4D 1.1 Biochem i.6 Flashcards

1
Q

Q19 drugs that work as a platelet ADP receptor antagonist are referred to as what.

A

AP drugs

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2
Q

Q41what does anti-thrombin III do

A

A plasma protein that forms an irreversible complex with thrombin

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3
Q

Q44 what are the 4 functions of thrombin

A

Converts Fibrinogen to Fibrin

Activates Factor XIII to stabilise Fibrin mesh by crosslinking

Enhances its own activation by positive feedback

Enhances platelet aggregation

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4
Q

Q26 what does A clot on top of platelet plug do

A

strengthens the plug and reinforces the seal

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5
Q

Q11 Platelets can be ACTIVATED by several factors: what are they

A
  1. ADP (adenosine diphosphate) - released by platelets, erythrocytes & endothelial cells
  2. COLLAGEN – in the connective tissue, exposed by vessel damage
  3. THROMBIN – made by enzymatic cleavage of prothrombin
  4. PAF – platelet activating factor (phospholipid) from the vessel wall & other cells
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6
Q

Q50 wound healing Occurs by 4 continuous, overlapping and precisely programmed phases

A

Rapid Haemostasis

Appropriate Inflammation

Proliferation

Tissue Remodelling

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7
Q

Q30 which factor converts prothrombin to thrombin

A

Factor X (10), Factor V (5), Ca2+, PF3

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8
Q

Q21 excessive bleeding can occur through acquired disorders such as

A

Vitamin C deficiency

Excessive exogenous (gym)

Endogenous glucocorticoids (drugs)

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9
Q

Q47 warfarin and dicoumarol are examples of

A

Vitamin k antagonists

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10
Q

Q2 Haemostasis is a complex system involving 3 major steps, what are they?

A

1 vascular spasm.

2 formation of a platelet plug.

3 blood coagulation (clotting)

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11
Q

Q32 which factor from the intrinsic pathway converts factor x (10)

A

Factor IX (9), Factor VIII (8), ca2+, PF3

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12
Q

Q4 Muscle cells contract

Constriction reduces blood flow

limits blood loss

occur during?

A

Vasoconstriction

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13
Q

Q48 anti-thrombin (synthesised in the liver), Heparin (synthesised in mast cells), protein c and s (synthesised in liver) and tissue factor pathway inhibitor, are all responsible for what

A

Preventing inappropriate clotting

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14
Q

Q36 what causes the fibrin to cross link

A

Activated factor XIII (XIIIa)

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15
Q

Q12 What are the Effects of ACTIVATION on Platelets:

A
  1. Change shape from disc to sphere with extended pseudopodia
  2. Granules release in aid of haemostasis e.g ADP, serotonin, fibronectin and vWF
  3. Aggregate
  4. Adhere to vessel wall
  5. Synthesis thromboxane
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16
Q

Q8 where are platelets derived from

A

small fragments derived from bone marrow cells called megakaryocytes

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17
Q

Q27 what is fibrin

A

insoluble, threadlike molecule, which forms a loose, mesh that traps blood cells

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18
Q

Q10 under what conditions, allow platelets to not stick to the endothelium

A

Normal

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19
Q

Q13 Outline the stages of formation for a platelet plug

A

Platelet adhesion to vessel wall -> Platelet activation -> Platelet aggregate (build Platelet mass) -> mass forms primary haemostatic plug -> plug is stabilised by fibrin.

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20
Q

Q38 protein c is activated by what

A

Thrombin

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21
Q

Q49 plasminogen is a serum protein synthesised by the liver, what is its function

A

Binds to fibrin and converts to plasmin, which slowly degrades fibrin.

Phagocytic white blood cells remove debris.

22
Q

Q45 which vitamin is essential for the synthesis of prothrombin

A

Vitamin K

23
Q

Q5 vasoconstriction is mediated by which platelet-derived products?

A

Serotonin and thromboxane

24
Q

Q34 how many peptide bonds does thrombin cleave

A

4 peptide bonds (releasing fibrinopeptides)

25
Q

Q29 what is the function of thrombin

A

catalyses conversion of fibrinogen to fibrin

activates Factor XIII

26
Q
A
27
Q

Q43. What converts prothrombin to thrombin when required?

A

BLOOD CLOTTING CASCADE

12 plasma clotting factors synthesised by the liver

some steps require Ca2+ and platelet factor 3 (PF3)

28
Q

Q24 both pathways result in the conversion of fibrinogen to

A

Fibrin – needed to stabilise blood plug

29
Q

Q35 what is the name of the cleaved product

A

Fibrin monomer

30
Q

q17 Antiplatelet drugs are used to treat arterial thrombosis, they decrease platelet aggregation and inhibit thrombus formation.

Give an example of an AP drug

A

aspirin – reduce thromboxane

31
Q

Q16 what is von Willebrand disease

A

vWD is an autosomal disease, located in chromosome 12 affecting the vWF

32
Q

Q31 which factor from the extrinsic pathway converts Factor X (10)

A

Factor VII (7), Ca2+

33
Q

q18 drugs that are platelet receptor antagonists (target GpIIb which binds vWF) are referred to as what.

A

AP drugs

34
Q

Q14 a normal/damage endothelium will produce which mediators

A
35
Q

Q7 platelets are also known as

A

Thrombocytes

36
Q

Q1 What is the definition of haemostasis

A

the stopping of a flow of blood.

37
Q

Q20 Ehlers-Danlos Syndrome is an example of

A

A congenital disorder that affects connective tissues supporting the skin, which causes excessive bleeding.

38
Q

Q25 A fibrin clot is formed by

A

interaction between the intrinsic, extrinsic and final common pathways

39
Q

Q42 what stops blood from clotting

A

Fibrinogen is always present in blood, but thrombin must not be present

Thrombin present as an inactive precursor, prothrombin

40
Q

Q39 which factors are digested by protein C

A

Factors Va and VIIIa

41
Q

Q3 Why must Haemostasis be appropriately controlled:

A

1 To avoid inappropriate clot formation.

2 Clots must be eventually degraded.

3 Clots are a temporary solution

42
Q

Q28 where is fibrin generated from

A

generated from FIBRINOGEN a large, soluble plasma protein synthesised by the liver

43
Q

Q15 what is the role of vWF and platelet receptors

A

vWF is produced by platelets and endothelial cells, which bind to Gplb and Gpllb/llla receptors of the platelets to encourage aggregation and adhesion.

44
Q

Q22 exposure of flowing blood to sub-endothelial collagen, exposed by vessel damage, activates which pathway

A

Intrinsic pathway

45
Q

Q6 Example of vasodilators and inhibitors of platelet aggregation are?

A

Prostacyclin and nitric oxide

46
Q

Q33 how many polypeptide chains does fibrinogen consists of

A

Fibrinogen consists of 6 polypeptide chains

47
Q

Q9 what allows the megakaryocyte to contract

A

High levels of actin and myosin

48
Q

Q23 exposure of flowing blood to a protein called tissue factor (TF) through tissue damage, activates which pathway

A

Extrinsic pathway

49
Q

Q46 what is the role of Ca2+

A

Anchors prothrombin to platelet membrane surface after injury

Brings prothrombin near clotting factors (Xa and Va)

50
Q

Q37 clotting factors are labile, what is responsible for the removal of clotting factors

A

Dilution of blood flow, liver and degradation of proteases

51
Q

Q40 thrombin has dual function, what does this mean

A

Catalyses formation of fibrin

Initiates the deactivation of the clotting cascade