2. INTRODUCTION TO PLATELETS developed by developed by Liz Fracalanza Liz Fracalanza Tina Goodyear Tina Goodyear Hugh B. Fackrell Hugh B. Fackrell Dept of Biological Sciences University of Windsor Windsor, ON Canada

3. OBJECTIVES  To examine the formed elements of blood  To define the structure and function of the cellular elements  To differentiate between the various blood cells

4. Introduction Blood may be separated into a clear fluid composed of either serum or plasma and formed elements which contain cells and cell fragments

5. Formed Elements of Blood  Thrombocytes (platelets)  Erythrocytes (red blood cells)  Leucocytes (white blood cells)

6. Prepartion of Blood  Prevent coagulation by the addition of an anticoagulant  Smear blood onto a glass slide, stain and examine under a microscope  Use an oil immersion or a high-dry objective  Use an area of the slide with little red cell overlap

7. PLATELETS

8. Platelet Characteristics  Diameter :2.9 - 4.3 um  Thickness :0.7 - 1.1 um  Cytoplasm :purple/blue-grey  Nucleus :none  Life-span :8 - 12 days  Granules :Present(not visible)

9. Platelet Function  Maintain blood vessel integrity  Prevent blood loss to maintain hemostasis  Synthesize chemical substances  provide a reaction surface for the coagulation cascade

12. Antibody - A specific immunoglobulin (protein) produced by plasma cells or B cells in response to a foreign particle. Anticoagulant - A substance that inhibits blood clotting. Basophilic - To have an affinity for basic dyes such as methylene blue used in the Wright stain.

13. Chemotaxis - A chemical stimulation causing the movement of a om the chemical source. It is a part of the inflammation response. Chromatin - The stainable material of the cell nucleus composed of basic histones, condensed nucleoprotein and parachromatin

14. Coagulation - The series of chemical reactions that result in blood clotting. Complement - Serum proteins that participate in an enzymatic cascade, resulting in a cytolytic membrane attack complex.

15. Endothelial Lining - A layer of cells that line the blood and lymphatic vessels. Hemostasis - An equilibrium of blood cells and plasma required to support life (homeostasis).

16. Heparin - An anticoagulant used to inhibit the coagulation cascade by enhancing the activity of anti- thrombin III. Histamine - A vasoactive amine secreted by the blood basophils and mast cells when stimulated by IgE antibodies. Lymphokine - A protein released by lymphocytes that acts as a cellular mediator in the immune response.