Blood • Cells in the body are fixed within tissues and must have nutrients and oxygen brought to them and waste removed. • The blood is classified as a fluid matrix connective tissue • The cells and cell fragments are the formed elements and the matrix of the blood is fluid (plasma). • Formed elements make up about 45% and plasma 55% of the total blood volume. • Blood volume: 4-5 L in females, 5-6 L in males.
Blood Functions • Distribution and transportation • Respiration • Nutritive • Excretory • Negative Aspects • Regulation and Maintenance • Hormonal regulation • Thermoregulation • pH / acid-base balance • Fluid volume • Protection • Clotting • Immunity
Major Components of the Circulatory System • Two divisions: Cardiovascular and lymphatic systems. • Cardiovascular: Heart, blood vessels • Heart • Vessels • Lymphatic: lymphatic vessels and lymphoid tissues in spleen, thymus, tonsils, and lymph nodes. • The fluid portion of the blood (plasma) passes through the capillary walls under hydrostatic pressure (interstitial fluid). • Some interstitial fluid returns to the blood and some enters the lymphatic system • Lymphatic vessels carry interstitial fluid now called lymph back to the venous blood. • Lymph nodes along the way filter and cleanse the blood before it is returned.
Erythrocytes • Structure • Biconcave, anucleate • 4.8 million/mm3 in women. • 5.4 million/mm3 in men. • 7.5 um in diameter • Components • Hemoglobin • Lipids, ATP, carbonic anhydrase • Function • Transport oxygen from lungs to tissues and carbon dioxide from tissues to lungs
Hemoglobin • Consists of: • 4 globin molecules: 2 alpha and 2 beta chains • 280 million per RBC. • Transport carbon dioxide (carbonic anhydrase involved), nitric oxide. • 4 heme molecules: Transport oxygen • Iron is required for oxygen transport
Erythropoiesis • Production of red blood cells • Stem cells proerythroblasts early erythroblasts intermediate late reticulocytes • Erythropoietin: Hormone to stimulate RBC production
Anemias • Result of either a decrease in hemoglobin / RBC or in the number of RBCs. • Symptoms: pale, lethargic, shortness of breath, tired. • Aplastic anemia: inability of red bone marrow to produce RBCs • caused by: damage to Red bone marrow, Iron of Folate deficiency • Pernicious anemia - Vitman B12 deficiency • Hemorhagic anemia - results from loss of blood • Hemolytic anemia - erythrocytes rupture or are destroyed at an increased rate. • Thalasemia - defective hemoglobin production
Malaria Sickle cell anemia
Formed Elements • Red blood cells (erythrocytes) • White blood cells (leukocytes) • Granulocytes • Neutrophils • Eosinophils • Basophils • Agranulocytes • Lymphocytes • Monocytes • Platelets (thrombocytes)
Production of Formed Elements • Hematopoiesis or hemopoiesis: Process of blood cell production • Stem cells: All formed elements derived from single population • Proerythroblasts: Develop into red blood cells • Myeloblasts: Develop into basophils, neutrophils, eosinophils • Lymphoblasts: Develop into lymphocytes • Monoblasts: Develop into monocytes • Megakaryoblasts: Develop into platelets
Neutrophil • Appearance • 2-5 lobes • 10-12 um • 54-62% of white cells • Characteristics • Fights bacterial and fungal infections • Contains peroxidases and defensins • Numbers increase with meningitis and appendicitis
Eosinophil • Appearance • Bilobed nucleus • Red granules • 11-14 um • 1-3% of white blood cells • Characteristics • Fights parasitic infections. • Releases anti-inflammatory chemicals. • Secretes enzymes that break down clots.
Basophils • Appearance • Two indistinct lobes • Blue-purple granules • 10-12 um • Less than 1% of WBC • Characteristics • Release histamine • Chemoattractant for other WBCs • Releases heparin to prevent clots. Basophil Eosinophil
Monocyte • Apearance • Nucleus round, kidney or horseshoe shaped • 12-20 um • 3-9 % of WBC • Characteristics • Transforms into macrophages
Lymphocyte • Appearance • Round nucleus • 6-14 um • 25-33% of WBC • Characteristics • Found in lymphoid tissue • Provides specific immune response • T - lymphocytes • B - lymphocytes
Hemostasis • Arrest of bleeding • Events preventing excessive blood loss • Vascular spasm: Vasoconstriction of damaged blood vessels • Platelet plug formation • Coagulation or blood clotting
Thrombocytes • Cell fragments pinched off from megakaryocytes in red bone marrow • Important in preventing blood loss • Platelet plugs • Promoting formation and contraction of clots
Coagulation • Stages • Activation of prothrombinase • Conversion of prothrombin to thrombin • Conversion of fibrinogen to fibrin • Pathways • Extrinsic • Intrinsic
Fibrinolysis • Clot dissolved by activity of plasmin, an enzyme which hydrolyzes fibrin
Blood Grouping • Determined by antigens (agglutinogens) on surface of RBCs • Antibodies (agglutinins) can bind to RBC antigens, resulting in agglutination (clumping) or hemolysis (rupture) of RBCs • Groups • ABO and Rh
Rh Blood Group • First studied in rhesus monkeys • Types • Rh positive: Have these antigens present on surface of RBCs • Rh negative: Do not have these antigens present • Hemolytic disease of the newborn (HDN) • Mother produces anti-Rh antibodies that cross placenta and cause agglutination and hemolysis of fetal RBCs
Diagnostic Blood Tests • Type and crossmatch • Complete blood count • Red blood count • Hemoglobin measurement • Hematocrit measurement • White blood count • Differential white blood count • Clotting
Erythrocytosis: RBC overabundance Anemia: Deficiency of hemoglobin Iron-deficiency Pernicious Hemorrhagic Hemolytic Sickle-cell Hemophilia Thrombocytopenia Leukemia Septicemia Malaria Infectious mononucleosis Hepatitis Blood Disorders