Surgery 2.2a-.csv - Name - Question - Answer.csv Flashcards
Blood coming out from area of injury
Cessation of bleeding due to several factors
If there is cut either a complete or partial transaction
There is constriction
What do lumen and plasma (blood vessels) consist of?
RBC, WBC, Platelets, Lymphocytes, Neutrophils
What cells are present in the intimal lining of blood vessels?
endothelial cells
Outer layer
medial and externa
What is goal of hemostasis?
Goal is to prevent further blood loss function of disrupted vessel that has been incised or transected
Limit blood loss from an injured vessel
What major physiological events happen (independent of each other)?
Vascular constriction, platelet plug, fibrin formation, fibrinolysis
What is the half life of platelets?
7 days/1 week
What is the normal amount of platelets?
150,000 to 400,000/uL
What are platelets?
Anuclear fragments of megakaryotes
What role do platelets play in hemostasis?
They form a hemostatic plug and contribute to thrombin formation
How do platelets adhere?
via Von Willebrand factor
What causes secretion of substances in hemostasis?
Activation of platelet in the sub endothelial cell
What might be the result of excess adhesion (platelet adhesion and fibrinogen)?
Might cause obstruction of blood vessel, causing compromise in the blood supply
What are the phases of Hemostasis?
Vascular phase (Vasoconstriction), Platelet phase (Platelets aggregate), Coagulation phase (Clot formation), and Fibrinolysis (Clot retraction, clot destruction)
What is the name of Factor I?
Fibrinogen
What is the name of Factor II?
Prothrombin
What is the name of Factor III?
Tissue Factor
What is the name of Factor IV?
Calcium
What is the name of Factor V?
Labile, Proaccelerin, Accelerator Globulin
What is the name of Factor VII?
Proconvertin, Stable Factor, Serum Prothrombin Conversion Accelerator
What is the name of Factor VIII?
Antihemophilic Factor, Antihemophilic Globulin
What is the name of Factor IX?
Christmas Factor, Plasma Thromboplastin Component
What is the name of Factor X?
Stuart – Power Factor
What is the name of Factor XI?
Plasma Thromboplastin Antecedent
What is the name of Factor XII?
Hageman Factor
What is the name of Factor XIII?
Fibrin Stabilizing Factor, Fibrinase
What are the steps of the common pathway?
Prothrombin –> Thrombin –> Fibrin
What clotting factors are involved in the intrinsic pathway?
VIII, IX, X, XI, XII
What clotting factor isinvolved in the extrinsic pathway?
VII
Vascular endothelial injury leads to what?
Platelet hemostatic function and vasoconstriction
Subendothelial collagen causes what functions in platelets?
Platelet adhesion secretion (reversible), Platelet aggregation secretion (irreversible), and Platelet aggregation
Platelet adhesion secretion involves what neurotransmitters?
ADP, serotonin, Ca2+, fibrinogen
Coagulation activation via tissue factor involves which clotting factor?
Factor VIIa
Coagulation activation via tissue factor leads to what?
Complexes on activated platelets
Complexes on activated platelets involve which clotting factors?
IXa, Xa
Complexes on activated plateletscause what?
Thrombin + Fibrinogen
Thrombin + Fibrinogen cause what?
Platelet-fibrin thrombus
What is vascular constriction?
Initial response to vessel injury
When does vascular constriction occur?
Before any platelet adherence at the site of injury
What is Thrombosane A2?
A potent constrictor of smooth muscles, it is produced locally at the site of injury via the release of arachidonic acid from the platelet membranes
What is Endothelin
A potent vasoconstrictor synthesized by injured epithelium
What is serotonin?
A potent vasoconstrictor released during platelet aggregation
What are Bradykinin and Fibrinopeptides?
Vasoconstrictors
What is the lifespan of a platelet?
7 to 10 days
What are the steps of platelet plug formation?
- Injury to intimal layer, 2. Exposes subendothelial collagen, 3. Platelets adhere, 4. Platelet adhesion, 5. Recruits other platelets from the circulating blood to seal disrupted vessel, 6. Primary Hemostasis
Activated partial thromboplastin time (aPTT)
Intrinsic pathway, common pathway…Factors: II, V, VII, IX, X, XI, XII, and Fibrinogen; High Molecular Weight (HMW) Kininogen and Prekallikrein
Prothrombin time (PT)
Extrinsic pathway, common pathway; Factors: II, V, VII, X, and Fibrinogen
Fibrin clot breakdown (lysis) allows what?
Restoration of blood flow during the healing process following injury. It begins at the same time clot formation is initiated.
If no lysis, continuous clot leads to…
occluded blood vessel –> tissue will die (e.g. heart attack, gangrene and necrosis)
Describe formation of the fibrin degradation products (FDPs), tPA (tissue plasminogen activator
Platelet –> Thrombin –> Fibrin –>FDP; Endothelium –>tPA –> Plasminogen to Plasmin to FDP
Describe the extrinsic pathway
Vascular injury –> Tissue factor + factor VII –> Tissue factor-Factor VIIa; (Tissue factor-Factor VIIa) Ca2+can lead to Factor IX (and then IXa)to Factor X (and then Xa) [or directly to Factor X and then Xa] and then Factor Va, Ca2+, Phospholipid –> Prothrombin (factor II) and Thrombin (factor IIa) –> Fibrinogen to Fibrin, Factor XIIIa, and X-linked fibrin (or Factof XIII, Ca2+, and Fibrin)
Describe the intrinsic pathway
Surface - Factor XII to Factor XIIa (inflammation, complement activation, fibrinolysis) to Physiologic to Factor XI and XIa (where it can link up to the extrinsic pathway in the Factof IX stage) or Factor VIII and VIIIa (or V) (where it can link up with the extrinsic pathway at the Factor Va and phospholipid stage) or Thrombin (factor IIa)
What is the purpose of digital pressure?
To prevent further bleeding
What is the purpose of an extremity tourniquet?
To oclude a major vessel proximal to bleeding site
What is the pringle maneuver for, and how is it performed?
For liver bleeding. It is performed with a vascular clamp, and it occludes the hepatic pedicle containing the portal vein, hepatic artery, and common bile duct (the liver is supplied by hepatic artery and portal vein)
What is a simple ligature used for?
Small vessels
How is direct pressure applied?
By “packing” a wound with gauze
How does heat achieve hemostasis?
By denaturation of protein that results in coagulation of large areas of tissue
What does electrocautery do?
Helps control the bleeding
How should the amplitude of electrocautery be set?
High enough to produce prompt coagulation, but not so high as to set up an arc between the tissue and cautery tip
How are hemostatic agents classified, and what do they do?
Classified based on their mechanism of action, and many act at specific stages in the coagulation cascade and take advantage of natural physiologic responses to bleeding
What are the qualities of an ideal topical hemostatic agent?
Significant hemostatic action, minimal tissue reactivity, non-antigenicity, in vivo biodegradability, ease of sterilization, low cost, can be tailored to specific needs
