医学英语 血液.ppt

BLOOD Study Guide SUMC 2011-2012 Blood composition Transport nutrients absorbed from GI tract; hormones; waste Regulate body temperature Contains ions and compounds that may be distributed to the fluid among tissues (interstitial fluid) to help maintain normal pH (7.4) Contains clotting factors Immunity (immunoglobulin) FORMED ELEMENTS Physiology of red blood cells Erythropoiesis In red bone marrow (all hematopoiesis) Hemocytoblast ? Reticulocyte (nucleated) Last stage = erythrocytes (lost nucleus) White Blood Cells Neutrophils 60% of WBCs Lobed nucleus Light staining granules Digestive enzymes Function Phagocytize destroy bacteria First cells to respond to infection Secrete antibacterial chemicals Direct actions against bacteria release lysozymes which destroy/digest bacteria release proteins that act like antibiotics poke holes in bacterial cell walls destroying them release strong oxidants (bleach-like, strong chemicals ) that destroy bacteria Eosinophils 1-4% of WBCs Lobed nucleus Eosin-staining granules Secrete anti-histamine Attack parasites lymphocytes Up to three times the diameter of an erythrocyte. Constitute about 3–8% of all leukocytes. Nucleus is kidney-shaped or U-shaped. Macrophages phagocytize bacteria, cell fragments, dead cells, and debris. Important in fighting chronic infection Take longer to get to site of infection, but arrive in larger numbers Become wandering macrophages, once they leave the capillaries Destroy microbes and clean up dead tissue following an infection Platelets (thrombocytes) Are smallest of formed elements lack nucleus Are fragments of megakaryocytes; (fragments of cytoplasm) Constitute most of mass of blood clots Release serotonin to vasoconstrict reduce blood flow to clot area Secrete growth factors to maintain integrity of blood vessel wall Survive 5-9 days, 200 000-400 000 mm3 aged and dead platelets are removed by fixed macrophages in the spleen and liver. Hematology and blood disease Blood diseases