4D 1.1 Biochem i.6 Flashcards
Q19 drugs that work as a platelet ADP receptor antagonist are referred to as what.
AP drugs
Q41what does anti-thrombin III do
A plasma protein that forms an irreversible complex with thrombin
Q44 what are the 4 functions of thrombin
Converts Fibrinogen to Fibrin
Activates Factor XIII to stabilise Fibrin mesh by crosslinking
Enhances its own activation by positive feedback
Enhances platelet aggregation

Q26 what does A clot on top of platelet plug do
strengthens the plug and reinforces the seal
Q11 Platelets can be ACTIVATED by several factors: what are they
- ADP (adenosine diphosphate) - released by platelets, erythrocytes & endothelial cells
- COLLAGEN – in the connective tissue, exposed by vessel damage
- THROMBIN – made by enzymatic cleavage of prothrombin
- PAF – platelet activating factor (phospholipid) from the vessel wall & other cells
Q50 wound healing Occurs by 4 continuous, overlapping and precisely programmed phases
Rapid Haemostasis
Appropriate Inflammation
Proliferation
Tissue Remodelling
Q30 which factor converts prothrombin to thrombin
Factor X (10), Factor V (5), Ca2+, PF3
Q21 excessive bleeding can occur through acquired disorders such as
Vitamin C deficiency
Excessive exogenous (gym)
Endogenous glucocorticoids (drugs)
Q47 warfarin and dicoumarol are examples of
Vitamin k antagonists
Q2 Haemostasis is a complex system involving 3 major steps, what are they?
1 vascular spasm.
2 formation of a platelet plug.
3 blood coagulation (clotting)
Q32 which factor from the intrinsic pathway converts factor x (10)
Factor IX (9), Factor VIII (8), ca2+, PF3
Q4 Muscle cells contract
Constriction reduces blood flow
limits blood loss
occur during?
Vasoconstriction
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
Preventing inappropriate clotting
Q36 what causes the fibrin to cross link
Activated factor XIII (XIIIa)
Q12 What are the Effects of ACTIVATION on Platelets:
- Change shape from disc to sphere with extended pseudopodia
- Granules release in aid of haemostasis e.g ADP, serotonin, fibronectin and vWF
- Aggregate
- Adhere to vessel wall
- Synthesis thromboxane
Q8 where are platelets derived from
small fragments derived from bone marrow cells called megakaryocytes
Q27 what is fibrin
insoluble, threadlike molecule, which forms a loose, mesh that traps blood cells

Q10 under what conditions, allow platelets to not stick to the endothelium
Normal
Q13 Outline the stages of formation for a platelet plug
Platelet adhesion to vessel wall -> Platelet activation -> Platelet aggregate (build Platelet mass) -> mass forms primary haemostatic plug -> plug is stabilised by fibrin.
Q38 protein c is activated by what
Thrombin
Q49 plasminogen is a serum protein synthesised by the liver, what is its function
Binds to fibrin and converts to plasmin, which slowly degrades fibrin.
Phagocytic white blood cells remove debris.
Q45 which vitamin is essential for the synthesis of prothrombin
Vitamin K
Q5 vasoconstriction is mediated by which platelet-derived products?
Serotonin and thromboxane
Q34 how many peptide bonds does thrombin cleave
4 peptide bonds (releasing fibrinopeptides)
Q29 what is the function of thrombin
catalyses conversion of fibrinogen to fibrin
activates Factor XIII

Q43. What converts prothrombin to thrombin when required?
BLOOD CLOTTING CASCADE
12 plasma clotting factors synthesised by the liver
some steps require Ca2+ and platelet factor 3 (PF3)
Q24 both pathways result in the conversion of fibrinogen to
Fibrin – needed to stabilise blood plug
Q35 what is the name of the cleaved product
Fibrin monomer
q17 Antiplatelet drugs are used to treat arterial thrombosis, they decrease platelet aggregation and inhibit thrombus formation.
Give an example of an AP drug
aspirin – reduce thromboxane
Q16 what is von Willebrand disease
vWD is an autosomal disease, located in chromosome 12 affecting the vWF

Q31 which factor from the extrinsic pathway converts Factor X (10)
Factor VII (7), Ca2+
q18 drugs that are platelet receptor antagonists (target GpIIb which binds vWF) are referred to as what.
AP drugs
Q14 a normal/damage endothelium will produce which mediators

Q7 platelets are also known as
Thrombocytes
Q1 What is the definition of haemostasis
the stopping of a flow of blood.
Q20 Ehlers-Danlos Syndrome is an example of
A congenital disorder that affects connective tissues supporting the skin, which causes excessive bleeding.
Q25 A fibrin clot is formed by
interaction between the intrinsic, extrinsic and final common pathways
Q42 what stops blood from clotting
Fibrinogen is always present in blood, but thrombin must not be present
Thrombin present as an inactive precursor, prothrombin
Q39 which factors are digested by protein C
Factors Va and VIIIa
Q3 Why must Haemostasis be appropriately controlled:
1 To avoid inappropriate clot formation.
2 Clots must be eventually degraded.
3 Clots are a temporary solution
Q28 where is fibrin generated from
generated from FIBRINOGEN a large, soluble plasma protein synthesised by the liver

Q15 what is the role of vWF and platelet receptors
vWF is produced by platelets and endothelial cells, which bind to Gplb and Gpllb/llla receptors of the platelets to encourage aggregation and adhesion.

Q22 exposure of flowing blood to sub-endothelial collagen, exposed by vessel damage, activates which pathway
Intrinsic pathway
Q6 Example of vasodilators and inhibitors of platelet aggregation are?
Prostacyclin and nitric oxide
Q33 how many polypeptide chains does fibrinogen consists of
Fibrinogen consists of 6 polypeptide chains
Q9 what allows the megakaryocyte to contract
High levels of actin and myosin
Q23 exposure of flowing blood to a protein called tissue factor (TF) through tissue damage, activates which pathway
Extrinsic pathway
Q46 what is the role of Ca2+
Anchors prothrombin to platelet membrane surface after injury
Brings prothrombin near clotting factors (Xa and Va)
Q37 clotting factors are labile, what is responsible for the removal of clotting factors
Dilution of blood flow, liver and degradation of proteases
Q40 thrombin has dual function, what does this mean
Catalyses formation of fibrin
Initiates the deactivation of the clotting cascade