NUR 339 Exam 18
- What may clotting disorders be due to?
Answer -Issue with platelets or coagulation factors
-Hyper or hypo coagulability
- How long do platlets live in circulation?
Answer 8-9 days
- Where are many platelets stored?
Answer Spleen
- When are platelets released?
Answer When needed
- What is the function of platelets?
Answer To form platelet plug to increase clotting
- What do the platelet granules release?
Answer Mediators
- How many platelets are usually in the blood?
Answer 150,000-400,000/mL
- Are platelets thrombocytes? 1 / 4
Answer Yes
- Where are megakaryocytes formed and what do they do?
Answer Formed in the bone marrow and break apart to form many platelets.
- What does thrombopoietin control?
Answer Controls platelet production
- Where is thrombopoietin made?
Answer In the liver, kidney, smooth muscle, and bone marrow
- What is the 1st stage of normal clotting and how long does it take to occur?
Answer -Vessel spasm.
-Transient (< 1 min)
- What is a vessel spasms initiated by?
Answer Injury to blood vessel
- What is the vessel spasm due to?
Answer Hormonal (thrombaxane A2) and neural control
- What is the 2nd stage of clotting and how long does it take for it to occur?
Answer -Formation of platelet plug
-Occurs within seconds 2 / 4
- How does a platelet plug form?
- Damaged vessel leaves collagen exposed
Answer
- Von Willebrand factor is released by endothelial wall and attracts and activates platelets
- Platelets "activated" and receptors bind to Von Willebrand factor and adhere to exposed
collagen
- Chemical mediators released by platelets cause more platelet aggregation and clumping
Answer ADP, thromboxane A2 (a prostaglandin), thrombin causing nearby platelets to get sticky and clump together
- Activated platelets change shape and release chemical mediators causing more platelet
- Forms a loose platelet plug and activates the clotting cascade
aggregation
- What is the 3rd stage of clotting?
Answer Blood coagulation
- What is blood coagulation?
Answer Process by which fibrinogen converted to fibrin, which forms meshwork that holds blood cells together in clot which stabilizes clot
- What happens during blood coagulation?
Answer -Coagulation factors become ac- tivated on platelet surface and initiate clotting cascade
Answer
^2 pathways (intrinsic and extrinsic) both end with activation of Factor X leading to conversion of prothrombin to thrombin that converts fibrinogen to fibrin causing fibrin strands trap rbcs & stabilizes clot 3 / 4
- Where is the intrinsic pathway?
Answer Occurs in vascular system and is slow
- Where is the extrinsic pathway?
Answer Occurs in tissues and is fast
- Where do the intrinsic and extrinsic pathways converge?
Answer Factor 10
- Generally, how do procoagulation factors work?
Answer Factors circulating in blood
Answer activated & converted to coagulation factors in specific series of steps (cascade); one step needed to initiate next
- What do procoagulation factors promote?
Answer Clotting
- What procoagulation factor is needed in almost all steps of clotting?
Answer Cal- cium (factor 5)
- What would the effect of hypocalcemia be on clotting?
Answer Hypocoagulation
- What do anticoagulation factors do?
- / 4
Answer