Composition, production and function of blood

Question 1

What are is blood made of (4)

Answer 1

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.

Question 2

what is serum

Answer 2

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

Question 3

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

Answer 3

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

Question 4

What is the function of blood

Answer 4

• 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

Question 5

platelets develop from the myeloid progenitor cell called

Answer 5

megakaryocytes

Question 6

what is the lifespan of RBC

Answer 6

3 months

Question 7

what is the lifespan of platelets

Answer 7

10 days

Question 8

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

Answer 8

neutrophil, basophil, eosinophil, mast cells, macrophages

Question 9

name the cells that originate from lymphoid stem cells

Answer 9

B and T lymphocytes

Question 10

RBCs develop from the myeloid progenitor cell called

Answer 10

erythroblasts

Question 11

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.

Answer 11

1. a reticulocyte (immature RBC)
2. erythrocyte

Question 12

Substances required for this production of RBCs include

Answer 12

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

Question 13

What chains are present in haemoglobin A

Answer 13

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

Question 14

what chains are present in haemoglobin F

Answer 14

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

Question 15

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

Answer 15

2,3 diphosphoglycerate - a product of red cell metabolism

Question 16

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

Answer 16

increase

Question 17

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

Answer 17

bilirubin

Question 18

unconjugated bilirubin is transported in the plasma bound to

Answer 18

albumin

Question 19

Once unconjugated bilirubin reaces the liver it is conjugated to

Answer 19

glucoronic acid

Question 20

In the small bowel, conjugated bilirubin is converted to

Answer 20

stercobilinogen

Question 21

tissue basophils are called

Answer 21

mast cells

Question 22

tissue monocytes are called

Answer 22

macrophages

Question 23

a high neutrophil count suggests what type of infection

Answer 23

bacterial

Question 24

a high lymphocyte count suggests what type of infection

Answer 24

viral

Question 25

define haemostasis

Answer 25

**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.

Question 26

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:

Answer 26

**heparans, TFPI, thombomodulin, nitric oxide, prostacyclin.**

Question 27

Haemostasis consists of **four important steps:**

Answer 27

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

Question 28

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

Answer 28

**vasoconstricts**

Question 29

**platelets interact** with the **exposed** underlying endothelial matrix (namely \_\_\_\_\_\_\_).

Answer 29

**collagen**

Question 30

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

Answer 30

vWF and fibrinogen

Question 31

what is the function of vWF and fibrinogen

Answer 31

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

Question 32

name the cell surface receptors on platelets

Answer 32

ADP, epinephrin and thrombin

Question 33

Name some of the glycoprotein receptors on platelets

Answer 33

GPIa, Ib, IIb/IIIa

Question 34

what platelet receptor does vWF bind

Answer 34

GPIb

Question 35

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

Answer 35

**GPIa**.

Question 36

What platelet receptor does fibrinogen bind

Answer 36

GPIIb/IIIa

Question 37

activation of the cell surface receptors on platelets causes

Answer 37

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

Question 38

What does the coagulation system ultimately produce

Answer 38

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

Question 39

What activates the extrinsic pathway

Answer 39

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

Question 40

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

Answer 40

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

Question 41

What is the action of thrombin

Answer 41

conversion of fibrinogen to fibrin Also positive feedback: factors XI, VIII, V and platelets are activated by thrombin

Question 42

what coagulation factors are deficient in haemophilia a and b

Answer 42

VIII and IX

Question 43

tissue factor pathway inactivator inhibits what parts of the clotting system

Answer 43

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

Question 44

antithrombin has inhibitory activity, principally against

Answer 44

**thrombin** and factor **Xa**.

Question 45

ProteinC - ProteinS complex inactivates

Answer 45

factor **Va** and **VIIIa**

Question 46

The fibrinolytic system is principally initiated by

Answer 46

**tissue plasmin activator** (tPA) it can also be activated by urokinase

Question 47

what is the action of activated tissue plasmin activator

Answer 47

convert the circulating inactive zymogen **plasminogen** into the active enzyme **plasmin**

Question 48

what is the action of plasmin

Answer 48

hydrolyses **fibrin** into **fibrin degradation products**

Question 49

what inhibits tissue plasmin activators activity

Answer 49

**plasminogen activator inhibitor** (PAI)

Question 50

what inhibits plasmin activity

Answer 50

**alpha 2 antiplasmin**

Question 51

What drugs are inhibitors of the ADP receptors on platelets

Answer 51

* Clopidogrel * Prasugrel * Ticagrelor

Question 52

what drugs perform **GPIIb/IIIa inhibition**:

Answer 52

* Abiciximab * Tirofiban * Eptifibatide

Question 53

what drug(s) inhibit COX

Answer 53

* Aspirin

Question 54

what is the MOA of Rivaroxiban/Edoxaban/Apixaban

Answer 54

direct factor Xa inhibitors

Question 55

what is the MOA of Dabigatran/Bivalirudin/Argatroban

Answer 55

direct thrombin inhibitors

Question 56

what is the MOA of heparins

Answer 56

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

Question 57

What is the MOA of warfarin

Answer 57

Vitamin K antagonist