1. Chapter 12 Disorders of Hemostasis
Essentials of Pathophysiology
Chapter 12 Disorders of Hemostasis

2. PRE LECTURE QUIZ (TRUE/FALSE)
Platelets are also known as leukocytes.
Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder that affects the normal function and formation of platelets.
Disseminated intravascular coagulation is a condition that results in massive systemic bleeding, but coagulation function remains normal.
The use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) has been identified as a cause of impaired platelet function.
Bleeding can occur as a result of a decrease in the number of circulating platelets or because of impaired platelet function.

3. PRE LECTURE QUIZ
_________________ is the orderly, stepwise process for stopping bleeding that involves vasospasm, formation of a platelet plug, and development of a fibrin clot.
A decrease in the number of circulating platelets is known as _________________________.
Hemophilia A is an X-linked recessive disorder that involves a deficiency of factor _________________.
________________ disorders are caused by defects associated with platelets, coagulation factors, and vessel integrity.
Vitamin _______________, a fat-soluble vitamin that is continuously being synthesized by intestinal bacteria, is necessary for normal activity of factors VII, IX, and X and prothrombin.
Bleeding  K 
Hemostasis 
thrombocytopenia
VIII 

4. Seals broken blood vessels Abnormal: Inappropriate clotting
Hemostasis
Stopping blood flow
Normal:
Blood usually fluid
Seals broken blood vessels
Abnormal:
Inappropriate clotting
Insufficient clotting

5. Platelets (Thrombocytes)
Thrombopoietin
Made in liver, kidney, smooth muscle, bone marrow
Megakaryocytes formed in bone marrow
Break apart to form many platelets
Platelets live 8–9 days in circulation
Many are stored in spleen
Released when needed

6. Platelet Structure

7. Question
All but which of the following are true about platelets?
An enzyme called erythropoietin stimulates their production.
They are made from megakaryocytes.
They originate from the bone marrow.
They are stored in the spleen.

8. Answer
An enzyme called erythropoietin stimulates their production.
Rationale: Erythropoietin stimulates the production of RBCs (erythrocytes). The word literally means erythrocyte production. Platelet formation is stimulated by thrombopoietin (thrombus/clot production).

9. CLOTTING CASCADE
Author: Please add title.

10. Mediators of Hemostasis
Chemicals produced by platelets
Released at an injury to:
Start clotting by reacting with blood proteins
Help platelets stick together
Stimulate wound healing
Help platelets stick to vessel wall
Constrict blood vessels

11. Coagulation Factors
Plasma proteins
Most are synthesized by liver
von Willebrand factor made by endothelium
Circulate as inactive procoagulation factors
Calcium

12. Question
What is the effect of von Willebrand disease on the platelets?
Increased platelet aggregation
Decreased platelet aggregation
Increased platelet formation
Decreased platelet formation

13. Answer
Decreased platelet aggregation
Rationale: Von Willebrand disease is the most common hereditary bleeding disorder. It is caused by a deficiency or defect in vWF (which carries a clotting factor). The result of less clotting factor is an inability to clot.

14. Vessel Spasm

15. Cyclooxygenase Enzymes (COX) Produce Mediators of Hemostasis
Celebrex is a drug that blocks COX-2
Given to block inflamation
People taking Celebrex develop increased TXA2 levels
What problems might they have?
arachidonic
acid
COX-1
COX-2
thromboxane A 2
Prostacyclin
Macrophage Activation & Inflamation mediation
NSAIDs inhibit both COX 1 &2
COX 1 is needed for intestinal mucosa
Problems here?

16. Intrinsic and Extrinsic Pathways
Common Pathway

17. Platelets Activated platelets Platelet aggregate with fibrin threads
Non activated platelet
Platelet aggregate with fibrin threads

18. Fibrinogen  Fibrin

19. Scenario
A man had a stroke and the doctor gave him tissue plasminogen activator (TPA).
Why? What is the doctor trying to accomplish?
One of the man’s relatives wondered why they did not give him heparin or warfarin instead
What is the difference? Why might TPA be more appropriate?

20. Increased platelet number Platelet aggregation Endothelial damage
Hypercoagulability
Increased platelet number
Platelet aggregation
Endothelial damage
Increased procoagulation factors
Decreased anticoagulation factors

21. Question
True or False. Hypercoagulability states increase the risk of thrombus formation.

22. Answer
True Rationale: Hyper- as a prefix means “over” or “too much.” Coagulation/coagulability means “clotting/the ability to clot.” Hypercoagulability means “increased ability to clot or form thrombi.”

23. A woman with lupus develops breast cancer.
Scenario:
A woman with lupus develops breast cancer.
She is given radiation therapy
She begins to develop nosebleeds and bruising
Her menstrual period is abnormally heavy
Question:
Why did this happen?

24. Platelet Disorders Decreased platelet levels (thrombocytopenia)
Decreased production
Increased destruction
Platelets used up in forming clots
Impaired platelet function

25. DIC

26. Question
True or False. Platelet disorders are bleeding disorders.

27. Answer
True Rationale: Because the platelet’s job is to clot, platelet disorders mean that the platelets cannot do that job. An inability to clot results in bleeding/bleeding disorders.