Gulf Medical University RBC and Anemia Lecture PDF

RBC and Anemia Dr.Rasha Eldeeb Associate Professor of Physiology www.gmu.ac.ae COLLEGE OF HEALTH SCIENCES  RBC and Anemia Learning Objectives: Define blood and its cellular and...

RBC and Anemia Dr.Rasha Eldeeb Associate Professor of Physiology www.gmu.ac.ae COLLEGE OF HEALTH SCIENCES  RBC and Anemia Learning Objectives: Define blood and its cellular and noncellular components. Explain the functions of blood Describe the plasma and its content Explain the functions of plasma proteins State the difference between the plasma and the serum Describe the RBC and relate its structure to the function. Define anemia and describe its different types according to the etiology and the morphology. State the Fate of Anemia. To Start with … What is Blood?  Blood Is the only fluid tissue in the body It is a specialized type of connective tissue in which living blood cells ( Red Blood cells, White blood cells and platelets) , are suspended in a nonliving fluid matrix called plasma It appears to be a thick, homogeneous liquid, the microscope reveals that it has both cellular and liquid components  Composition of the Blood Cellular component: 40-45% Cells (or corpuscles) Red blood corpuscles (R.B.Cs) or erythrocytes: about 5 millions/mm3. When decreased in number, the condition is called anemia, and when increased, it is called polycythemia White blood cells (W.B.Cs) or leukocytes: 4000-11000/mm3. When decreased in number, the condition is called leukopenia, and when increased, it is called leukocytosis Platelets or thrombocytes: 100000-400000/mm3. When decreased in number, the condition is called thrombocytopenia, and when increased, it is called thrombocytosis Liquid component: 55-60% (Plasma) Water (90%) Plasma proteins (7.1%) Lipids, hormones, enzymes, nutrients and waste products (2%) Various electrolytes e.g. Na+, K+, Cl-, HCO3-, Ca2+ and PO43- (0.9 %)  Plasma Proteins Types of plasma proteins: Albumin ranges from 3.5-5 g/dL (the average is 4 g/dL). Globulins [alpha (α), beta (β), and gamma (У)] range from 2.3-3.5 g/dL (the average is 2.7 g/dL). Fibrinogen is about 0.3 g/dL. Site of synthesis: All plasma proteins are synthesized in the liver except У globulins, which are synthesized by the B-lymphocytes and plasma cells Source of plasma proteins: The plasma proteins are normally formed from food proteins, and in starvation, they can also be formed from tissue proteins (reserve type) 100000-400000/mm3 4-5 millions/mm3 4000-11000/mm3 7 Serum= Plasma – Clotting Factors Now… What is RBC?  RBCs= Red Blood Corpuscles= Erythrocytes The RBCs is non nucleated , biconcave disc and formed of cytoplasm that has no mitochondria or cell organelles and is enclosed by a cell membrane. The biconcave shape is produced by 2 proteins in their membranes called ankyrin and spectrin. The cytoplasm is formed mainly (34%) of hemoglobin (Hb) as each RBC contains about 30 pg of hemoglobin (Hb). It also contains electrolytes (especially K+ & HCO3-) and several enzymes e.g. carbonic anhydrase & glucose-6-phosphate dehydrogenase (G-6-PD). What is the importance of the Biconcave shape in RBCs? oIt increases the surface area for diffusion of gases and decreases the distance that gases diffuse through it. oIt allows flexibility and shape change while squeezing through capillaries. oIt allows variations in the shape and dimensions of RBCs which is useful in the differential diagnosis of anemias.  RBCs The life span of RBCs is 120 days then destroyed and removed by the spleen. Red blood corpuscles (R.B.Cs) or erythrocytes: about 5 million/uL. Its Diameter is about 7 and its Volume is 90 3 Male: 4.7 to 6.1 million /uL Female: 4.2 to 5.4 million /uL. Why there is difference in Male and female in RBCs count? This is mainly due to difference in hormonal profile between the two genders , as male sex hormones, androgens, stimulate hemopoiesis) What are the Functions of RBCs? o The main function of RBCs is to transport hemoglobin, which in turn carries respiratory gases. o The hemoglobin in the RBCs is an excellent acid-base buffer , and responsible for most of the acid-base buffering power of whole blood. o The carbonic anhydrase, enzyme inside the RBCs catalyzes the reversible reaction between CO2 and water to form carbonic acid (H2CO3). o Essential for maintenance of diastolic arterial blood pressure. o The thin cell membrane allows free diffusion of O2 and CO2 in both directions, and the biconcave shape of the red cells provides the largest possible surface area for this purpose. o It plays an important role in producing blood viscosity, which is essential for maintenance of the diastolic arterial blood pressure. o Its membrane glycoprotein layer contains the specific agglutinogens that determine the blood group. What do we mean by Blood Group?  Two antigens (agglutinogen)—type A and type B—occur on the surfaces of the red blood cells in a large proportion of human beings Blood is normally classified into four major O-A-B blood types, depending on the presence or absence of the two agglutinogens, the A and B agglutinogens When neither A nor B agglutinogen is present, the blood is type O (Universal Donner). When only type A agglutinogen is present, the blood is type A. When only type B agglutinogen is present, the blood is type B. When both A and B agglutinogens are present, the blood is type AB (Universal Recipient). There are 6 common types of Rh antigens, each of which is called an Rh factor. These types are designated C, D, E, c, d, and e. If the person has Rh factor on his RBC cell membrane his blood type is Rh positive. What is the Importance of blood group?  In blood transfusion (to avoid incompatibility reactions) In marriage (to avoid erythroblastosis fetalis) http://t3.gstatic.com/images?q=tbn:pRVPq_xdAbMWUM:http://www.theodora.com/drugs/images/176.jpg Medicolegal importance; in cases of disputed paternity, blood grouping tests can only exclude paternity but can not prove it. http://t3.gstatic.com/images?q=tbn:r2uj8Zw7-n9r3M:http://divorcelawyers.co.za/wp-content/uploads/2010/08/paternity-test.jpg http://t3.gstatic.com/images?q=tbn:v7g7G9AtShMfnM:http://www.labworksfla.com/dna%2520strand.jpg How is RBCs Formed?  By Erythropoiesis It is the process of formation of RBCs. Where is the site of Erythropoiesis?  During Intrauterine Life: o 0-2 months (yolk sac), o 2-7 months ( liver, spleen), o 5-9 months (bone marrow) During the late months of Gestation and after birth: o Infants: bone marrow (practically all bones) o Adults: confined to the axial skeleton, proximal ends of the femur, and humerus- Extramedullary hemopoiesis can resume in the liver and spleen in diseases where the bone marrow is destroyed or affected by fibrosis. Active cellular marrow is called red marrow; inactive marrow that is infiltrated with fat is called yellow marrow What do we need for Erythropoiesis to occur?  The Bone Marrow: A healthy red bone marrow is essential for normal hemopoiesis Hormones Diet Diet containing: ▪ Proteins of high biological value. ▪ Minerals especially copper and cobalt ▪ Vitamins: Almost all vitamins are required Hypoxia particularly vitamin B12 and folic acid. (Maturation factors) Erythropoietin The liver: forms the globin part of Hb, stores vitamin B12 & iron, and secretes erythropoietin. Hormones: as androgens and thyroxin. Blood O2 Tension: Decreased O2 tension (hypoxia) stimulates erythropoiesis indirectly by stimulating the release of Erythropoietin What is the Fate of RBCs?  Life span of the RBCs in the bloodstream is 120 days. Old RBCs become rigid and fragile, and their hemoglobin begins to degenerate Dying erythrocytes are engulfed by macrophages and / or lysed mainly extravascularly in the reticuloendothelial system (Liver, Spleen, and Bone marrow)  The Variation In RBCs Count And Shape Anemia: the condition of decreased RBCs count Polycythemia: the condition of abnormally high hematocrit (High RBCs count in circulation) o Primary o Secondary Hereditary Spherocytosis: RBCs are spherocytic in normal plasma and hemolyze more readily than normal cells in hypotonic NaCl solutions. (Cell fragility), it is caused by abnormalities of the protein network that maintains the shape and flexibility of the red cell membrane So, Now… What Is Anemia?  Anemia means deficiency of hemoglobin in the blood which can be caused by either too few red blood cells or too little hemoglobin in the cells leading to decreased O2 carrying capacity of the blood and, thus, tissue hypoxia.  It is classified into A. Etiological Classification (B) Morphological Classification (According to the cause) (According to RBCs size and HB concentration) 1. Hemorrhagic anemia 1. Normocytic (blood loss) normochromic anemia 2. Decreased production of 2. Microcytic hypochromic RBCs anemia 3. Hemolytic anemia 3. Macrocytic normochromic anemia  Etiological Classification (1) Hemorrhagic anemia (blood loss) Caused by acute or chronic blood loss (e.g. epistaxis, bleeding esophageal varices or peptic ulcer, piles or bilharziasis) (2) Decreased production of RBCs A. Aplastic anemia: Bone marrow aplasia means lack of functioning bone marrow (bone marrow destruction) caused by radiation, chemotherapy, infection, malignancy (leukemia), and intoxication with drugs. B. Nutritional (deficiency ) anemia: iron deficiency anemia, vitamin B12 deficiency anemia ( megaloblastic anemia), Folic acid deficiency anemia  Etiological Classification (3) Hemolytic anemia:(excessive hemolysis (breakdown) of the RBCs) A. Corpuscular cause (congenital): Abnormalities in the red cell membranes e.g. congenital spherocytosis), Hemoglobinopathies e.g. sickle cell anemia and thalassemia), Deficiency of the G-6-PD enzyme B. Extracorpuscular causes (Acquired) Immune causes: Incompatible blood transfusion, Autoimmune hemolytic http://www.google.ae/images?q=tbn:Z6cypxnzUa8cXM::www.cartage.org.lb/en/themes/sciences/lifescience/generalbiology/physiology/LymphaticSystem/Antibodymediated/antigenAB.gift=1h=86w=128usg=__jq67j13JE58pWZgl3J29 anemia (i.e. formation of abnormal antibodies that attack the RBCs) Nonimmune causes: Infections e.g. malaria, Toxins e.g. snake venoms, Certain http://t3.gstatic.com/images?q=tbn:2bn7EwMasVqR6M:http://www.majidkareem.info/wp-content/uploads/2008/10/spleen.bmp drugs & chemicals, Hypersplenism  Morphological Classification It is classified according to the main 3 blood indices: Morphological Classification Morphological Classification  Morphological Classification 1- Normocytic normochromic anemia: Normal MCV (size of RBCs) and normal MCH and MCHC (amount of Hb in each RBC), but total RBC count is decreased. This is due to Acute blood loss (hemorrhage), Bone marrow depression, and Excessive hemolysis (destruction) of RBCs. 2- Microcytic hypochromic anemia: It is a type of anemia with small size of RBCs (MCV