BIOL 122 Chapter 19: Blood
BIOL 122 Chapter 19: Blood BIOL 122
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This 10 page Class Notes was uploaded by Bridget Notetaker on Thursday February 4, 2016. The Class Notes belongs to BIOL 122 at University of Southern Indiana taught by Dr. Pilcher in Spring 2016. Since its upload, it has received 14 views. For similar materials see Human Anatomy & Physiology II in Biology at University of Southern Indiana.
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Date Created: 02/04/16
Chapter 19: Blood Thursday, February 4, 20164:18 PM Functions of blood Transport/distribution Regulation Protection Components of blood Plasma High protein liquid Formed elements Erythrocytes (hematocrit) 45% Red blood cells Leukocytes and platelets Buffy coat In between plasma and RBC's White blood cells Formed elements Erythrocytes Anuclear No nucleus Transport of oxygen Leukocytes Large, nucleated cells Immune function Platelets Cell fragments Blood clotting Plasma Water 91% Proteins 7% Albumin 58% Primary source of osmotic pressure Globulins 38% Antibodies in blood Fibrinogen 4% Converted to fibrin Basis of blood clotting Plasma minus clotting proteins = serum Globulins 38% Antibodies in blood Fibrinogen 4% Converted to fibrin Basis of blood clotting Plasma minus clotting proteins = serum Waste products Ions, gases Nutrients Regulatory substances (hormones) Introduction to leukocytes Least numerous formed element (compared to RBS's) Mostly occur in tissues Large, sometimes elaborate nuclei Function of leukocytes Defense against pathogens Specific role is different for each type of white blood cell Response against pathogens Amoeboid motion, diapedesis, positive chemotaxis Diapedesis: squeeze out of capillaries between adjacent blood vessel cells Positive chemotaxis: something 'a cell' being attracted to a chemical Amoeboid motion: crawlin -ype of movement accomplished by protrusion of cytoplasm of the cell Classification of leukocytes Granulocyte vs. agranulocyte Granulocytes have visible granules in the cytoplasm Staining: wright strain Granulocytes Neutrophils 50-‐70% of WBC's Polymorphonuclear cells (PMN's) Nucleus is made up 3 lobes 4 Staining of granules make cytoplasm lilac Function Phagocytosis of bacteria (acute bacterial infections) Engulf and destroy bacteria Role in inflammatory responses Eosinophils 2-‐4% of leukocytes Granules stain brick red to crimson in eosin stain Nucleus has 2 lobes connected by band of nucleus Function in inflammation and in immune responses to parasitic worms Basophils Eosinophils 2-‐4% of leukocytes Granules stain brick red to crimson in eosin stain Nucleus has 2 lobes connected by band of nucleus Function in inflammation and in immune responses to parasitic worms Basophils Rare: 0.5% of leukocytes Granules stain dark purple in basic dyes U or S shaped nucleus, though obscured by granules Involved in inflammatory responses: secretes histamine (vasodilator) and heparin (anticoagulant) Agranulocytes Lymphocytes 20-‐25% of leukocytes Close to size of RBC's Rounded or kidney-‐shaped nucleus; may have only crescent of cytoplasm visible Functions Found mostly in tissues B lymphocytes: antibody production, immune response, etc. T lymphocytes: directly destroy foreign cells, etc. Monocytes 3-‐8% of leukocytes Largest WBC type U or kid-‐shaped nucleus Function: differentiate into macrophages (big eater) in the tissues (phagocytic cells) Description of erythrocytes Biconcave The 2 sides of the cell are indented Anucleated No nucleus Flexible plasma membrane Allows RBC's to pass through capillaries 7.5 micrometers long 2.0 micrometers tall Suitability of structure Large surface area to volume ratio Ensures that there is plenty of space for oxygen to diffuse through the plasma membrane and gain entry to the interior of the cell Mostly hemoglobin (Hb) in cytoplasm Short distance from plasma membrane Few organelles Use anaerobic fermentation (does not use the transported oxygen) Role in blood viscosity Mostly hemoglobin (Hb) in cytoplasm Short distance from plasma membrane Few organelles Use anaerobic fermentation (does not use the transported oxygen) Role in blood viscosity Viscosity -‐how thick or sticky a substance is Functions of erythrocytes Oxygen transport Carbon dioxide transport Role of hemoglobin Roughly 98% of oxygen is bound to hemoglobin Hemoglobin Pigment molecule Protein that absorbs light Carries most O2 and some CO2 Structure of hemoglobin Four protein chains: globin Each chain contains a heme group with a ferrous ion (iron) Each heme group binds one oxygen Gas transport by hemoglobin Heme: one O2 per heme (max of O2 per hemoglobin molecule) Globin: contains CO2 binding sites Oxyhemoglobin: ruby red Deoxyhemoglobin: dark red Carbaminohemoglobin: CO2 binds easier to deoxyhemoglobin than to oxyhemoglobin Clinical values Hematocrit (packed cell volume) Hematocrit Is the PERCENT of total blood volume that is RBC Males: 40-‐54% Females: 3047% Hemoglobin concentration Males: 14-‐18 g/100 mL of blood Females: 1216 g/100 mL of blood RBC count Males: 4.-‐6.2 million/mm^3 Females 4.25.4 million/mm^3 Hematopoiesis Leukopoiesis, erythropoiesis, thrombopoiesis In red bone marrow Common stem cell: hemocytoblast Hormonal regulation Colony stimulating factors (CSF's) Hematopoiesis Leukopoiesis, erythropoiesis, thrombopoiesis In red bone marrow Common stem cell: hemocytoblast Hormonal regulation Colony stimulating factors (CSF's) Erythropoietin Hemocytoblasts Differentiate into lymphoid or myeloid stem cells Leukopoiesis: WBC's Stages Lymphoid line becomes lymphocytes T lymphocyte precursors leave bone marrow; differentiation occurs in thymus B lymphocyte precursors remain in bone marrow Myeloid stem cell line Could become erythrocyte, mega curiocyte which forms platelets or one of the granulocytes, or monoblast that forms a monocyte Stages Myeloid line develops into granulocytes and monocytes Production of granuloctes Myeoblast Progranulocyte Myelocyte Band cells (may be released into blood at this point) Final stages: nuclei become segmented Production of monocytes Monoblast Promonocyte Monocyte (released into the blood) Leukocyte abnormalities Leukocytosis: high number of WBC's Leukopenia: low number of WBC's Leukemia Cancer of hemopoietic tissues (high WBC numbers) Erythropoiesis -‐RBC's Production of erythrocytes within red bone marrow A type of hematopoiesis or hemopoiesis Stages Hemocytoblast Myeloid stem cell Committed cell type Proerythroblast Stages Hemocytoblast Myeloid stem cell Committed cell type Proerythroblast Early and late erythroblasts Reticulocytes Mature erythrocytes Trends Cell is getting smaller Nucleus gets smaller than extruded Color in the cytoplasm changes Regulation of erythropoiesis Erythropoietin (EPO) From kidneys/liver In response to hypoxia (inadequate O2) due to: Reduced RBC count; insufficient hemoglobin per RBC Reduced oxygen available Increased tissue demands Adequate "raw" material Iron, B vitamin-B2, folic acid) Other influences Testosterone Erythrocyte destruction (RBC recycling) Hemolysis After approximately 120 days Cell fragments phagocytized in liver or spleen Hemoglobin broken down by macrophages and recycles Erythrocyte life cycle -‐Hemoglobin is broken down by macrophages into heme and globin chains -‐The globin chains of hemoglobin are broken down to individual amino acids and are metabolized or used to build new proteins -‐The heme of hemoglobin releases the iron -‐Blood transports iron in combination with transferrin to various tissues for storage or to the red bone marrow where it's used in the production of new hemoglobin -‐Blood transports free bilirubin to the liver -‐Conjugated bilirubin is excreted as part of the bile into the small intestine. Bacteria of the small intestine break down the bilirubin -‐Some bilirubin derivatives contributes to the color of feces -‐Other bilirubin derivatives are reabsorbed from the intestine into the blood. These derivatives are excreted from the kidneys and contribute to the color of urine Erythrocyte disorders (table 19.4 pg. 600) Bacteria of the small intestine break down the bilirubin -‐Some bilirubin derivatives contributes to the color of feces -‐Other bilirubin derivatives are reabsorbed from the intestine into the blood. These derivatives are excreted from the kidneys and contribute to the color of urine Erythrocyte disorders (table 19.4 pg. 600) Erythrocytosis (polycythemia) Elevated RBC count More cells in less water Anemia No blood Reduced O2 carrying capability Iron-‐deficiency anemia Hemorrhagic anemia Hemolytic anemia Abnormal hemoglobin Thalassemia and sickl-‐cell trait/disease Platelets Cell fragments from megakaryocytes Function Blood clotting (hemostasis) Secrete various chemical messengers: Clotting factors Vasoconstrictiors Chemotaxic compounds Growth factors (aid in healing) Thrombopoiesis: platelets Formation of platelets Hormone: thrombopoietin Committed cell: megakaryoblast Platelets break away from megakaryocytes Stored in spleen or circulate in-d (ays) d Hemostasis Stopping blood loss Mechanisms of hemostasis Vascular spasm Platelet plug formation Coagulation PLATELETS ARE CRITICAL Vascular spasm First defense against blood loss Involves constriction of broken blood vessels Mechanisms Coagulation PLATELETS ARE CRITICAL Vascular spasm First defense against blood loss Involves constriction of broken blood vessels Mechanisms Vascular smooth muscle contraction Vasoconstrictor chemicals released from platelets and endothelial cells Neural: stimulation of pain receptors stimulates reflex vasoconstriction Platelet plug formation Platelets adhere to exposed collagen fibers in damaged vessel wall Role of von willebrand factor Swell, from spiky extensions, become > a re activated Platelet release reaction (degranulation) During PRR, ADP, thromboxanes, and other chemicals are released and activate other platelets Vasoconstriction (serotonin, thromboxane A2) Chemotaxic compounds (ADP, thromboxane A2) Attract more platelets which bind to a plug Causes release reaction in additional platelets Positive feedback -‐ -‐> platelet aggression Platelet plug fills gap Temporarily stops blood leakage Coagulation Clotting of blood (from liquid to gel) Production of fibrin from plasma fibrinogen Fibrin forms web of fibers Traps RBC's, etc. Forms clot Coagulation cascade Coagulation occurs as a cascade Production of fibrin from plasma fibrinogen Fibrin forms web of fibers Activation of factor X (10) Intrinsic and extrinsic pathways Leads to common pathway Extrinsic mechanism Initiated by clotting factors released by blood vessel wall and surrounding damaged tissue Tissue factor (factor III, or tissue thromboplastin) from injured cells Intrinsic mechanism Clotting factors all originate within blood Binding to factor XII to surface of platelets of plug Cascade continues until activation of factor X Common pathway to thrombin Tissue factor (factor III, or tissue thromboplastin) from injured cells Intrinsic mechanism Clotting factors all originate within blood Binding to factor XII to surface of platelets of plug Cascade continues until activation of factor X Common pathway to thrombin Factor X eventually leads to production of thrombin Thrombin causes activation of fibrinogen to fibrin and formation of the clot Formation of clot Cross linking of fibrin due to- X I abilized clot Control of clot formation Factors limiting abnormal clot formation and growth Smooth endothelial linin -> no place for platelets to adhere Inhibition of activated clotting factors Thrombin restricted to clot Bound to fibrin Inactivated if it enters blood flow (plasma protein called antithrombin III) Anticoagulants in plasma Smooth removal of clotting factors (due to blood circulation) Clot retraction Clot retraction Contraction of platelet extensions Pulls edges of wound together Promotes healing Reduces risk of infection Clot dissolution Fibrinolysis Cascade Plasminogen from plasma is trapped in clot Factors such as tissue plasminogen activator from endothelial cells convert plasminogen to plasmin Plasmin production also due to thrombin and activated factor XII Plasmin breaks up clot Coagulation disorders Thrombosis Abnormal blood clotting Thrombus (blood clot) can block small vessels Embolus: travels in blood steam to lodge elsewhere Thrombocytopenia Low platelet count (radiation, drugs, poisons, leukemia) Easy bruising Hemophilia Thrombus (blood clot) can block small vessels Embolus: travels in blood steam to lodge elsewhere Thrombocytopenia Low platelet count (radiation, drugs, poisons, leukemia) Easy bruising Hemophilia Deficiency of clotting factors Sex-‐linked heredity (occurs mostly in males)
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