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SIUE Clotting
Kyle's Patho Lecture
| Question | Answer |
|---|---|
| Platelets are formed | in the bone marrow from megakaryotes |
| Platelets do not have a ____ in their cytoplasm | nuclie |
| Platelets __________ when squeezing through capillaries | fragments |
| Platelet plugs function | closes small ruptures in small vessles hundreds of times daily very QUICKLY |
| Thromboxane 2 | Released by platelets. Contributes to vasopasm after tissue injury. Is a vasoconstrictor |
| Blood vessel spasm occurs primarily from | 1.) local myogenic spasm, local factors released from traumatized tissues; thromboxane 2, and nervous reflexes from pain or other sensory stimuli |
| Platelet composition (6) | 1.) Mitochondria for ATP & ADP 2.) Golgi and ER for synthesis of enzymes and storage of Calcium 3.) Contractile proteins (actin, myosin, & thrombosthenin) 4.) fibrin stabelizing factor 5.) enzymes that synthesize prostaglandins 6.) growth factors |
| Membrane of platelet consists of | surface - glycoprotein that repels adherence of platelet to normal endothelial cells Contains: phospholipids whih activate mult stages in clot cascade |
| When platelets come into contact with damaged vascular surface they? | swell, assume irregular forms releasing granuoles that contain multiple active factors, become sticky and adhere to wall, secrete ADP to form thromboxane 2 which activates aditional platelets to come to site |
| 1st mech of homeostasis for bleeding | blood vessel spasm |
| 2nd mechanism of homeostasis in bleeding | platelet plug |
| 3rd mechanism of homeostasis in bleeding | blood clot |
| Clot developement begins in _________ if trauma is severe and in _________ if trauma is minor | severe 15-20 seconds minor 1-2 minutes |
| Within ______ time after rupture vessle if opening isn't to large it is filled with a clot | 3-6 min |
| After ________ the clot retracts which | 20 min to 1 hour, and it closes the vessel further |
| Once clot has formed it can follow 2 courses | 1.) become invaded with fibroblasts (most common) 2.) or dissolve |
| Fibrin Fibers | emesh rbcs, platelets and plasma with the threads to form a clot |
| Prothrombin activator is formed via 2 ways | 1.) extrinsic pathway 2.) intrinsic pathway |
| Clotting: 3 essential steps | 1.) Damage to vessel releases complex cascade of chem reaction 2.) prothrombin activator causes prothrombin to thrombin 3.) thrombin converts fibrinogen to fibrin |
| Prothrombin is a/an | plasma protein that is unstable and can be split into 2, one is thrombin |
| Vitamin K is produced? Necessary why? | Intestines, neccessary for prothrombin formation in the liver. |
| Vitamin K is absorbed via _____ to go to liver | bile salts, so if bile ducts are obstructed, K cannot make it to the liver, therefore decreasing prothrombin formation |
| Prothrombin is formed where? | Liver. |
| Fibrinogen is a/an | plasma protein, lrg molecular size. Due to large size rarely can make it into the tissue fluids |
| Extrinsic Pathway beings with | trauma to vascular wall and tissue |
| Extrinsic Pathway | 1.) release of tissue fx: thromboplastin 2.) Activation of Factor X to Xa 3.) Factor Xa combins with Factor V to form prothrombin activator |
| Intrinsic Pathway begins with | injury to blood or exposure of blood to collagen |
| Intrinsic Pathway | 1.) Activation of XII and release of platelet factor 3 2.) XIIa activats XI 3.) XIa activates IX 4.) IXa and VII activates factor X 5.) Xa and V acctivates prothrombin activator |
| Thrombin acts as enzyme to convert | Fibrinogen to Fibrin |
| Lack of Vitamin K, in some pathological states or antiboitic use | prevents normal prothrombin formation |
| Liver dieseas such as cirrhosis causes | decreased prothrombin formation, and can depress the clotting system so much the patients tend to bleed |
| Initially when the clot is formed it is weak. Why? | Because there is no cross linking of fibrin threads at first |
| How does the clot & fibrin becomes strengthened | when trapped in the mesh, platelets release fibring stabelizing factor, which adds strength to mesh by cross linking of threads |
| Ions required for blood clotting | Calcium |
| Factors that promote clotting | 1.) prothrombin activator 2.) calcium ions 3.) vitamin K |
| How many substances are found in blood that affect coagulation | 50 |
| Factors that prevent clotting | 1.) Antithrombin III 2.) smoothness of endothelium prevents contact and activation of clot cascade 3.) thrombomodulin removes thrombin |
| Thrombomodulin does what | Prevents clotting by removing thrombin and activating protein C, which inactivates Factor V & VIII |
| Agents that remove thrombin from the blood | Fibrin threads Antithrombin III Thrombomodulin |
| The fibrin mesh absorbs what? and prevents? | Thrombin as the threads develope preventing the spread of the clots |
| Plasmin | lysis of fibrin clot and other protein coags (fibrinogen, Factors V, VII, XII, prothrombin) |
| Plasminogen to Plasmin | Plasminogen is trapped in clot when it's formed. Injured tissues slowly release T-Pa, which after the bleeding stops, converts the plasminogen in the clot to plasmin |
| Alpha Antiplasmin | Circulates in the blood, binds to plasmin and inactivates it |
| Because Plasmin is always circulating in small amounts, to be effective | Plasmin must reach certain level before with have lysis affect |
| Almost all blood clotting factors are formed in the | Liver |
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asaranita
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