Transcript Blood
Blood Anatomy & Physiology Functions of blood Transportation Heat regulation Composition of blood Made of plasma & formed elements Plasma: fluid portion of blood Formed elements Red blood cells (erythrocytes) White blood cells (leukocytes) Platelets (thrombocytes) Watch US blood cells clip Hematocrit or Packed Cell Volume (PCV) Percent of red blood cells in whole blood Buffy coat (less than 1%): white blood cells & platelets Erythrocytes (RBCs) Mature RBC has no nucleus, ribosomes, mitochondria Small biconcave discs Primary component: hemoglobin (1/3 of cell volume) Flexible because of stretchable fibers called spectrin Function of RBCs Transportation of oxygen & carbon dioxide depends on hemoglobin & an enzyme carbonic anhydrase Hemoglobin 200-300 million molecules of hemoglobin in each RBC Each hemoglobin molecule contains 4 protein chains called globin & each chain is bound to a red pigment, heme, which each heme contains an iron molecule One hemoglobin molecule can unite with 4 oxygen molecules Erythropoiesis Formation of RBC Begins in the bone marrow from hematopoietic stem cells which form all blood cells In series of steps lose nuclei to become reticulocyte which is released into circulation which become mature RBC which is smaller Erythropoietin Hormone released by the kidney when blood oxygen levels decline which then stimulates the bone marrow to increase production of RBCs Destruction of RBCs Life span of RBC is about 105-120 days Macrophages in lining of blood vessels in spleen & liver phagocytose old or damaged RBC Hemoglobin broken down & amino acids, iron & pigment bilirubin released Iron used to form new hemoglobin & bilirubin transported to liver & excreted into the intestines in bile Leukocytes (WBCs) 5 types All have nuclei Larger than RBCs Granulocytes (have large granules in cytoplasm) Neutrophils Eosinophils Basophils Agranulocytes Lymphocytes Monocytes Neutrophils About 65% of the total WBC count Multilobed nucleus Small light purple granules in cytoplasm Function: cell defense by phagocytosis of microorganisms Life span: hours to 3 days Eosinophils Usually 2 lobed nucleus Large orange-red staining granules Function: cellular defense usually against parasites & involved in allergic reactions Life span: 10-12 days Basophils Usually 2 lobed nucleus Sparse, large purple staining granules Least numerous WBC Function: secrete heparin & histamine Life span: hours to 3 days Lymphocytes Smallest of WBC, about 25% of total WBC count Large spherical nuclei with scant pale blue cytoplasm T-lymphocytes: directly attack infected or cancerous cell B-lymphocytes: produce antibodies against specific antigens Life span: days to years Monocytes Largest of the WBC Kidney bean shaped nuclei with large quantities of blue-gray cytoplasm Phagocytic cell capable of ingesting bacteria, debris, cancerous cells In tissue called macrophages Life span: months WBC Formation Neutrophils, eosinophils, basophils originate in bone marrow Most lymphocytes & monocytes originate in lymphatic tissue Watch US platelets clip Platelets Small, nearly colorless, irregular 3 important physical properties Agglutination Adhesiveness Aggregation Functions of platelets Hemostasis: stoppage of blood flow Damage to blood vesselsvascular spasm temporary platelet plug by sticky platelets secrete ADP, thromboxane & fatty acid (arachidonic acid) which are involved in coagulation Coagulation: blood clotting Formation & Life Span of Platelets Formed in bone marrow, lungs & spleen by fragmentation of very large cell, megakaryocyte Life span: 7 days Watch US blood type clip Blood Types Refers to the type of antigens, called agglutinogens, present on RBC membrane Important blood antigens: A, B, Rh Agglutinins: antibodies dissolved in plasma that react with specific blood group antigens ABO System Type A: Antigen A on RBCs Type B: Antigen B on RBCs Type AB: Antigen A & B on RBCs Type O: Neither A nor B on RBCs Plasma never contains Ab against Ag present on it own RBCs Plasma does contain AB against those Ag not present on its RBCs The Rh System Rh positive: Rh antigen is present on RBCs Rh negative: RBCs have no Rh antigen Blood does not normally contain anti-Rh antibodies except thru previous transfusion or pregnancy Blood Plasma 90% water, 10 % solutes Most of the solutes are proteins (formed by liver) Albumin: help maintain osmotic balance Globulins: immune mechanism Fibrinogen: blood clotting Remaining solutes are food substances, metabolic products, respiratory gases, hormones, etc Coagulation Four components critical to coagulation Prothrombin Thrombin Fibrinogen Fibrin Three stages Stage I Stage II Stage III Stage I Production of thromboplastin activator by either: Extrinsic pathway: chemicals released from damaged tissues Intrinsic pathway: chemicals present in the blood Stage II Conversion of prothrombin to thrombin by the prothrombin activator produced in stage I Stage III Conversion of fibrinogen to fibrin and production of fibrin clot by thrombin produced in Stage II Coagulation facts Many of clotting factors require calcium ion as a cofactor Liver synthesizes both prothrombin & fibrinogen. Vitamin K is necessary for production of prothrombin Conditions that oppose clotting Smooth surface of lining of blood vessels does not allow platelets to stick Antithrombins: substances in blood that oppose or inactivate thrombin Ex: Heparin Conditions that hasten clotting Rough spot in the blood vessel lining Abnormally slow blood flow Clot Dissolution Fibrinolysis: physiologic mechanism that dissolves clots Image Citations Slide 5: Hematocrit, 12/20/06, http://www.drstandley.com/labvalues_hematology.shtml Slide 13: Neutrophil, 12/27/06, http://faculty.une.edu/com/abell/histo/histolab3a.htm Slide 14: Eosinophil, 12/27/06, http://faculty.une.edu/com/abell/histo/histolab3a.htm Slide 14: eosinophil1a, 12/27/06, http://cellbio.utmb.edu/microanatomy/blood/more_eosinophils.htm Slide 15: Basophils, 12/27/06, http://faculty.une.edu/com/abell/histo/histolab3a.htm Slide 16: Medium lymphocyte, 12/27/06, http://www.anatomy.dal.ca/Human_Histology/Lab7/61LO4.html Slide 17: Monocyte, 12/27/06, http://www.meded.virginia.edu/courses/path/innes/nh/wcbmaturation.cfm Slide 21: Megakaryocyte, 12/30/06, http://www.meded.virginia.edu/courses/path/innes/nh/platelets.cfm