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physiology > blood > Flashcards

blood Flashcards

1
Q

3 steps in haemostasis

A

vasocontriction
platelet plug formation
clotting cascade

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2
Q

what happens after haemostasis

A

clot retraction & fibrinolysis

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3
Q

platelet plug- how is there growth

A

positive feedback system with TXA2, ADP 5-HT

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4
Q

platelet plug- how is the growth limited

A

negative feedback with anticoagulants - antagonise platelet plug

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5
Q

describe what happens during coagulation/clotting

A

After the platelets have aggregated and bound to Von Willibrand Factor, the next step in reducing blood loss is to convert the blood around the site of damage into a plug with a solid gel like consistency
Circulating soluble plasma proteins called fibrinogen
are converted to insoluble polymer strands of fibrin
which form a mesh, trapping blood cells and preventing blood loss.

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6
Q

true or flase: Conversion of fibrinogen to fibrin is the final step in a cascade of reactions which can either follow an intrinsic pathway

A

false: Conversion of fibrinogen to fibrin is the final step in a cascade of reactions which can either follow an intrinsic OR extrinsic pathway.

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7
Q

what are most active clotting factors

A

serine protease enzymes
(hydrolyse peptide bonds)

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8
Q

what does factor XIII do

A

a transglutaminase (links glutamine and lysine residues)
knits the fibrin strands together

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9
Q

why is calcium important for blood clotting

A

no calcium would mean no clotting, important for the intrinsic cascade pathway

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10
Q

what does EDTA do

A

it is a calcium chelator and it takes calcium out of blood plasma and inhibit clotting in ‘in vitro’ storage

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11
Q

what is the cascade caused by thrimbin

A

Fibrinogen fibrin monomers
* Polymerisation, H bonds, fibrin strands
* Factor XIIIa covalent cross linkage stabilisation
* Stable mesh surrounds platelet plug
* Clot retraction

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12
Q

what surrounds the platelet plug

A

stable mesh

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13
Q

Clot Stabilisation: what is the main roles of this

A

circulating soluble fibrinogen to stable insoluble fibrin mesh

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14
Q

what is clot retraction

A

actin and mysoin filaments in platelets
contract, drawing edges of wound together (thrombin stimulates release of intracellular Ca++)

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15
Q

what is the fibrolytic system also known as

A

thrombolytic system

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16
Q

fibrolytic system: role of this system

A

clot dissolution breakdown

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17
Q

Fibrolytic systems: what is the fibrin clots catalysed by

A

Catalysed by the enzyme plasmin. Digests fibrin present in clots

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18
Q

Fibrolytic System: where is plasmin from

A

converted from plasminogen, which circulates in an inactive form

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19
Q

Fibrolytic System: which molecules ciruclate in their inactive forms

A

fibrinogen, plasminogen

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20
Q

Fibrolytic System: what is t-PA inhibited by

A

Inhibited by Plasmin Activator Inhibitor (PAI-1) – platelets rich source

21
Q

Fibrolytic System: how to increase activity of t-PA

A

Binding to fibrin increases the enzymatic activity of t-PA

22
Q

Fibrolytic System: what does t-PA stand for

A

Tissue plasminogen activator

23
Q

Fibrolytic System: where is t-PA release

A

released by endothelial cells, incorporated in clot during formation

24
Q

Fibrolytic System: where is t-PA ‘s function

A

promotes conversion of plasminogen to plasmin leading to breakdown of fibrin, fibrinogen and Factors V and VIII

25
Q

name 5 anti coagulation agents

A

prostacyclin, nitric oxide, heparin, thrombomodulin, tissue factor pathway inhibitor (TFPI)

26
Q

what are the commonly used drugs affecting haemostasis

A

aspirin, warfarin

27
Q

role of aspirin and warfarin

A

Both reduce clotting ability and therefore potentially lead to increased bleeding time

28
Q

role of Prostacyclin

A

vasodilator, antagonises TXA2

29
Q

role of Heparin

A

binds to and activates circulating plasma protein antithrombin. Neutralises clotting factors (IX-XII)

30
Q

role of Nitric oxide (NO)

A

vasodilator, opposes platelet aggregation

31
Q

role of Tissue Factor Pathway Inhibitor (TFPI)

A

binds to and inhibits thromboplastin/Factor VII complex

32
Q

role of thrombomodulin

A

binds thrombin to inhibit clotting.
Protein C + co-factor, protein S, inactivate clotting factors V and VIII and
promotes formation of plasmin from plasminogen (degrades clot)

33
Q

what does warfarin do

A

inhibits the action of vitamin K reductase, hence less conversion of
Vitamin K-2,3 epoxide to VITK-H2

34
Q

true or false: warfarin takes into action quickly

A

false: takes long time to take effect

35
Q

describe the fibrolytic system cascade

A

Dietary Vit.K –> Gamma-glutamyl carboxylase activates clotting factors II, VII, IX, X, vitamin –> Vit.K reductase reduces from K-2,3 epoxide to Vitamin K-H2

36
Q

describe the difference between activations of the intrinsic and extrinsic pathway

A

intrinsic: activated by collagen and other activators and positive feedback of thrombin
extrinsic pathway: activated through exposure of tissue factor III and positive feedback of active X

37
Q

describe the common pathway of the intrinsic and extrinsic pathway

A

prothrombin - fibrinogen - fibrin- active XIII- cross linked fibrin
positive feedback of thrombin (IP) and active x (EP)

38
Q

how much blood is there in a healthy 70 kg man, in a woman and new-born baby

A

Man: 5 litres of blood: 1L in lungs, 3L in systemic venous circulation, 1L in heart and arterial circulation
New born baby: 350ml
Less in women (approx. 7-8% body weight)

39
Q

name the 6 functions of blood

A
  1. Carriage of physiologically active compounds (plasma)
  2. Clotting (platelets)
  3. Defence (white blood cells)
  4. Carriage of gas (red blood cells)
  5. Thermoregulation
  6. Maintenance of ECF pH
    CCCDTM
40
Q

what is the composition of blood

A

Consists of plasma, red blood cells, white blood cells and platelets

41
Q

what is the composition of plasma

A

4% body weight and 95% water

42
Q

what are the 3 plasma proteins

A

albumin, globulin (subdivided into a, ß, y globulins), fibrinogens and other clotting factors

43
Q

function of plasma

A

circulates biological active molecules and compounds

44
Q

name 2 type of immune systems

A

innate vs adaptive

45
Q

innate vs adaptive immune system difference

A

INNATE
First to come into play – quick response
* Non-specific response
*no ‘memory’
ADAPTIVE
* Slower response
* Highly specific response
* Immunological memory

46
Q

describe the first exposure time to pathogens in the adaptive immune response

A

very short, shorter than innate immune system

47
Q

what is the first vs second line of defence in body

A
48
Q
A
49
Q
A

physiology (10 decks)

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