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Pathological processes > Session 5 > Flashcards

Session 5 Flashcards

1
Q

What are the 3 major steps to hemostasis?

A
  1. Vasoconstriction
  2. Temporary blockage of a break by a platelet plug
  3. Blood coagulation, or formation of a fibrin clot which stabilises the friable platelet plug into a stable clot.
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2
Q

What is thrombosis?

A

The formatiom of a solid mass from the constituents of the blood, within the circulatory system, during life.
NOT THE SAME AS CLOTTING!

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3
Q

What is Virchow’s triad?

A

They are three fudnamental predisposing factors to thrombosis.

  1. Abnormalities of the flow of blood
  2. Abnormality of the blood vessel wall
  3. Abnormalities of the constituents of the blood
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4
Q

What is embolism?

A

Embolism is the blockage of a vessel by solid, liquid or gas at a site distant from its origin.
Over 90% of emboli are thrombo-emboli.

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5
Q

Which materials can embolise apart from a thrombus? (5)

A
  1. Air
  2. Amniotic fluid
  3. nitrogen
  4. medical equipment
  5. tumour cells
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6
Q

Which clotting factors are involved in the Extrinsic pathway?

A

7

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7
Q

Which factors are involved in the intrinsic pathway?

A

8,9,11,12

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8
Q

Which pathway does PT test?

A

extrinsic

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9
Q

Which pathway is measured by aPTT?

A

Intrinsic

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10
Q

What does PT stand for?

A

Prothrombin time

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11
Q

What is “bleeding time”?

A

How long it takes after injury for bleeding to stop. It is a measure of platelets.

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12
Q

Which tests will evaluate platelets?

A

Bleeding time

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13
Q

Do a normal PT and aPTT indicate that there is no clotting abnormality?

A

no! even if PT and aPTT are nirmal, bleeding time could still be altered as PT and aPTT don’t test platelets.

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14
Q

What ar the main clinical features of Haemophilia A?

A
  1. Sebere haemorrhage after sirgarey or trauma
  2. Spontaneous bleeding especially in joints = haemarthrosis
  3. NO petechiae normally
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15
Q

Haemophilia A is a deficiency in which factor?

A

8

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16
Q

What is the pattern of inheritance of haemophilia?

A

X-linked recessive

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17
Q

What is Christmas disease?

A

It is haemophilia B, ie. Factor 9 deficiency.

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18
Q

How is haemophilia B inherited?

A

X-linked recessive

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19
Q

Are haemophilia A and B straightforward to differentiate clinically?

A

No. Nor with very basic tward-based tests. But laboratory tests will easily tell them apart.

20
Q

Is bleeding time normal or abnormal in a factor 7 deficient patient?

A

normal! platelets arent affected it’s the PT that is affected

21
Q

Which test does heparin prolong?

A

aptt

22
Q

What is von Eillebrand disease?

A

It is a deficiency or abnormality in Von Willebrand factor.
This protein has 2 functions:
1. Assists platelet plug formation by attracting circulating platelets to site of damage.
2. Stabilises factor VIII, protecting it from premature destruction

23
Q

What is the common bleeding pattern in vWd disease?

A

mucosal bleeding reflecting the inadequate platelet function and adhesion. But patients can vary from being asymptomatic to having severe bleesing disorders.

24
Q

In vWd which tests are abnormal?

A

PT normal
aPTT prolonged as VIII no longer optimally protected
Bleeding time prolonged as platelets not optimally recruited to damage site.

25
Q

Is vWd more common than haemophilia A?

A

1/100 vWd

1/5000 haemo A

26
Q

Which macroscopic feature immediately indicates platelet abnormality?

A

Petechial rash

27
Q

What is the medical term for low platelet count?

A

thrombocytopenia

28
Q

At what platelet count is spontaneous bleeding likely to occur?

A

<30

29
Q

Where does bleedimg in association with a low platelet count usually occur?

A

Skin and mucous membranes (GIT, GUT)

Occasionally intracranial

30
Q

Why could a patient have an abnormal bleeding time yet a normal platelet count?

A

If the platelet are in sufficient amount of abnormal!

=> need platelet function test

31
Q

How can the causes of low platelet count be classified? (4)

A
  1. Decreased production
  2. Decreased survival
  3. Sequestration - in spleen (splenomegaly)
  4. Dilution: transfusion! Blood over a certain time old does not contain platelets.
32
Q

What is the difference btween a clot and a thrombus?

A

A clot happens on a cell wall and involves clotting factors.

A thrombus occurs in the lumen and involves all blood components.

33
Q

Why might decreased production of platelets occur?

A
  • illness to bone marrow: aplastic anaemia or malignancy that takes over the bone marrow
  • B12 and folate deficiencies
  • viral infections: Epstein Barr, measles, etc.
34
Q

Why might decreased platelet survival occur?

A
  1. Immune destructiom: ITP, immune thrombopenic purpura

2. Non-immune destruction

35
Q

Why might being on the aeroplane favour DVT occurance?

A
  • prolonged sitting: calf muscle pump inactive

- dehydration

36
Q

Name some risk factors for DVT.

A
  • smoking
  • obesity
  • pregnancy
  • oral contraceptives
  • dehydration
  • prolonged sitting
37
Q

Why is DVT actually most often asymptomatic?

A

Usually the thrombus will be broken up before it damages, or it is nit big enough to cause damage.

38
Q

Why are people who have had surgery, trauma or burns predisposed to DVT?

A
  1. Immobility
  2. Because in these situations, the body will produce a procoagulant factor Thromboplastin.
  3. Liver synthesis of procoagulants
  4. Decreased production of TPA
  5. Increased platelet production
39
Q

What is Trousseau’s syndrome?

A
  • thrombophlebitis associated with adenocarcinoma.
40
Q

What blood do pulmonary arteries carry?

A

deoxygenated blood

41
Q

Pulmonary embolism is most very often the consequence of…

A

DVT

42
Q

A patient with pulmonary embolism will suffer from tissue damage that will be of which colour?

A

red - collateral blood supply

43
Q

What is a saddle embolus?

A

It is an embolus at arterial BIFURCATION

44
Q

What type of necrosis is seen microscopically in ischaemic heart disease?

A

Coagulative (liquefactive in the lung)

45
Q

Which subtances are emasured to confirm MI diagnosis?

A

Troponin

46
Q

What is warfarin’s mechanism of action?

A

It is an anticoagulant as it inhibits the synthesis of Vitamin K-dependent clotting factors 2,7,9,10

47
Q

Which factors depend on VitK for synthesis?

A

2
7
9
10

Pathological processes (4 decks)

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