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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…

22
Q

Describe bleeding disorders

A

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

23
Thrombocytopenia
-decreased production of platelets -decreased platelet survival -sequestration -dilutional
24
Difference between Immune and Thrombotic Thrombocytopenic purpura
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
Haemolytic-uraemia syndrome
Low RBC Acute kidney injury and low platelets
26
Inherited disorders of coagulation
Haemophilia A Haemophilia B Von Willebrand’s disease
27
Acquired disorders of coagulation
Disseminated intravascular coagulation Liver disease Vitamin K deficiency Anticoagulants such as Warfarin
28
Symptoms of haemophilia
-Muscle haematomas -Joint paint and deformity -Prolonged bleeding post dental extraction -Life threatening post-operative and post-traumatic bleeding -Intracerebral haemorrhage
29
Difference between haemophilia A and B
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
Features of Von Willebrand disease
-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
Symptoms of vessel wall abnormalities
Easy bruising Spontaneous bleeding from small vessels Skin/mucous membranes
32
Types of vessel wall abnormalities
Congenital: HHT- Autosomal dominant Ehlers Danilo’s Acquired: Senile purpura Steroids Infection Scurvy
33
DIC stands for
Disseminated intravascular coagulopathy
34
What is DIC
Type of microangiopathic haemolytic anaemia Blood coagulation goes into overdrive, leading to formation of microthrombi
35
Causes of DIC
Malignancy Massive tissue injury Infections Massive haemorrhage and transfusion (ABO etc) Obstetric causes (placental abruption)
36
What is Thrombophilias and its causes
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
Examples of anticoagulants
1. Vitamin K inhibitors (Warfarin) 2. Direct oral anticoagulants 3. Low molecular weight heparins 4. Heparin
38
What are Antiplatelet drugs and its examples
Inhibit platelet aggregation & clot formation E.g) Aspirin: blocks formation of thromboxane A2 in platelets Clopiogrel/ticagrelor: block platelet ADP
39
Complications of anticoagulants
Bleeding Warfarin: stop, give Vitamin K, (prothrombin complex concentrate for emergency) Heparin stop,give protamine sulphate

PP (15 decks)

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