L9 - Hemostasis and blood types

• What is hemostasis?

  Process of preventing blood loss
• What are the three steps of hemostasis?

  1. Vascular spasm
  2. Platelet plug formation
  3. Coagulation (blood clotting)
• What occurs during vascular spasm?

  Smooth muscle contracts, causing vasoconstriction
• What is the role of platelets in hemostasis?

  They form a sticky plug at injury sites
• What triggers platelet adhesion during hemostasis?

  Exposure of collagen fibers in damaged vessels
• What antigens are present in type A+ blood?

  A and D antigens
• What antibodies are present in type A+ blood?

  anti-B antibodies
• What is the function of fibrin in blood clotting?

  Forms a mesh that traps blood cells
• Who can receive blood from an A+ donor?

  A+, AB+
• What are the phases of blood clotting?

  1. Formation of prothrombin activator
  2. Common pathway to thrombin
  3. Common pathway to fibrin mesh
• Who can donate blood to an A+ recipient?

  A+, A−, O+, O−
• What is the intrinsic pathway in coagulation?

  Triggered by damage to endothelium within a vessel
• What antigens are present in type A− blood?

  A antigen
• What antibodies are present in type A− blood?

  anti-B, anti-D antibodies
• Who can receive blood from an A− donor?

  A+, A−, AB+, AB−
• What is the extrinsic pathway in coagulation?

  Triggered by tissue factor released from damaged cells
• Who can donate blood to an A− recipient?

  A−, O−
• What antigens are present in type B+ blood?

  B and D antigens
• What antibodies are present in type B+ blood?

  anti-A antibodies
• Who can receive blood from a B+ donor?

  B+, AB+
• Who can donate blood to a B+ recipient?

  B+, B−, O+, O−
• What antigens are present in type B− blood?

  B antigen
• What antibodies are present in type B− blood?

  anti-A, anti-D antibodies
• What is the role of thrombin in coagulation?

  Converts fibrinogen to fibrin
• Who can receive blood from a B− donor?

  B−, AB−
• What is clot retraction?

  Stabilizes clot and draws vessel edges together
• What is fibrinolysis?

  Process of removing unneeded clots
• What are thromboembolic disorders?

  • Thrombus: clot in unbroken vessel
  • Embolus: thrombus that breaks away
  • Embolism: obstruction of a vessel by embolus
• Who can donate blood to a B− recipient?

  B−, O−
• What are bleeding disorders?

  • Thrombocytopenia: low platelet count
  • Impaired liver function: affects clotting factor synthesis
  • Hemophilia: deficiency in specific clotting factors
• What determines blood groups?

  Presence of specific antigens on RBCs
• What are the four blood types in the ABO system?

  A, B, AB, O
• What is the role of antibodies in blood types?

  They bind to foreign antigens in blood
• What is the significance of type O blood?

  Universal donor with no antigens present
• What is the significance of type AB blood?

  Universal recipient with no anti-A or anti-B antibodies
• What happens during a transfusion reaction?

  Recipient antibodies react with donor antigens
• What is the Rh factor?

  Group of RBC antigens that can be present or absent
• What can happen if an Rh- mother has an Rh+ child?

  Mother may produce anti-D antibodies in subsequent pregnancies
• What is blood typing?

  • Determination of possible transfusion reactions
  • Ensures compatibility between donor and recipient blood types
• Can patient 1 donate blood to patient 2 if patient 1 has A blood type?

  No, patient 1 has A antibodies