Pharmacy Lecture: Blood Physiology PDF

Blood Physiology Dr. M. Abdelmohsen Assistant Professor of Physiology MBBCh, MSc, DMSc, DHPE Faculty of Pharmacy 2024-2025  Objectives ❖ At the end of this lecture, the 2nd year student...

Blood Physiology Dr. M. Abdelmohsen Assistant Professor of Physiology MBBCh, MSc, DMSc, DHPE Faculty of Pharmacy 2024-2025  Objectives ❖ At the end of this lecture, the 2nd year student should be able to: Discuss composition of blood Explain general functions of blood. Discuss erythropoiesis. Explain clotting mechanisms. Explain immunity and compare its types. Discuss pathophysiology of anemia. Explain pathophysiology of immunity. ❖ Composition of Blood: A) Plasma: fluid part of the blood. Mainly water (90%) and others (10%) Others are: 1) Plasma proteins: include the following: 1. Albumin: (most abundant). It is manufactured in liver, and it is important for maintaining blood osmotic pressure. 2. Globulin: formation of antibodies and carrier in blood. 3. Fibrinogen and prothrombin: Blood clotting factors are also manufactured in the liver. 4. Complement: they are enzymes help antibodies against pathogens. b) Nutrients: glucose, amino acids, small amount of lipids, mineral salts (chloride, carbonate, or phosphate salts of sodium, potassium, and magnesium) which function as: 1- Formation of bone 2- Production of hormones 3- Transportation of the gases (O2 and CO2) 4- Maintenance of acid base balance (Buffers) e.g., sodium bicarbonates. B) Cells or cell fragments: They are classified as follows: 1. Erythrocytes: (red blood cells) "RBCs" which transport oxygen. 2. Leukocytes: (White blood cells) "WBCs" which protect against infection. 3. Platelets (thrombocytes): they are cell fragments that participate in blood clotting. ❖ General functions of the Blood: 1. Transportation: a) Oxygen from inhaled air in the lung & carbon dioxide from the tissues to the lungs for elimination. b) Blood transports nutrients from the digestive system to the tissue cells. c) Blood transports waste products from the cells to the kidney and the liver. d) Blood carries hormones from their glands to the effector organs. 2. Regulation: a) Buffers in the blood help keep the PH of body fluids at about 7.4 b) Blood serves to regulate the amount of fluid in the tissues by plasma proteins that maintain the proper osmotic pressure c) Blood regulates body temperature by redistributing the excess heat. 3. Protection: a) Blood carries the cells and antibodies (immunity) that defend against pathogens. b) Blood contains clotting factors that protect against blood loss. ❖ Erythropoiesis: Definition: Production of mature RBCs (erythrocytes) from erythropoietic stem cell. Regulation of erythropoiesis: 1) Erythropoietin hormone: By feedback loop regulates erythropoiesis process. - Site of release: Mainly the kidney (more than 90 %) and liver in response to hypoxia (physiological e.g., fetus & high altitudes or pathological e.g., anemia). - In Anemia: As erythropoietin is bound by circulating RBCs. So, low circulating numbers of RBCs in case of anemia leads to a relatively high level of unbound erythropoietin, which stimulates more production of RBCs in the bone marrow. 2) Hepcidin: a recent discovered peptide (hormone) produced by the liver may play a role in erythropoiesis. It controls iron absorption in the gastrointestinal tract and iron release from reticuloendothelial tissue. ❖ Immunity: Definition: is the process of defense against invaders and pathogens. Types: 1- Innate (Natural) immunity: direct and rapid. Mechanisms: a) Skin prevents invasion of pathogens. b) Macrophages (Monocytes) and microphages (Mainly neutrophils & eosinophils) phagocytose the pathogens (bacteria) and destruct it. c) Natural killer (NK) cells (type of T cells) is natural cytotoxic to infected cells. 2- Adaptive (acquired) immunity: indirect and slower. - More effective and produce memory cells for the next same pathogen (as in previous same infection or vaccination). Mechanisms: a) Humoral: Antibodies produced by B lymphocytes to fix antigens of pathogen directly. b) Cell-mediated: through T lymphocytes via: 1- Helper T cells (CD4): Identification of antigen presented cells (APC) to help phagocytosis of these infected cells. 2- Cytotoxic T cells (CD8): Destroy the cells contains the antigen. ❖ Blood Clotting: (Intrinsic or Extrinsic pathways): - Coagulation: Protective mechanism prevents blood loss from injured blood vessel. - Clotting factors are normally inactive in the blood stream. - Procoagulants: are compounds promote clotting - Anticoagulants: are copunds prevent clotting. - Thrombolytics: are circulating chemicals dissolve clots. - All are normally in balance. Clotting steps: Injured tissues release → thromboplastin → reacts with proteins (clotting factors) and calcium → prothrombin activator → reacts with calcium → convert prothrombin to thrombin → thrombin converts soluble fibrinogen into insoluble fibrin → forms a network of threads that entraps red blood cells (the clot). ❖ Pathophysiology: ❑ Anemia: Definition: Lack enough healthy RBCs or Hb to carry adequate oxygen to tissues. Causal types of anemia: 1. Aplastic anemia: bone marrow insufficiency. All blood cells decrease. 2. Iron deficiency anemia. 3. Sickle cell anemia: the shape of RBC is sickle (type of hemolytic anemia). 4. Thalassemia: genetic abnormality of alpha or beta subunit of hemoglobin 5. Vitamin deficiency anemia: e.g., vitamin B12 (pernicious anemia) & folic acid deficiency (megaloblastic anemia). Analytical (laboratory) types of anemia: 1- Microcytic hypochromic anemia: iron deficiency and chronic blood loss. 2- Normocytic normochromic anemia: Acute blood loss. 3- Macrocytic anemia: vitamin B12 & folic acid deficiency. Symptoms & signs of anemia: - Fatigue - weakness - pale or yellowish skin. - Irregular heartbeats - shortness of breath. - Headaches -dizziness - Chest pain - Cold hands and feet. Complications: Extreme fatigue, pregnancy complications, heart problems. Prevention & treatment: 1. Iron: Iron-rich foods (liver beef and meats, beans, lentils & iron-fortified cereals). 2. Folate: fruits and fruit juices, dark green leafy vegetables, bread, cereal, pasta and rice. 3. Vitamin B-12: meat, dairy products, fortified cereal and soy products. 4. Vitamin C (increase iron absorption): citrus fruits and juices, broccoli, melons, and strawberries. 5. Drugs & supplementations: all nutrients can be given as supplementation.. ❖ Pathophysiology: ❑ Immunity diseases: Hypersensitivity reactions: exaggerated response of immune system to an antigen that cause tissue damage. Types of hypersensitivity reactions: Type-I (Immediate Hypersensitivity Reaction): over production of IgE e.g., bronchial asthma, allergic rhinitis, and contact dermatitis. Type-II (Cytotoxic Hypersensitivity): IgG type reacts with cell antigen. e.g., Autoimmune hemolytic anemia, erythroblastosis fetalis, and Drug- induced hemolysis. Type-III (Immune complex disease): formation of antigen-antibody complexes. e.g., tissue destruction (vascular injury). Type-IV (Cell-Mediated Hypersensitivity or delayed type): sensitized T- lymphocytes. e.g., contact dermatitis.  Immuno-deficiency diseases: 1. Primary immune-deficiency diseases: early childhood (genetically determined) Deficiencies of antibody (B-cells). Deficiency of cell-mediated (T-cells) Combined T-cells and B-cells Deficiency (Severe disease) Complement factor deficiency. 2. Secondary immuno-deficiency diseases: - Deterioration in previously strong immune status. - Occur secondary to systemic conditions like: - ▪ Diabetes mellitus ▪ Cancer ▪ Human Immuno-deficiency Virus (HIV/AIDS). ▪ Renal failure, Liver failure, Poor nutrition.  Thank You Faculty of Pharmacy 2024-2025