Lymphocytes are spherical white blood cells that make up 20-45% of circulating white blood cells. They have a dark staining nucleus and thin rim of blue staining cytoplasm. Each lymphocyte recognizes a specific antigen. T lymphocytes can directly attack foreign cells, while B lymphocytes transform into plasma cells that secrete antibodies. Hemostasis is the prevention of blood loss achieved through vascular constriction, formation of a platelet plug, and formation of a blood clot. When a blood vessel is cut, the smooth muscle contracts to reduce blood flow. Platelets aggregate at the site of injury to form a platelet plug. Blood coagulation involves the conversion of prothrombin to thrombin by prothrombin activ

1. Lymphocytes Agranulocyte 20-45% of WBCs Spherical, dark-staining nucleus Thin rim of blue staining cytoplasm Each lymphocyte recognizes and acts against a specific antigen

2. Lymphocytes T lymphocytes can attack foreign cells directly (17.6)

3. Lymphocytes B lymphocytes transform into plasma cells and secrete antibodies

4. Hemostasis means prevention of blood loss and this achieved by: Vascular constriction Formation of a platelet plug Formation of blood clot Growth of fibrous tissue into the blood clot Hemostasis

5. After blood vessel has been cut, the smooth muscle wall contract; this immediately reduces the flow of blood from the ruptured vessel Vascular Constriction

6. Platelets or thrombocytes Formed in the bone marrow from megakaryocytes Do not have nuclei Function in the clotting process. Normal value – 150,000 to 300,000/cubic millimeter. It has a half life in the blood of 8 – 12 days, its functional process run out over several weeks Formation of platelet plug

7. Formed by fragmentation from megakaryoctyes

8. Contractile protein thrombosthenin that can cause the platelet to contract Endoplasmic reticulum that store Calcium ions Mitochondria capable of forming ATP Enzymes that can synthesize prostaglandins which involves in local tissue reactions Contain fibrin stabilizing factor Growth factors that causes vascular cells to grow and multiply Platelet functional characteristics

9. Platelet begin to swell and assume irregular forms when comes in contact with collagen fibers They become sticky so that they adhere to collagen in the tissue They secrete ADP and form thromboxane which activate nearby platelets The damaged vascular wall activates increasing numbers of platelets thus forming platelet plug. (In small vessels the platelet plug is all that is necessary to stop the bleeding). Mechanism of platelet plug

10. Platelet Plug Formation Exposed collagen binds and activate platelets Release of platelet factors Attract more platelets Aggregate into platelet plug

11. Blood coagulation take place in three steps As result of rupture blood vessels, formation of prothrombin activator (protein manufacture in the liver) Conversion of prothrombin to thrombin in the presence of calcium The thrombin acts as enzyme to convert fibrinogen (blood protein) into fibrin fibers that enmesh platelet, blood cells and plasma to form clot Note: vitamin K is required by liver for formation of prothrombin Blood coagulation in the ruptured vessel

12. Prothrombin Prothrombin Ca Activator Thrombin Fibrinogen Fibrinogen monomer Ca Fibrin fibers Activated fibrin Stabilizing factor Cross linked fibrin fibers Blood Coagulation

13. SEM of a clot with platelet, fibrin mesh, rbc’s The clot composed of meshwork of fibrin fibers entrapping blood cells, platelets and plasma

14. Overview of Hemostasis: Clot Formation & Vessel Repair

15. Prothrombin activator is generally formed in two ways Extrinsic pathway (begins with trauma to the vascular wall) Intrinsic pathway (begin with the blood) Initiation of coagulation

16. Pathways for initiating clotting

17. Preventing blood clotting in vascular system is Smoothness of the endothelial cell surface Layer of glycocalyx on the endothelium Protein bound with the endothelial membrane thrombomodulin which binds thrombin Prevention of blood clotting in the vascular system

18. The most important anticoagulant in the blood Fibrin fibers Antithrombin III or antithrombin-heparin cofactor Both fibrin fibers and antithrombin acts as antithrombin About 85-90% of thrombin becomes adsorbed to the fibrin fibers The thrombin that does not adsorb combines with antithrombin III which block the effect of thrombin Antithrombin action of fibrin and antithrombin III

19. Heparin is anticoagulant, low concentration in the blood Effectiveness of antithrombin III increases when it combines with heparin Heparin is formed by basophilic and mast cell Heparin

20. Plasma protein contain euglobulin called plasminogen when activated becomes plasmin Plasmin resemble trypsin Plasmin digest fibrin fibers and other protein coagulants Plasmin caused lysis of a clot Fibrinolysis of blood clot - plasmin

21. Injured tissue release activator called tissue plasminogen activator (t-PA) which convert plasminogen to plasmin Activation of plasminogen

22. Dissolving the clot

23. A comparison of RBCs, WBCs and Platelets

24. A comparison of RBCs, WBCs and Platelets

25. Albumin Helps control osmotic pressure Helps control diffusion of water Globulin Includes antibodies (Abs) Transport proteins (lipids, iron, copper, etc.) Fibrinogen Involved in clotting Plasma proteins

26. All the albumin and fibrinogen and 50 – 80% of globulin are formed in the liver The reminder of the globulin are formed in the lymphoid tissues Formation of the plasma proteins

27. Normal values Total protein: 4.2 - 5.6 g/dl Albumin: 2.3 - 3.5 g/dl Globulin: 1.9 – 2.1 g/dl

29. Regulation of colloidal pressure

30. ALBUMIN Functions of albumin Maintenance of the osmotic pressure of plasma Transport of free fatty acids

32. Some globulins are made by the liver, while others are made by the immune system.

33. Other globulins transport metals, such as iron, in the blood and help fight infection.