00,000/cu mm of blood. „ PHYSIOLOGICAL VARIATIONS 1. Age: Platelets are less in infants and reaches normal level at 3rd month after birth 2. Sex: Same platelet counts between males and females In females, it is reduced during menstruation 3. High altitude: Platelet count increases. 4. After meals: After taking food, the platelet count increases. 1. Transportaion of respiratory gases - O2 and CO2 - Respiratory function 2. Transportaion of nutrients - Nutritive function 3. Transportaion of hormones and exzymes 4. Transportation of metabolic waste products - Excretory function 5. Regulation of body temperature - Homeosotatic function 6. Regulation of acid - base balance - Homeosotatic function 7. Regulation of water - balance - Homeostatic function 8. Protection against germs and diseases - Defensive function 1. Anaemia: Abnormal reduction in red blood cells count (PCV) and Hb, caused by haemorrhage and haemolysis. Types are: Aplastic anemia -Failure bone marrow cannot make enough new blood cells for your body Iron deficiency anemia - Caused by iron deficiency in the blood Sickle cell anemia - Caused by genetic changes (mutations) that lead to abnormal red blood cells and affect Hb gene Thalassemia - Low haemoglobin production Vitamin deficiency anemia - vitamin B-2, B-3, B-12 and folate. Vitamin deficiency anemia Vitamins necessary for erythropoiesis are: a. Vitamin B: Its deficiency causes anemia and pellagra (disease characterized by skin lesions, diarrhea, weakness, nervousness and dementia). b. Vitamin C: Its deficiency causes anemia and scurvy (ancient disease characterized by rough skin, bleeding gum, loosening of teeth, poor wound healing, bone pain, lethargy and emotional changes). c. Vitamin D: Its deficiency causes anemia and rickets. d. Vitamin E: Its deficiency leads to anemia and malnutrition. e. Vitamin B12: Requires for maturation of RBCs 2. Polycethemia 3. Leukemia: Leukemia is the condition which is characterized by abnormal and uncontrolled increase in leukocyte count more than 1,000,000/cu mm. It is also called blood cancer. 4. Leukopenia: Leukopenia is the decrease in total WBC count. 5. Cancer of the blood cells 6. Hypoxia 7. Haemorrhage 8. Hemopholia 9. Thallaseamia 10. Hemoglobinopathies - A genetic disorder caused by abnormal polypeptide chains of Hb.