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Year 1: 08. CPR Exam 1 > Lecture 27: Hemostasis > Flashcards

Lecture 27: Hemostasis Flashcards

1
Q

What is another name for platelets?

A

Thrombocytes

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2
Q

From where are platelets derived?

A

Megakaryoctyes

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3
Q

What are platelets’ three simples to create a plug?

A
  1. Adhesion
  2. Activation
  3. Aggregation
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4
Q

What controls the process of platelet production?

A

Thrombopoietin: stimulates platelet production

  • If too many platelets, TPO decreases
  • If too few platelets, TPO increases
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5
Q

What produces thrombopoietin?

A

Liver

Kidney

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6
Q

Where does thrombopoietin bind?

A

c-MPL (CD-100) receptor

-found on megakaryocytes and platelets

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7
Q

What is hemostasis?

A

Preventing and stopping bleeding

-keep blood within a damaged blood vessel

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8
Q

What are the four basic steps of hemostasis?

A
  1. Vascular spasm (contraction)
  2. Formation of platelet plug
  3. Formation of blood clot
  4. Repair of damage
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9
Q

Why is vasospasm important in hemostasis?

A

Disrupts blood flow and prevent further blood loss

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10
Q

How does vasospasm occur in hemostasis?

A
  1. Myogenic contraction
  2. Platelet factors: serotonin, thromboxane A2 promote vasoconstriction
  3. Release of molecules from endothelial cells
  4. Neural reflex for spasm to occur
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11
Q

Where do platelets attach to on an injured blood vessel?

A

Negative charges on collagen and laminin

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12
Q

What specific receptors allow platelets to adhere to each other and the endothelial cells?

A

Von Willebrand Factor (vWF)

Collagen (Gp Ia/IIa)

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13
Q

What is released from dense granules in platelets when they are activated?

A

ATP and ADP
Serotonin
Calcium

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14
Q

What is released from α granules in platelets when they are activated?

A

Growth factors
Von Willebrand Factor (vWF)
Factor V
Fibrinogen

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15
Q

What factors from platelets promote aggregation?

A

ADP
Serotonin
Thromboxane A2

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16
Q

What is the role of fibrinogen?

A

When it is activated as fibrin, it helps form platelet plug

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17
Q

How does aspirin work?

A

Inhibits clotting by reducing release of thromboxane A2 from platelets

18
Q

How does Plavix (clopidogrel) work?

A

Inhibits P2Y12 receptors to prevent further platelet activation and aggregation

19
Q

What activates fibrinogen?

A

Thrombin (activated form of pro-thrombin)

20
Q

What is the role of platelet derived growth factor?

A

Stimulates fibroblasts to grow into the damaged area and differentiate into smooth muscle

21
Q

How are clots removed?

A

Plasmin: lysis fibrin and fibrinogen

22
Q

What limits clotting?

A

Fibrin: inhibits thrombin
Prostacyclin: limits platelet aggregation
Antithrombin II: anticoagulant
Heparin: anti-thrombin from mast cells

23
Q

What are some hallmarks of the extrinsic pathway?

A

Activated by external trauma and prevents blood to escape vascular system
-Factor VII

24
Q

What are some hallmarks of the intrinsic pathway?

A

Activated by internal trauma, platelets, exposed endothelium

-Factors XII, XI, IX, VIII

25
Q

What are some hallmarks of the common pathway?

A

Finish pathway of clot producition

-Factors I, II, V, X

26
Q

What factors do Vitamin K antagonists affect?

A

Factors II, VII, IX, X

-cofactor for the synthesis of these

27
Q

What do Vitamin K antagonists do?

A

Prevents blood clots

28
Q

What is the difference between primary and secondary hemostasis?

A

Primary has a weaker platelet plug

Secondary has strong plug with fibrin mesh

29
Q

What factors does thrombin activate?

A
  1. Fibrinogen –> Fibrin
  2. Factor XIII –> Factor XIIIa
  3. Factor VIII –> Factor VIIIa
  4. Factor V –> Factor Va
30
Q

What factor allows fibrin to cross link?

A

Factor XIIIa

31
Q

What are the two types of oral anticoagulants?

A

Hydroxycoumarins (Warfarin/Coumadin) and Indanediones

-Vitamin K antagonists

32
Q

What does warfarin target?

A

Vitamin K epoxide reductase

-prevents reduction of Vitamin K after its oxidized

33
Q

Which is more potent: R-Warfarin or S-Warfarin?

A

S-warfarin

34
Q

What are the roles of Protein C and S?

A

Anti-coagulants

  • inactivates Factor Va and VIIIa
  • Protein C promotes plasmin by inhibiting its inhibitor
35
Q

In Hemophilia A, what factor is deficient or absent?

A

Factor VIII

36
Q

In Hemophilia B, what factor is deficient or absent?

A

Factor IX

37
Q

What does prothrombin time (PT) evaluate?

A

Extrinsic Coagulation Pathway

  • Factors I, II, V, VII, and X
  • normal: 12-13 sec
38
Q

What does partial thromboplastin time (PTT) evaluate?

A

Intrinsic and Common Clotting Pathway

  • Factors XII, XI, IX, VIII, X, V, II, I
  • normal: 30-50 sec
39
Q

If PT is prolonged and PTT is normal, what can that mean?

A

Liver disease

-something wrong with Factor VII

40
Q

If PTT is prolonged and PT is normal, what can that mean?

A

Issue with a intrinsic pathway factor of vWF disease

41
Q

If both PT and PTT are prolonged, what can that mean?

A
  • Issue with common pathway factors
  • Warfarin overdose
  • Severe liver disease

Year 1: 08. CPR Exam 1 (29 decks)

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