Blood & plasma proteins MSc DAN 2024-25_240906_162855[1].pdf

06-09-2024 Blood – Part 1 B...

06-09-2024 Blood – Part 1 Blood is a fluid connective tissue present in the circulatory system Normal blood volume in adult is around 5L 2.1. Explain the composition and functions of blood 2.2. Explain the individual functions of plasma proteins The pH of the blood is 7.4 2.3. Outline the salient structural features of red blood cells, production, life span, and destruction of red cells Blood is composed of formed elements (blood cells) suspended plasma 2.4. Describe briefly the structure, functions, normal value of haemoglobin, and the major causes of anemia Plasma is fluid portion (ECF) of the blood. It is around 3L Dr. Shreevatsa Bhat M Note: if blood is allowed to clot and the clot is removed, the remaining fluid is Division of Physiology called serum (Serum = Plasma – Clotting factors) Dept. of Basic Medical Sciences MAHE-Manipal [email protected] Composition of the blood Blood Formed elements (45%) Plasma (55%) Erythrocytes Leukocytes Thrombocytes Water (92%) Solids (8%) (RBCs) (WBCs) (Platelets) Organic Inorganic Granulocytes Agranulocytes Proteins Cl- Neutrophils Monocytes Lipids HCO3- Eosinophils Lymphocytes Glucose Na+ Basophils Urea K+, etc. Functions of blood Plasma proteins are the proteins present in the plasma. They constitute around Supply of nutrients 7% of the plasma Transport of respiratory gases (O2 and CO2) Most of the plasma proteins are synthesized in the liver and the circulating Transport of hormones, vitamins, drugs and chemicals antibodies are manufactured by lymphocytes Removal of waste products Protection against infection and immune response Types of plasma proteins (and their concentration): Regulation of body temperature Albumin (3.5 to 5.5 g/dL) Maintenance of acid-base balance Globulin: α-globulin, β-globulin and γ-globulin (1.3 to 2.5 g/dL) Helps in blood clotting, tissue repair and healing Storage function Fibrinogen (0.2 to 0.4 g/dL) Fluid balance and maintenance of blood pressure Prothrombin (0.1 g/dL) 1  06-09-2024 FUNCTIONS OF PLASMA PROTEINS 1. Exert colloidal osmotic pressure (oncotic pressure) 2. Contribution to blood viscosity 3. Role in coagulation of blood 4. Role in the defense mechanism of the body 5. Role in maintaining the acid-base balance of the body 6. Transport function 7. Role as reserve proteins 8. Role in suspension stability of red blood cells 9. Fibrinolytic function Molecular weights and shapes of different plasma proteins. 10. Role in Genetic Information 1. Plasma proteins exert oncotic pressure 5. Role in maintaining the acid-base balance (Buffering action) Normal oncotic pressure of 25 mmHg is maintained by plasma proteins Plasma proteins maintain pH at around 7.4 by accepting or donating H+ ions (mainly by albumin) 15% of the buffering capacity of blood is due to plasma proteins Play an important role in fluid exchange between the capillary and tissue. 6. Transport function 2. Contribution to blood viscosity Transports CO2, Ca2+, drugs, bilirubin, hormones, amino acids, steroids, vitamins, and fatty Mainly fibrinogen and globulin - due to their asymmetrical shape acids Maintenance of BP by providing resistance to the flow of blood Thyroxine transported by α-globulin (TBG) and cortisol by transcortin 3. Role in coagulation of blood Vitamin A, D, and E – by lipoproteins and vitamin B12 – by transcobalamin Fibrinogen and prothrombin are the clotting factors that play an important Bilirubin – by albumin and α globulin. role in hemostasis Copper – by ceruloplasmin (α2-globulin) Free Hb – by haptoglobin 4. Role in the defense mechanism γ-globulin are the immunoglobulins (antibodies) that protect the body against 7. Role as reserve proteins the invading organisms During fasting, inadequate protein intake and excessive protein catabolism Morphology and structural features of RBC The normal life span of RBC is 120 days Erythrocytes or RBCs are the most abundant cells present in the blood The RBC surface has a negative charge They are non-nucleated and they do not have mitochondria or ribosomes Red cell membrane undergoes mechanical and osmotic fragility RBC is a circular and biconcave in shape; red cells are elastic and can easily pass Red cells pile on top of each other (rouleaux formation), and sediment If blood through narrow capillaries with an anticoagulant is allowed to stand in a narrow vertical tube Normal mean red cell diameter is 7.2 µ The normal volume of RBC is 80 - 94 µm3 Rouleaux formation 2  06-09-2024 Functions of RBCs Red cell production: Stages of erythropoiesis Transport of O2 from the lungs to the tissues and CO2 from tissues to lungs Definition: Erythropoiesis is the process of formation and maturation of RBCs Regulation of acid-base balance A pluripotent hemopoietic stem cell, becomes a common myeloid progenitor Maintenance of viscosity of blood cell, and then a proerythroblast (unipotent stem cell) Normal erythrocyte count The proerythroblast undergo various changes during different stages of Males: 5 to 5.5 million cells/mm3 maturation. These changes involve, Gradual reduction in the cell size Females: 4.5 to 5 million cells/mm3 Disappearance of nucleolus and nucleus and, arrest of mitosis Infants: 6 to 7 million cells/mm3 Accumulation of hemoglobin Erythrocytosis: abnormally high RBC count Change in the staining property of cytoplasm Erythrocytopenia: abnormally low RBC count The process of erythropoiesis takes around 7 days Stages of erythropoiesis: Factors influencing erythropoiesis Proerythroblast Erythropoietin: Erythropoietin is a glycoprotein hormone formed in the kidney that stimulates erythropoiesis Early normoblastc It increases RBC production, enhances the Hb synthesis and hastens maturation of RBC In the bone marrow Dietary factors: Intermediate normoblast Iron: necessary for the synthesis of Hb Vitamin B12 : necessary for maturation of RBC Late normoblast Maturation factors Folic acid: necessary for maturation of RBC Reticulocyte Intrinsic factor: Released in to the circulation It is produced from the parietal cells of the gastric mucosa Erythrocyte It helps in the absorption of vitamin B12 Destruction of Red Blood Cells Hemoglobin Hemoglobin (Hb) is the iron containing protein Removal: present in the erythrocytes After 120 days, RBCs lose flexibility and are removed by macrophages in the spleen (main site), liver, and bone marrow. Each Hb molecule is made up of four heme groups surrounding a globin group Breakdown Process: Hemoglobin is broken down: There are four polypeptide chains, globins (α1, α2, β1, and β2) Heme releases iron (recycled) and is converted into bilirubin. Bilirubin is transported to the liver and excreted in bile. Each chain is attached to a heme group composed Globin proteins are broken down into amino acids and reused. of porphyrin attached to an iron atom Significance: This cycle helps maintain healthy RBC counts There are four iron atoms in each molecule of and prevents the toxic accumulation of old cells. hemoglobin, can bind four atoms of oxygen 3  06-09-2024 Functions of hemoglobin Normal value and variation of hemoglobin concentration Normal value Males: 14 to 18 g/dL Hemoglobin carries O2 from lungs to the tissues (1 gram Hb carries 1.34 mL Females: 12 to 16 g/dL of O2) Infants: up to 20 g/dL Variations of Hb level: It is involved in the transport of CO2 Decreased Hb Physiological : Lower in children, females and during pregnancy It acts as a buffer Pathological : Anemia Increased Hb Physiological : High altitude ( due to hypoxia) Pathological : Severe diarrhea, vomiting, polycythaemia vera, congenital heart disease and lung diseases Anemia and the types GENERAL CLINICAL FEATURES OF ANAEMIA Anemia is a clinical condition where in the RBC count or Hb level or both are decreased. The O2 carrying capacity is decreases in anemia General clinical manifestations of anemia that occur either due to tissue hypoxia or due to compensatory mechanisms are: Anemia classified depending on its etiology (cause) or morphology (red cell size and color) Generalized muscular weakness Pallorness of skin and mucous membranes Anemia Breathlessness Palpitation Etiological Morphological Visual disturbances Anorexia, atrophy of papillae on the tongue Increased Due to Microcytic Normocytic Macrocytic In females menstrual disturbances occur such as amenorrhoea and Decreased RBC RBC Blood loss hypochromic normochromic menorrhagia. formation destruction Etiological classification (depending on the cause) Morphological classification (depending on RBC size & color) Decreased RBC formation Increased RBC destruction Blood loss Microcytic Normocytic Macrocytic Iron deficiency anemic Thalassemia Acute blood loss hypochromic normochromic [RBCs are microcytic and Defect in globin chain of Hb Due to accidents, surgery RBC are smaller in size RBC are normal in size RBC are larger in size hypochromic] [RBCs are normocytic and Vitamin B12 & folic acid Sickle cell anemia normochromic] Hb content is reduced Hb content is also normal Hb content is normal deficiency anemia Abnormal Hb that is HbS type and RBCs look pale or reduced Chronic blood loss RBC number is reduced Megaloblastic anemia [RBCs are macrocytic and Peptic ulcers Hereditary spherocytosis normochromic] Biconvex RBCs Hemorrhoids E.g. iron deficiency anemia E.g. anemia due to hemorrhage E.g. Vitamin B12 deficiency anemia Pernicious anemia Hookworm infestation Intrinsic factor deficiency Glucose-6-phosphate Menstrual irregularities Aplastic anemia [RBCs are microcytic dehydrogenase deficiency hypochromic] Bone marrow suppression due to drugs, toxins or X-rays exposure 4