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HEMATOLOGY > Haemostasis > Flashcards

Haemostasis Flashcards

1
Q

What is haemostasis?

A
  • the arrest of bleeding

- maintenance of vascular patency

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2
Q

What is needed for haemostasis?

A
  • permanent state of readiness
  • prompt response
  • localised response (don’t want blood clots happening everywhere!)
  • protection against UNWANTED thrombosis
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3
Q

What is involved in a NORMAL haemostatic system?

A
  • formation of Platelet plug = Iary haemostasis
  • formation of fibrin clot = IIary haemostasis
  • fibrinolysis—prevent complete blockage of vessel
  • anticoagulant defences
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4
Q

How are platelets formed?

A
  • in the bone marrow by BUDDING from megakaryocytes (LARGE multinucleated cells)
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5
Q

How do platelets appear?

A
  • enucleate cells

- –lasts for 7-10 dyas in the peripheral system

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6
Q

WHat occurs with endothelial damage?

A
  • exposure of collagen occurs —-signals platelet to come
  • release of VWF and other proteins with platelet receptors
  • platelet adhesion at the site
  • secretion of chemicals from the platelets > AGGREGATION of platelets
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7
Q

What does the VWF do>

A
  • helps the platelet to stick to on another anf to the collagen
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8
Q

Why platelet plug formation does not occur?

A
  • vascular (deficient COOLAGEN- in scurvy/ older people)
  • Platelets (reduced #- BM fxn is poor/ incr. destruction OR reduced fxn—-those on ASPIRIN or corticosteroids)
  • VWF
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9
Q

Consequences of FAILURE of platelet plug formation.

A
  • Bruising and purpura (seen mostly in legs)
  • Mucosal bleeding (Epistaxes/ GI/ conjunctival/ menorrhagia)
  • intracranial hemorrhages
  • retinal aemorrhages
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10
Q

Would bruising dissappear with glas pressure?

A

NO

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11
Q

How to screen for Primary haemostasis?

A
  • PLATELET COUNT

- no simple screening tests for other components

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12
Q

WHat occurs with def. pf VWF?

A
  • FACTOR viii deficiency

- IIary haemostasis problems

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13
Q

How does a fibrin clot form?

A

TF activates VII, activates V/X> activates THROMBIN (from prothrombin)> activate FIBRIN (from fibrinogen)

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14
Q

Explain the +ve feedback mechanism present to make a fibrin clot.

A

—-+ve feedback —presence of thrombin further activates VIII/Ixa> activate V/Xa even more —-more thrombin formed!

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15
Q

What is seen in single clotting factor deficiency?

A
  • deficiency of factor VIII or IX (Hemoph. B)

- —usually hereditary (HEMOPHILIA)

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16
Q

WHen may Multiple clotting factor deficiencies occur>

A
  • Acquired
  • occurs with massive TISSUE damage: cancer/ RTA/ wrong blood given
  • –(DIC)
17
Q

Name another cause of incr. fibrinolysis .

A
  • part of complex coagulopathy
18
Q

WHat occurs in fibrinolysis?

What is the main enzyme?

A
  • fibrin broken down to FDP

—–tPA needed to activate plasminogen in to PLASMIN

19
Q

How to test for EXCESS fibrinolysis in the body?

A

D-dimers test

——check for why BLOOD clots may be forming (PE/ DVT)

20
Q

What clinical pattern will you see in SINGLE clotting factors deficiency?

A

bleeding in to the JOINTs (ankle/ knee jts)

(HEMOPHILIA) —SWOLLEN

21
Q

How may DIC appear?

A
  • mass bruising (Purpura)/ INTERNAL bleeding
22
Q

How do you know if pt has def. of VII ?

A

PT will be prolonged

23
Q

How do you know if the pt has def. of VIII and IX?

A
  • APTT will be prolonged
24
Q

If PT and APTT is prolonged, what does it suggest>

A

MULTIPLE clotting factor deficiency

25
Q

What are key qs to ask the pt?

A

—-have you bled for a LONG time after a dental extraction (good 3 days)

26
Q

What to look for on P.E?

A
  • spleen palpation
  • checking muscles and joints for bleeding in hemophilia
  • general internal bleeding
27
Q

How does Heparin work?

A
  • helps anti-thrombin to the job of INHIBITING thrombin
28
Q

What does Protein C and protein S do?

A

inhibits factor V and VIII

29
Q

What occurs with thrombophilia?

A
  • def. of anticoagulants
  • –incr. tendency to develop DVT and PE
  • —seen in pts with PC/PS and anti-thrombin def.

HEMATOLOGY (20 decks)

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