Blood PDF - Generalidades

# SANGRE ## GENERALIDADES * The cardiovascular system is formed by 3 interconnected components: blood, heart, and blood vessels. * The branch that studies blood is called hematology. ## FUNCTIONS AND PROPERTIES OF BLOOD: * Blood is a connective tissue composed by a fluid cellular matrix called p...

# SANGRE ## GENERALIDADES * The cardiovascular system is formed by 3 interconnected components: blood, heart, and blood vessels. * The branch that studies blood is called hematology. ## FUNCTIONS AND PROPERTIES OF BLOOD: * Blood is a connective tissue composed by a fluid cellular matrix called plasma, in which cells and cell fragments are found. * The interstitial fluid bathes the cells and is constantly renewed. * Functions: * **Transport:** O2 from lungs to cells and CO2 from cells to lungs. * **Regulation:** homeostasis of fluids, regulates pH by means of buffers, body temperature, and also regulates osmotic pressure. * **Protection:** through coagulation, it protects against bleeding and through white blood cells, antibodies, and interferons, it protects against pathogens. ## CHARACTERISTICS OF BLOOD: * Dense, viscous, with a temperature of 38°C, slightly alkaline pH 7.35-7.45, red color, represents 20% of ECF and 8% of total body mass, and volume: 5-6 L for men and 4-5 L for women on average. * Components: * **Plasma:** Aqueous extracellular matrix. * **Formed elements:** 45% (99% are red blood cells and 1% are white blood cells). * **Plasma represents 55% of blood:** 91.5% water and 8.5% solutes (7% proteins and 1.5% others). * **Proteins in plasma (synthesized by hepatocytes):** albumin 54%, globulins 38%, fibrinogen 7%, antibodies or immunoglobulins. * **Formed elements:** 3 main types: red blood cells, white blood cells, and platelets. * **White blood cells classification:** Granulocytes: neutrophils, eosinophils, and basophils. * **Agranulocytes:** T and B lymphocytes, Natural Killer cells, and monocytes. ## HEMATOCRIT: * The percentage of total volume occupied by red blood cells. Its values are: women 38%-46%, men 40-54%. * Due to testosterone (higher in men) stimulating the synthesis of EPO, the hormone that stimulates red blood cells. * Anemia means a decrease of red blood cells. * Polycythemia means a high percentage of red blood cells, greater than 65%. ## FORMATION OF BLOOD CELLS: * The process known as hematopoiesis. * It first occurs in the yolk sac, then the liver, spleen, and thymus. * The main hematopoietic organ is the red bone marrow, highly vascularized, located between the trabeculae of spongy bone, axial skeleton. * 0.05-0.1% of cells derived from mesenchymal cells are called pluripotent stem cells or hemoblasts. * These proliferate and differentiate into 2 types of stem cells: myeloid stem cells and lymphoid stem cells (T and B lymphocytes, NK lymphocyte). ## GLOBULOS ROJOS * The red blood cell contains a protein transporter of oxygen called hemoglobin. * Men have 5.4 million per micro/L of Hb and women have 4.8 million of Hb per ul. * They are biconcave, 7-8 micrometers in diameter, have no nucleus or organelles. * Function: oxygen transport. * They generate ATP anaerobically, each red blood cell contains 280 million molecules of hemoglobin. * Hemoglobin is composed of globin, 2 alpha chains and 2 beta chains, and a non-protein heme group. * The center of the heme ring has Fe2+ that binds reversibly with O2. * Hemoglobin carries 23% of all CO2. * Hemoglobin is involved in regulation of blood flow, blood pressure, and releases nitric oxide that causes vasodilation. * They live 120 days and are lisated in the liver and spleen. * Hemoglobin is separated into a heme portion (Fe2+) and globin (amino acids), Fe2+ is transported by transferrin, and stored as ferritin in the spleen, liver, and muscles. * Required for the production of red blood cells: Fe2+, amino acids and Vitamin B12. * The non-heme portion is converted into biliverdin, then into bilirubin (in the liver it is converted into bile), in the large intestine, bacteria convert it into urobilinogen and later into urobilin, which gives the urine a yellowish pigmentation. * Stercobilin gives the fecal material a brown pigmentation. * Hypoxia stimulates an increase in the renal release of EPO. * The liver produces most of the EPO during the first weeks. ## GLOBULOS BLANCOS * Classified as granular (neutrophils, eosinophils, and basophils) and agranular (lymphocytes and monocytes). ## LEUCOCITOS GRANULOCITOS * **Neutrophils (60-70%):** their granules do not strongly attract acid (red) and basic (blue) dyes. They have a nucleus with 2-5 lobes. They are also called polymorphonuclear and increase during bacterial infections. * **Eosinophils (2-4%):** have granules with an affinity for eosin, but do not cover the nucleus. * **Basophils (0.5-1%):** affinity for basic dyes, darken the nucleus. ## LEUCOCITOS AGRANULARES * **Lymphocytes (20-25%):** 6-9um small, 10-14um large. * **Diagnostic importance in viral infections and immunodeficiencies.** * **Monocytes (3-8%):** kidney/horseshoe-shaped nucleus, azurophilic granules, differentiate into macrophages in tissues, fixed or circulating (accumulate in foci of infection). MHC antigens (major histocompatibility complex) are "cell identity markers" not present in red blood cells. ## FUNCTION OF WBC: * Protection, 5000-10000 cells per micro/L. * **Leukocytosis:** increase in white blood cell count, >10,000 per microliter. * **Leukopenia:** decrease in white blood cell count, < 5,000 per microliter. * Only 2% of total lymphocytes circulate in the blood, the rest are in the lymph, skin, lungs, lymph nodes, and spleen. * They leave through migration/diapedesis. * **Neutrophils and macrophages are phagocytic.** * **Chemotaxis:** substances that attract phagocytes. * **Neutrophils:** respond faster, they release lysozyme and strong oxidants (H2O2, OCl-, O2-) and defensins "spears" (phagosomes). * **Basophils:** release heparin, histamine, and proteases, they are responsible for hypersensitivity (allergies). * **Lymphocytes:** * **B cells:** destroy bacteria and inactivate toxins. * **T cells:** attack viruses, fungi, cancer cells, and transplanted cells. * **NK cells:** destroy a variety of microbes. * **Monocytes:** take longer to arrive than neutrophils at the site of infection, but in larger amounts. * At the site of infection, monocytes differentiate into macrophages. ## PLAQUETAS * They are actually cell fragments. * There are between 150,000-400,000 per ul. * They have a disc shape of 2-4 um in diameter and many vesicles. * They promote blood coagulation and the formation of the platelet plug. * They have a short lifespan of 5-9 days, dead and aged platelets are removed by splenic and hepatic macrophages. ## TRANSPLANTATION OF BONE MARROW STEM CELLS AND UMBILICAL CORD BLOOD * Bone marrow transplantation involves replacing abnormal or cancerous bone marrow, provided by a donor. * It is useful for treating aplastic anemia, leukemia, Hodgkin's disease, and non-Hodgkin's lymphoma. * You can also obtain stem cells from umbilical cord blood. ## HEMOSTASIS * It is the process that stops bleeding, and is achieved through three mechanisms: * **Vasoconstriction:** * Consists of the contraction of the vessel wall that was injured. * It reduces blood loss for minutes up to hours. * **Platelet Plug Formation:** * It takes place in three steps: 1. **Platelet adhesion:** Platelets adhere to the area of vessel injury. 2. **Platelet release:** Platelets release the contents of their vesicles, ADP and thromboxane A2 (activate nearby platelets), serotonin and thromboxane A2 (vasoconstriction). 3. **Platelet aggregation:** (thanks to ADP) in mass, called the platelet plug. * **Coagulation:** * It is a complex cascade of enzymatic reactions. * Prothrombinase converts prothrombin into thrombin, and this converts soluble fibrinogen into insoluble fibrin. * There are two coagulation pathways: 1. **Extrinsic pathway:** it is fast and simple, named for the tissue factor, also known as thromboplastin, which leaks from outside the blood vessels. It initiates a sequence of reactions that activates factor X and combines with factor V to form prothrombinase in the presence of calcium ions. 2. **Intrinsic pathway:** it is slow and complex. It starts when blood comes into contact with collagen fibers. It activates factor XII, which then activates factor X, that combines with factor V to activate prothrombinase. 3. **Common Pathway:** Prothrombinase converts prothrombin into thrombin, which, in the presence of calcium ions, converts fibrinogen into fibrin. Thrombin also activates factor XIII, which strengthens and stabilizes the fibrin mesh. | Number | Name | Source | |---|---|---| | 1 | Fibrinogen | Liver | | 2 | Prothrombin | Liver | | 3 | Tissue factor or thromboplastin | Platelets | | 4 | Calcium ion | Platelets | | 5 | Proaccelerin | Liver and platelets | | 6 | Stable factor or proconvertin | Liver | | 7 | Antihemophilic factor A or antihemophilic globulin | Liver | | 8 | Christmas factor or antihemophilic B | Liver | | 9 | Stuart-Prower factor | Liver | | 10 | Antihemophilic factor C | Liver | | 11 | Hageman factor or antihemophilic D | Liver | | 12 | Fibrin stabilizing factor | Liver and platelets | ## RETRACTION OF THE CLOT: it is the consolidation or increase in the tension of the fibrin clot, which depends on the adequate amount of platelets. Vitamin K, important for coagulation, is produced by microorganisms in the large intestine, and it is fat-soluble. ## FIBRINOLYSIS: * The formation of an inadequate clot is dissolved through the fibrinolytic system. * Plasminogen is converted into plasmin, which degrades fibrin. * Prostacyclin is a potent inhibitor of platelet aggregation, leading to the anticoagulant effects of medications like antithrombin (blocks factors XII, X, and II) and heparin (enhances the effects of antithrombin), and the activated protein C inactivates coagulation factors. ## INTRAVASCULAR COAGULATION: formation of clots inside the bloodstream. * **Thrombosis:** coagulation in a blood vessel. * If it does not dissolve, it can detach and become an **embolus**. ## BLOOD GROUPS AND BLOOD TYPES * ABO Blood Group: It is based on two glycolipid antigens, A and B. * **Blood Type A:** They express only antigen A on their red blood cells. * **Blood Type B:** They express only antigen B on their red blood cells. * **Blood Type AB:** They express both A and B antigens. * **Blood Type O:** They do not express A or B antigens, making them universal donors. * **Antibodies:** * Type A individuals have anti-B antibodies in their plasma. * Type B individuals have anti-A antibodies in their plasma. * Type AB individuals have neither anti-A or anti-B antibodies. * Type O individuals have both anti-A and anti-B antibodies. * **Blood Transfusion:** It is the transfer of whole blood or components into the bloodstream or bone marrow. * **Incompatibility Issues:** If incompatible blood is transfused, agglutination and hemolysis occur. * **Rh Factor:** Rh+ blood expresses Rh antigen, while Rh- blood does not. * **First Exposure to Rh+ Blood in Rh- Individuals:** Rh- individuals do not have anti-Rh antibodies in their plasma. * **Second Exposure to Rh+ Blood in Rh- Individuals:** Anti-Rh antibodies will develop, which could cause agglutination and hemolysis.