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Block 2 Pathophysiology > Hematology- hemostasis > Flashcards

Hematology- hemostasis Flashcards

1
Q

The processes which
Allow blood to remain fluid in vessels
Form a hemostatic plug at sites of vascular injury

A

Hemostasis

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2
Q

___when the thrombus forms at one place and travels to a distant site

A

Embolus

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3
Q

____ at the site of intravascular coagulation

A

Thrombus

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4
Q

Hematoma,Purpura, Ecchymoses,Petechiae are examples of ____

A

Bruising: bleeding into or beneath the skin

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5
Q

Signs and symptoms of defective hemostasis

A

Bruising: bleeding into or beneath the skin
Mucosal bleeding
Menorrhagia: heavy, prolonged menstrual bleeding at regular intervals

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6
Q

_____ is heavy, prolonged menstrual bleeding at regular intervals

A

Menorrhagia

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7
Q

types of Mucosal bleeding

A

Epistaxis: “nose bleed”
Hematemesis: vomiting blood
Hemoptysis: coughing up blood
Hemarthrosis: bleeding into joint capsules

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8
Q

______is normally antithrombotic

A

Endothelium

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9
Q

Endothelial factors with antiplatelet actions

A

Prostacyclin (PGI2)
Nitric oxide (NO)
Adenosine diphosphatase

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10
Q

Endothelial factors with anticoagulant actions

A

Heparin-like molecules work with antithrombin III (liver) to inactivate thrombin, factor Xa and others

Thrombomodulin converts thrombin from procoagulant to anticoagulant

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11
Q

_____ work with antithrombin III (liver) to inactivate thrombin, factor Xa and others

A

Heparin-like molecules

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12
Q

_______ converts thrombin from procoagulant to anticoagulant

A

Thrombomodulin

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13
Q

Endothelial factors with fibrinolytic actions

A

Tissue plasminogen activator (tPA)

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14
Q

Endothelial injury (activation) favors ____

A

thrombosis

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15
Q

Endothelial factors with pro-platelet aggregation actions

A

Von Willebrand factor (vWF)

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16
Q

this is Cofactor for platelet binding to collagen

Produced by activated endothelial cells

A

Von Willebrand factor (vWF)

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17
Q

Endothelial factors with pro-coagulation actions

A

Tissue factor

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18
Q

this is Produced in response to cytokines and endotoxin

Activates the extrinsic clotting cascade

A

Tissue factor

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19
Q

Endothelial factors with pro-fibrin activation

A

Inhibitors of plasminogen activator (PAI)

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20
Q

this Inhibit fibrinolysis

A

Inhibitors of plasminogen activator (PAI)

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21
Q

Bleeding Disorders May be caused by failures in

____

A

Primary hemostasis–>Platelet deficiency or dysfunction

Secondary hemostasis–>Dysfunction in the coagulation system

Combination

22
Q

Primary Hemostasis: Platelets

A 
Form platelet plug in porous vessels
Activate blood coagulation (secondary hemostasis)
Support endothelium
Secrete cytokines
Lifespan 5-10 days
Removed by spleen 
    and liver
23
Q

Platelets: exposure to ADP, collagen, thrombin favors activation and results in the following

A
  1. Adherence to collagen and activation by von Willebrand factor (vWF)
  2. Shape change to increase clumping- Exposes phospholipid complexes which activate the intrinsic coagulation pathway (secondary hemostasis)
  3. Secrete pro-aggregatory granule products (e.g., ADP) and thromboxane A2 (TXA2)
  4. Activate (recruit) other platelets
  5. Produce primary hemostatic plug
24
Q

Primary Hemostasis: Platelet Adhesion

Step 1: Adherence

A 
Activated (injured) endothelial cells secrete von Willebrand factor (vWF)
When basement membrane 
   collagen is exposed, vWF 
   binds to collagen and 
   platelets bind to vWF 
   (platelet Gp1b and Gp2b3a 
   receptors), forming plug
25
Primary Hemostasis: Platelet Shape | Step 2: Activation and shape change
The first step in platelet activation results in shape change in two steps - Calcium influx activates cleavage of actin filaments, causing the cell to become spherical - Actin reassembles in linear form making spicules - Calcium influx also activates phospholipases, modifying membrane phospholipids (secondary hemostasis) Shape change promotes platelet aggregatio
26
Primary Hemostasis: Granule Release | Step 3: Degranulation
Initiated by calcium influx which causes shape change - Delta granules contain ADP, calcium, serotonin, epinephrine ADP and calcium supports recruitment of more platelets Serotonin and epinephrine results in vascular constriction - Lambda and Alpha granules contain lytic enzymes, growth factors, etc. - Pro-thrombotic thromboxane (TXA2) produced from membrane phospholipids - Healthy endothelial cells secrete anti-thrombotic prostacyclin (PGI2), blocks platelet degranulation
27
Primary Hemostasis: Platelet Recruitment | Step 4: Recruitment of more platelets
ADP (from delta granules) and TXA2 (membrane phospholipid metabolism) enlist more platelets to undergo the same processes, perpetuating platelet aggregation
28
Platelet adhesion to collagen is mediated by endothelial cell _________.
von Willebrand factor
29
Platelet aggregation results in release of ADP (enhances aggregation) and phospholipid complex (initiates intrinsic clotting pathway), resulting in _________.
fibrin deposition
30
Together the aggregated platelets and fibrin form a ______.
hemostatic plug
31
______ defined as platelet count below 150,000 platelets/μL (normal range, 150,000/μL to 400,000/μL)
Thrombocytopenia
32
Spontaneous bleeding rarely occurs until platelet counts fall below _____
20,000 platelets/μL
33
Platelet counts from 20,000 to 50,000 platelets/μL can aggravate _____
post-traumatic bleeding
34
Bleeding episodes usually involve small vessels in ________(petechiae, purpura), risk of intracranial bleeding
skin and mucous membranes
35
Bleeding resulting from ______ is associated with a normal PT and PTT (measures of secondary hemostasis)
thrombocytopenia
36
Platelet Disorders: Thrombocytopenia | Four primary causes
Decreased platelet production Sequestration Dilution Decreased platelet survival
37
Decreased platelet production
Depressed marrow output (e.g., aplastic anemia and leukemia) Certain drugs and alcohol, HIV, myelodysplastic syndromes
38
Sequestration
The spleen normally sequesters 30% to 35% of the body's platelets, but this can rise to 80% to 90% with splenomegaly, producing moderate degrees of thrombocytopenia
39
Dilution
Massive transfusions with platelet-poor plasma, packed RBC, or crystalloid fluids can produce a dilutional thrombocytopenia
40
Decreased platelet survival
Immune thrombocytopenia caused by auto- or allo-antibodies to platelets Nonimmune thrombocytopenia caused by uncontrolled, systemic platelet activation or destruction
41
Functional disorders of platelets | hereditary
Adhesion defects Aggregation defects Release defects
42
Functional disorders of platelets | Iatrogenic disorders
``` ADP receptor inhibitors Gp2b3a antagonists Phosphodiesterase inhibitors Thrombin receptor blockers Cyclooxygenase / thromboxane inhibitors Adenosine reuptake inhibitors ```
43
Most common inherited bleeding disorder in humans (1% population)
Von Willebrand’s Disease
44
Majority of Von Willebrand’s Disease cases are ______. | May be acquired or associated with other conditions (malignancy, immunologic responses, drugs, miscellaneous disorders)
autosomal dominant
45
Von Willebrand’s Disease presentation
Symptomatic at any age Epistaxis in childhood Easily bruised especially with sports Excessive bleeding with surgical procedures Heavy menstrual (menorrhagia) and peripartum bleeding May be history of bleeding after use of ASA or NSAIDS
46
what is Antiphospholipid syndrome (autoimmune)
Aggregation defect where antiphospholipid autoantibodies result in platelet coagulation
47
what is Antiphospholipid syndrome (autoimmune) is Associated with
Associated with Recurrent arterial and venous thrombosis (50%) Repeated fetal loss Thrombocytopenia
48
Secondary hemostasis is associated with _____ and their activation
clotting factors
49
____is a required cofactor for prothrombin
Vitamin K
50
___ is principal initiator of intrinsic pathway
Collagen
51
Secondary Hemostasis Process accelerated by
Factor VIIa (extrinsic pathway ) Thrombin (common pathway) Activated platelet membrane phospholipids (primary hemostasis)
52
Secondary Hemostasis Process intrinsic pathway ends in
Ends in activation of factor X to factor Xa

Block 2 Pathophysiology (8 decks)

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