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SH - Haematology > Composition, production and function of blood > Flashcards

Composition, production and function of blood Flashcards

1
Q

What are is blood made of (4)

A

Blood is made up of plasma (the liquid of the blood) and consists of three cellular components:
• Red blood cells which transport oxygen from the lungs to the tissues
• White blood cells which protect against infection
• Platelets which interact with blood vessels and clotting factors to maintain vascular integrity
The plasma also contains lots of clotting factors such as fibrinogen.

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2
Q

what is serum

A

Once the clotting factors are removed from the blood what is left is called serum (serum = plasma – clotting factors), which contains:
• Glucose
• Electrolytes such as sodium and potassium
• Proteins such as immunoglobulins and hormones

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3
Q

when blood is centrifuged is separates into 3 layers, what are these layers (from top to bottom) and what do they contain

A
  • Plasma:
    • Clotting or coagulation factors
    • Albumin
    • Antibodies
  • Buffy coat:
    • Platelets
    • White cells or leukocytes
  • Red blood cells
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4
Q

What is the function of blood

A
  • Transport:
    • Gases (oxygen and carbon dioxide in red cells)
    • Nutrients, waste and messages in plasma
  • Maintenance of vascular integrity:
    • Prevention of leaks (platelets and clotting factor)
    • Prevention of blockages (anticoagulants and fibrinolytics)
  • Protection from pathogens:
    • Phagocytes and killing (granulocytes/monocytes)
    • Antigen recognition and antibody formation (lymphocytes)
    • Carriage of physiologically active compounds
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5
Q

platelets develop from the myeloid progenitor cell called

A

megakaryocytes

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6
Q

what is the lifespan of RBC

A

3 months

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7
Q

what is the lifespan of platelets

A

10 days

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8
Q

name all the cells that develop from the myeloid progenitor cell myeloblast (5)

A

neutrophil, basophil, eosinophil, mast cells, macrophages

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9
Q

name the cells that originate from lymphoid stem cells

A

B and T lymphocytes

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10
Q

RBCs develop from the myeloid progenitor cell called

A

erythroblasts

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11
Q

When erythroblasts gain haemoglobin the nucleus condenses and is extruded from the cell. This cell still contains ribosomal material in the cytoplasm and is called (1). This ribosomal material is lost over 3 days and during this time and this cell is subsequently called (2) and is released into the circulation.

A
  1. a reticulocyte (immature RBC)
  2. erythrocyte
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12
Q

Substances required for this production of RBCs include

A
  • Metals: Iron, copper, cobalt, manganese
  • Vitamins: B12, folic acid, thiamine, Vit B6, C, E
  • Amino acids
  • Hormones: Erythropoietin, GM-CSF, androgens, thyroxine
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13
Q

What chains are present in haemoglobin A

A

(alpha, alpha, beta, beta) - this is adult haemoglobin

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14
Q

what chains are present in haemoglobin F

A

(alpha, alpha, gamma, gamma) is the predominant type in the foetus.

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15
Q

what binds to haemoglobin in the open deoxygenated state thereby reducing its affinity for oxygen

A

2,3 diphosphoglycerate - a product of red cell metabolism

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16
Q

increase or decrease in these 2,3, DPG, H and CO2 factors promote oxygen release

A

increase

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17
Q

when RBCs are degraded the haemoglobin moelcules is broken down to form

A

bilirubin

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18
Q

unconjugated bilirubin is transported in the plasma bound to

A

albumin

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19
Q

Once unconjugated bilirubin reaces the liver it is conjugated to

A

glucoronic acid

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20
Q

In the small bowel, conjugated bilirubin is converted to

A

stercobilinogen

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21
Q

tissue basophils are called

A

mast cells

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22
Q

tissue monocytes are called

A

macrophages

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23
Q

a high neutrophil count suggests what type of infection

A

bacterial

24
Q

a high lymphocyte count suggests what type of infection

A

viral

25
Q

define haemostasis

A

Haemostasis is the host defence mechanism that protects this integrity after injury to the vessel wall and tissue injury by blocking any holes in the vessel to limit blood loss.

26
Q

healthy vascular endothelium actively prevents haemostasis by inhibiting platelets, suppressing coagulation factors and promoting fibrinolysis. Endothelial cells achieve this by secreting various substances such as:

A

heparans, TFPI, thombomodulin, nitric oxide, prostacyclin.

27
Q

Haemostasis consists of four important steps:

A

vasoconstriction, primary haemostatic plug, stable haemostatic plug and fibrinolysis.

28
Q

Following damage to the intimal lining of the vessel the smooth muscle surrounding the vessel ______ to decrease blood loss.

A

vasoconstricts

29
Q

platelets interact with the exposed underlying endothelial matrix (namely _______).

A

collagen

30
Q

When platelets bind to collagen it releases substances, what are these

A

vWF and fibrinogen

31
Q

what is the function of vWF and fibrinogen

A

facilitate interadhesion of platelets thereby forming the platelet (primary haemostatic) plug

32
Q

name the cell surface receptors on platelets

A

ADP, epinephrin and thrombin

33
Q

Name some of the glycoprotein receptors on platelets

A

GPIa, Ib, IIb/IIIa

34
Q

what platelet receptor does vWF bind

A

GPIb

35
Q

Platelets adhere to the sub-endothelium collagen via its glycoprotein cell surface receptor

A

GPIa.

36
Q

What platelet receptor does fibrinogen bind

A

GPIIb/IIIa

37
Q

activation of the cell surface receptors on platelets causes

A

the release of arachidonic acid from the platelet membrane, which is converted by cyclooxygenase (COX) to thromboxane A2 (a powerful platelet aggregation agent).

38
Q

What does the coagulation system ultimately produce

A

fibrin strands that form a mesh around the platelets leading to a more stable haemostatic plug

39
Q

What activates the extrinsic pathway

A

factor VII interacting with tissue factor (which is released following endothelial cell damage)

40
Q

both the intrinsic and extrinsic pathway ultimately leads to the activation of factor X, what does it then go on to do

A

Factor Xa then forms a complex with factor V on the surface of activated platelets which converts prothrombin to thrombin

41
Q

What is the action of thrombin

A

conversion of fibrinogen to fibrin

Also positive feedback: factors XI, VIII, V and platelets are activated by thrombin

42
Q

what coagulation factors are deficient in haemophilia a and b

A

VIII and IX

43
Q

tissue factor pathway inactivator inhibits what parts of the clotting system

A

he TF-VIIa complex along with factor Xa is rapidly inactivated by tissue factor pathway inactivator (TFPI)

44
Q

antithrombin has inhibitory activity, principally against

A

thrombin and factor Xa.

45
Q

ProteinC - ProteinS complex inactivates

A

factor Va and VIIIa

46
Q

The fibrinolytic system is principally initiated by

A

tissue plasmin activator (tPA)

it can also be activated by urokinase

47
Q

what is the action of activated tissue plasmin activator

A

convert the circulating inactive zymogen plasminogen into the active enzyme plasmin

48
Q

what is the action of plasmin

A

hydrolyses fibrin into fibrin degradation products

49
Q

what inhibits tissue plasmin activators activity

A

plasminogen activator inhibitor (PAI)

50
Q

what inhibits plasmin activity

A

alpha 2 antiplasmin

51
Q

What drugs are inhibitors of the ADP receptors on platelets

A
  • Clopidogrel
  • Prasugrel
  • Ticagrelor
52
Q

what drugs perform GPIIb/IIIa inhibition:

A
  • Abiciximab
  • Tirofiban
  • Eptifibatide
53
Q

what drug(s) inhibit COX

A
  • Aspirin
54
Q

what is the MOA of Rivaroxiban/Edoxaban/Apixaban

A

direct factor Xa inhibitors

55
Q

what is the MOA of Dabigatran/Bivalirudin/Argatroban

A

direct thrombin inhibitors

56
Q

what is the MOA of heparins

A

increases activity of antithrombin (thereby decreasing thrombin and factor Xa)

57
Q

What is the MOA of warfarin

A

Vitamin K antagonist

SH - Haematology (6 decks)

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