PSIO 202, lecture 3 - PSIO 202 Human Anatomy and Physiology...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: PSIO 202 Human Anatomy and Physiology Lecture 3 Cardiovascular System: The Blood; White Blood Cells Objectives and Reading Assignment Reading: Tortora, pages 699-703 Lecture objectives Describe the origin and production of the various white blood cells List the characteristics and functions of red blood cells Categorize each of the white blood cell types on the basis of structure and function Describe the anatomy, physiology and relevance of phagocytosis White Blood Cells All WBCs (leukocytes) have a nucleus, but no hemoglobin Granular or agranular classification based on presence of cytoplasmic granules made visible by staining granulocytes are neutrophils, eosinophils and basophils agranulocytes are monocytes and lymphocytes Hematopoiesis-WBCs Neutrophils (Granulocyte) Polymorphonuclear Leukocytes or "Polymorphs" Nuclei = 2 to 5 lobes connected by thin strands Fine, pale lilac practically invisible granules Diameter is 10-12 microns 60 to 70% of circulating WBCs Eosinophils (Granulocyte) Nucleus with 2 or 3 lobes connected by a thin strand Large, uniform-sized granules stain orange-red with acidic dyes do not obscure the nucleus Diameter is 10 to 12 microns 2 to 4% of circulating WBCs Basophils (Granulocyte) Large, dark purple, variable-sized granules stain with basic dyes obscure the nucleus Irregular, s-shaped, bilobed nuclei Diameter is 8 to 10 microns Less than 1% of circulating WBCs Lymphocyte (Agranulocyte) Dark, oval to round nucleus Cytoplasm sky blue in color Small cells 6 - 9 microns in diameter Large cells 10 - 14 microns in diameter increase in number during viral infections 20 to 25% of circulating WBCs Monocyte (Agranulocyte) Nucleus is kidney or horse-shoe shaped Largest WBC in circulating blood does not remain in blood long before migrating to the tissues differentiates into macrophages Diameter is 12 - 20 microns Cytoplasm is a foamy blue-gray 3 to 8% of circulating WBCs WBC Physiology WBCs are less numerous than RBCs 1 WBC for every 700 RBC Leukocytosis is a high white blood cell count microbes, strenuous exercise, anesthesia or surgery Leukopenia is low white blood cell count radiation, shock or chemotherapy Only 2% of total WBC population is in circulating blood at any given time rest is in lymphatic fluid, skin, lungs, lymph nodes & spleen WBC physiology, "emigration" WBCs roll along endothelium, stick to it & squeeze between cells. adhesion molecules (selectins) help WBCs stick to endothelium They are displayed near the site of injury integrins found on neutrophils assist in movement through wall Emigration Neutrophil Function Fastest response of all WBCs to bacteria Direct actions against bacteria release lysozymes which destroy/digest bacteria release defensin proteins that act like antibiotics & poke holes in bacterial cell walls destroying them release strong oxidants (e.g., H2O2) that destroy bacteria Eosinophil Function Leaves capillaries to enter tissue fluid Releases histaminase slows down inflammation caused by basophils Attacks parasitic worms Phagocytizes antibody-antigen complexes Basophil Function Involved in inflammatory and allergic reactions Leaves capillaries & enters connective tissue as mast cells Releases heparin, histamine & serotonin Heightens the inflammatory response, increasing blood flow and often results in hypersensitivity (allergic) reactions Lymphocyte Functions B cells destroy bacteria and their toxins turn into plasma cells that produce antibodies T cells attack viruses, fungi, transplanted organs, cancer cells & some bacteria Natural killer cells attack many different microbes & some tumor cells destroy foreign invaders by direct attack Monocyte Function 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 Phagocytosis "cell eating" of bacteria Performed avidly by neutrophils and monocytes Eosinophils have weaker phagocytic activity The process involves: chemotaxis; adherence & ingestion; and destruction Chemotaxis Attraction of phagocytic cells to the site of infection Chemicals released by the pathogen and/or the infected cell attract the phagocytes Adherence Fusion of phagocyte to the pathogen's membrane Ingestion by pseudopodia, resulting in a phagosome Destruction Initiated when the phagosome fuses with a lysosome This results in a "phagolysosome" Lysozyme is released, and it destroys the membrane of the pathogen Fragments of the dead pathogen are removed from the cell by excocytosis Phagocytosis Differential WBC Count Detection of changes in numbers of circulating WBCs (percentages of each type) Normal WBC counts neutrophils 60-70% (up if bacterial infection) lymphocyte 20-25% (up if viral infection) monocytes 3 -- 8 % (up if fungal/viral infection) eosinophil 2 -- 4 % (up if parasite or allergy reaction) basophil <1% (up if allergy reaction or hypothyroid) Bone Marrow Transplant Intravenous transfer of healthy bone marrow Procedure destroy sick bone marrow with radiation & chemotherapy put sample of donor marrow into patient's vein for reseeding of bone marrow success depends on histocompatibility of donor & recipient Treatment for leukemia, sickle-cell, breast, ovarian or testicular cancer, lymphoma or aplastic anemia ...
View Full Document

Ask a homework question - tutors are online