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PP > Introduction to Haemostasis > Flashcards

Introduction to Haemostasis Flashcards

1
Q

Define haemostasis

A

The process of blood flow slowing in response to vessel injury

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2
Q

3 components of haemostasis

A
  1. Vascular wall
  2. Platelets
  3. Coagulation cascade
    -coagulation factors
    -anticoagulant factors
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3
Q

Basic principles of normal haemostasis

A

Purpose: cessation of bleeding following trauma to BV
Process:
1. Contraction of vessel wall
2. From action of platelet plug at site
3. Formation of fibrin clot to stabilise (coagulation cascade)

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4
Q

Appearance of platelets

A

Disc shaped
Anucleate (lacking nucleus) cell fragments

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5
Q

Where do platelets derive from

A

Cytoplasm of megakaryocytes in bone marrow

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6
Q

Normal platelet count

A

150-400 ×10^9/L

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6
Q

Normal platelet count

A

150-400 ×10^9/L

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7
Q

Normal life span of platelets

A

7-10 days

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8
Q

What happened when a vessel is injured

A

Platelet Adhesion
Platelet Activation/secretion
Platelet Aggregation

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9
Q

What happens in platelet adhesion

A

Within secs.
-damage to vessel wall
-exposure of underlying tissues
-platelets adhere to collagen via vWF (von Willebrand factor) / receptor

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10
Q

What happens in platelet activation/secretion

A

-Secrete granules (dense granules) containing ADP, thromboxane etc. to become activated and activate other platelets

-involved in activation of the clotting cascade

-provide some coagulation factors by secretion from internal stores

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11
Q

What happens in platelet aggregation

A

-cross linking of platelets to form a platelet plug
-provides some stability but friable

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12
Q

6 examples of mediating factors and their roles

A
  1. Platelet receptors (binding site for fibrinogen)
  2. Von Willebrand factor (platelets adhere)
  3. Fibrinogen (links platelets)
  4. Collagen (binds platelets)
  5. ADP & Thromboxane (interaction of platelets to make plug)
  6. Thrombin (converts fibrinogen to fibrin)
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13
Q

What are the coagulation factors make in the liver

A

Fibrinogen, prothrombin
Factor 5-13
Tissue factor

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14
Q

What are the natural anticoagulants made in the liver

A

Protein C
Protein S
Antithrombin
Tissue factor pathway inhibitor

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15
Q

What are the 3 coagulation tests

A

APTT (activated partial thromboplastin time)
PT (prothrombin time)
TT (thrombin time)

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16
Q

What coagulation factors are involved in the extrinsic pathway

A

Factor VII
X, V, prothrombin, fibrinogen

16
Q

What coagulation factors are involved in the extrinsic pathway/PT

A

Factor VII
X, V, prothrombin, fibrinogen

17
Q

What factors are involved in the intrinsic pathway/ APTT

A

Factor VIII, IX, XI, XII
V, X, prothrombin, fibrinogen

18
Q

What are the 3 anti coagulation tests and diseases that can be implied from it

A

APTT (FVIII- haemophilia A, FIX-haemophilia B)
PT
Thrombin clotting time

19
Q

Deficiencies in which factors can prolong both APTT and PT

A

Factors V, X, thrombin and fibrinogen

20
Q

Goal of haemostasis

A

Make a clot
Control clotting
Break clot down

21
Q

Protein C and protein S are dependent on…

A

Vitamin K

22
Q

Describe bleeding disorders

A

-due to abnormality in the vessel wall, platelets/coagulation factors
-inherited and acquired

23
Q

Thrombocytopenia

A

-decreased production of platelets
-decreased platelet survival
-sequestration
-dilutional

24
Q

Difference between Immune and Thrombotic Thrombocytopenic purpura

A

Immune: isolated low platelet count with a normal bone marrow in absence of other causes of low platelets

Thrombotic: result of blood clots forming in small vessel throughout the body, resulting in consumption of platelets and RBC due to their breakdown

25
Q

Haemolytic-uraemia syndrome

A

Low RBC
Acute kidney injury and low platelets

26
Q

Inherited disorders of coagulation

A

Haemophilia A
Haemophilia B
Von Willebrand’s disease

27
Q

Acquired disorders of coagulation

A

Disseminated intravascular coagulation
Liver disease
Vitamin K deficiency
Anticoagulants such as Warfarin

28
Q

Symptoms of haemophilia

A

-Muscle haematomas
-Joint paint and deformity
-Prolonged bleeding post dental extraction
-Life threatening post-operative and post-traumatic bleeding
-Intracerebral haemorrhage

29
Q

Difference between haemophilia A and B

A

Both X-linked recessive
A:
-Lack of F8
-Diagnosed at early stage (prenatally/soon after birth)
-Prolonged APTT and normal PT
-Treatment with recombinant F8/DDAVP

B:
-Reduction in F9
-Prolonged APTT and normal PT
-Treatment with infusions of recombinant FIX

30
Q

Features of Von Willebrand disease

A

-Autosomal dominant
-vWF carried F8 (mediated platelet adhesion to the endothelium)

Symptoms:
-bleeding tendency is mild and foes unnoticed
-spontaneous bleeding from mucous membranes
-excessive bleeding from wounds
-menorrhagia

31
Q

Symptoms of vessel wall abnormalities

A

Easy bruising
Spontaneous bleeding from small vessels
Skin/mucous membranes

32
Q

Types of vessel wall abnormalities

A

Congenital:
HHT- Autosomal dominant
Ehlers Danilo’s

Acquired:
Senile purpura
Steroids
Infection
Scurvy

33
Q

DIC stands for

A

Disseminated intravascular coagulopathy

34
Q

What is DIC

A

Type of microangiopathic haemolytic anaemia

Blood coagulation goes into overdrive, leading to formation of microthrombi

35
Q

Causes of DIC

A

Malignancy
Massive tissue injury
Infections
Massive haemorrhage and transfusion (ABO etc)
Obstetric causes (placental abruption)

36
Q

What is Thrombophilias and its causes

A

Congenital/acquired defects of haemostasis which can increase a patient’s risk of thrombosis

Causes:
(Congenital)
Def. in natural anticoagulatnts, abnormal F5

(Acquired)
Antiphospholipid syndrome (due to antiphophlipid antibodies)

37
Q

Examples of anticoagulants

A
  1. Vitamin K inhibitors (Warfarin)
  2. Direct oral anticoagulants
  3. Low molecular weight heparins
  4. Heparin
38
Q

What are Antiplatelet drugs and its examples

A

Inhibit platelet aggregation & clot formation

E.g)
Aspirin: blocks formation of thromboxane A2 in platelets
Clopiogrel/ticagrelor: block platelet ADP

39
Q

Complications of anticoagulants

A

Bleeding

Warfarin: stop, give Vitamin K, (prothrombin complex concentrate for emergency)

Heparin stop,give protamine sulphate

PP (15 decks)

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