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BMS > Haemostasis > Flashcards

Haemostasis Flashcards

1
Q

Haemostasis

A

Process by which bleeding stops

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2
Q

Why is Haemostasis important

A

Blood is important connective tissue
Keeps all organs nourished
Important blood loss is stopped quickly as a protective mechanism.

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3
Q

Minor blood loss consequences

A

Body’s homeostatic mechanisms maintain blood volume and cells

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4
Q

Moderate blood loss consequences

A

Headache
Fatigue
Nausea
Sweating
Dizziness

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5
Q

Rapid blood loss consequences

A

Clammy, cold, pale skin
Rapid, shallow breathing
Rapid heart rate
Confusion
Weakness
Blue lips and fingers
Loss of consciousness

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6
Q

What occurs when more than 20% of blood has been lost

A

Hypovolemic shock
Usually treated in hospital
Children and elderly most vulnerable

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7
Q

Primary stages of Haemostasis

A

Vasoconstriction
Platelet plug formation

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8
Q

Secondary stages of Haemostasis

A

Coagulation

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9
Q

Stages of Haemostasis

A

Vasoconstriction
Platelet plug formation
Coagulation

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10
Q

What occurs during first stage of Haemostasis

A

Construction of blood vessels.
Platelets adhere to damaged wall.
Platelets release serotonin and thromboxane.
Smooth muscle in vessel wall contracts.

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11
Q

What occurs during second stage of Haemostasis

A

Platelets clump around exposed collagen fibres.
Protein; Von Willebrand factor stabilised platelet plug.
Platelets release ADP chemicals to attract other platelets.
Platelet plug forms.

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12
Q

Bleeding time

A

Time taken for primary haemostasis to occur
2-7 minutes normally

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13
Q

Why would bleeding time be prolonged

A

Anti platelet drugs
Anaemia
Collagen disorders; von Willebrand disease

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14
Q

What does a blood clot consist of

A

Red/white blood cells
Platelets
Fibrin

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15
Q

What occurs during coagulation

A

Complex process; results in platelet plug stabilisation by fibrin strands.
Fibrin formed by fibrinogen.

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16
Q

How is extrinsic clotting pathway activated

A

Triggered by tissue factor (III), released by damaged epithelial cells.

17
Q

How is extrinsic pathway measured

A

Prothrombin time
Normal value 11-16 seconds

18
Q

How is intrinsic clotting pathway activated

A

Triggered by blood contacting with collagen fibres in the broken wall of blood vessel.
Initiated inside blood vessel.
Activation of factor XII.

19
Q

How is intrinsic pathway measured

A

Activated partial thromboplastin time (aPTT)

20
Q

What occurs during common pathway

A

Both extrinsic and intrinsic pathways fall into common pathway.
Prothrombin is converted into thrombin.
Thrombin converts fibrinogen into fibrin.
Factor XIII acts on fibrin to form fibrin mesh.
Stabilisation of fibrin clot.

21
Q

Situations/factors which may inhibit blood clotting

A

Inherited diseases such as haemophilia A, B, C
Liver disease
Vit K deficiency
Von Willebrand disease
Anticoagulant medication

22
Q

Indications of anticoagulant medication user

A

Atrial fibrillation
Deep vein thrombosis
Stroke
(Drugs that prevent blood clotting)

23
Q

Anticoagulant medication

A

Warfarin
Rivaroxaban
Apixaban
Heparin
Dabigatran

24
Q

Summary of coagulation cascade

A
  1. Initial injury, allow blood to escape into surrounding tissue.
  2. Vasoconstriction; tissue factor (III) released and smooth muscle wall contracts.
  3. Platelet plug formation; platelets adhere to each other and form temporary seal.
  4. Coagulation; fibrinogen converts into fibrin by thrombin, stabilises and strengthens clot.
25
Q

What occurs during clot retractions

A

Contracts 90% of initial clot volume in 24hrs.
Actin and myosin pull clot tight.
Fibrin threads draw more closely.
Clot shrinkage pulls edges of damage blood vessel together.

26
Q

Fibrinolysis

A

Clot breakdown.
Plasminogen trapped within clot converts into plasmin.
Plasmin breaks down fibrin.

27
Q

Fibrinolysis is enhanced by

A

Sepsis
Severe trauma
Severe cancers
Increased consumption of fibrin with blood vessels.

28
Q

Fibrinolysis is depressed by

A

Pregnancy
Alcoholic liver disease
Chronic renal disease
Hypothyroidism

29
Q

Thrombosis

A

Formation of blood clot inside blood vessel, can block blood flow.

30
Q

What causes thrombosis

A

Over activity of coagulation
Under activity of Fibrinolysis

31
Q

Where does thrombosis often occur

A

Start at an area of vascular endothelial damage

32
Q

Haemorrhage

A

Bleeding

33
Q

How is haemorrhage controlled in dentistry

A

COMMON:
Pressure
Sutures
Packing with Haemostatic agents

UNCOMMON:
Electrosurgery
Lasters

BMS (37 decks)

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