Blood BSMED 2-1 Functions • Transport gases, nutrients, waste products • Regulates pH, fluid and ion balance • Temperature regulation • Protection • Blood clotting prevents fluid and cell loss • Tissue repair Composition • Connective tissue consisting of plasma and formed elements • 5 liters = total blood volume Plasma 91% water and 9% suspended and dissolved substances Plasma proteins - 7% albumin, globulin, fibrinogen Plasma solutes - 2% ions, nutrients, waste products, gases, enzymes, hormones Maintains osmotic pressure Immunity Prevents blood loss Transport molecules Formed Elements Cells • Red Blood Cells • White Blood Cells Cell fragments • platelets Hematopoiesis • production of formed elements in the red bone marrow by stem cells • RBC (erythrocytes) • WBC (leukocytes) • Platelets (thrombocytes) RBC • Biconcave disk-shaped cells • No nucleus • Carbonic anhydrase – carbon dioxide transport • Contain hemoglobin – heme - binds O2 – globin - binds CO2 • Erythropoietin – produced by kidneys in response to low oxygen levels; stimulates rbc production in the bone marrow • Worn-out rbcs’ are phagocytized by macrophages in the spleen and liver • Hgb is broken down, iron and amino acids are reused, heme is converted into bilirubin and is secreted in bile WBC • Granular – neutrophils • phagocytize foreign substances – eosinophils • produce antihistamines – basophils • produce heparin, histamine, seratonin • Agranular – monocytes • phagocytize bacteria and cellular debris • macrophages - in tissues – lymphocytes • T lymphocytes • B lymphocytes Platelets • Cell fragments that prevent blood loss • NV = 140,000 – 400,000 Preventing Blood Loss • Vascular spasm – constrict to prevent blood flow • Platelet Plugs • Blood clotting The Clotting Mechanism Ruptured blood vessel attracts Thrombocytes ¯ Damaged tissue releases Thromboplastin ¯ Thromboplastin + Ca+, ions, and proteins® Prothrombin activator + Ca+ ® Prothrombin ® Thrombin ® Fibrinogen ® Fibrin • Thrombosis - unwanted clotting • Embolus - circulating blood clot • Infarction – tissues killed as a result of loss of blood supply • Anticoagulants – prevents clot formation • Antithrombin • heparin
Posted on: Tue, 30 Jul 2013 10:34:56 +0000
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