Physiology and pathology of clotting

Question 1

What is the equation to find the haematocrit?

Answer 1

Haematocrit = Height of RBC’s / Total height

Question 2

What is the composition blood?

Answer 2

Plasma
Erythrocytes
Leukocytes
Platelets

Question 3

What is the composition of plasma ?

Answer 3

Electrolytes
Plasma proteins
Carbohydrates
Lipids

Question 4

What process are principal protein separated from plasma?

Answer 4

Electrophoresis

Question 5

What are 3 major principal proteins?

Answer 5

Albumin
Fibrinogen
Globulins

Question 6

What is the most abundant element in haemotcrit?

Answer 6

Erythrocytes

Question 7

Structure of an erythrocyte

Answer 7

Non-nucleated biconcave discs

Question 8

How is the cytoskeleton of an erythrocyte anchored to the plasma membrane?

Answer 8

Glycophorin
Band 3 Cl- HCO3 exchanger

Question 9

What are the 3 major functions of erythrocytes?

Answer 9

O2 carriage from lungs to systemic system
CO2 carriage from tissue to lungs
Buffering of acids/bases

Question 10

What are the 2 classification of white blood cells?

Answer 10

Granulocytes
Non-granular

Question 11

Role of a neutrophil?

Answer 11

Phagocytose bacteria

Question 12

Is a neutrophil a granulocyte or non-granular wbc?

Answer 12

Granulocyte

Question 13

Function of Eosinophil?

Answer 13

Combat parasites and viruses

Question 14

Is an eosinophil a granulocyte or non-granular?

Answer 14

Granulocyte

Question 15

Function of a basophil?

Answer 15

Release IL-4, histamine, heparin and peroxidase

Question 16

Is a basophil a granulocyte or non-granular?

Answer 16

Granulocyte

Question 17

Function of a lymphocyte?

Answer 17

Mature into T cells and B cells (plasma cells)

Question 18

Is a lymphocyte a granulocyte or non-granular?

Answer 18

Non granular

Question 19

What is a monocyte?

Answer 19

• Non granular wbc
  Macrophage
  Dendritic cell

Question 20

Where are platelets formed?

Answer 20

Megakaryocytes in bone marrow

Question 21

What is the feedback mechanism for platelet production?

Answer 21

Platelet receptor for TPO ->
Abundant platelets bind TPO ->
So megakaryocytes are not generated ->
Meaning no platelets are produced -?
So receptors no longer bind TPO ->
TPO stimulates megakaryocyte production ->
So platelets are produced

Question 22

Describe the composition of a platelet?

Answer 22

Nucleus free fragments -
- Mitochondria
Lysosomes
Peroxisomes
Alpha granules
Dense core granules

Question 23

What do alpha granules in platelets contain?

Answer 23

Von Willebrand factor
Clotting factor 5

Question 24

What is the external coat of a platelet covered in?

Answer 24

Platelet receptors

Question 25

Describe the structure of the inner skeleton of a platelet

Answer 25

Circumferential band of tubulin microtubules

Question 26

What is the relationship between blood flow and haematocrit?

Answer 26

Blood flow decreases with increasing haematocrit

Question 27

Describe viscosity in terms of blood flow.

Answer 27

Resistance to sliding of shearing fluid layers

Question 28

What is blood viscosity dependent on?

Answer 28

Haematocrit Fibrinogen plasma conc Vessel radius Linear velocity Temperature

Question 29

What is a concentric cylinder in terms of blood flow?

Answer 29

Different velocities of blood flowing through different layers of the blood vessel at different velocities

Question 30

What happens to velocity as you get closer to the centre of the blood vessel?

Answer 30

The velocity increases - Each concentric layer gets faster than the prior layer

Question 31

Where is concentration of rbc highest in a blood vessel?

Answer 31

In the centre

Question 32

Describe plasma skimming

Answer 32

Plasma layer around the branching vessel - Due to no rbc on the outer layer of the vessel - Lower haematocrit in this region

Question 33

How is skimming prevented?

Answer 33

Via arterial cushioning

Question 34

Describe tank treading.

Answer 34

Membrane of vessel rolls like a tank tread Helps achieve plasma spin

Question 35

What are lamina layers limited to?

Answer 35

The width of the rbc

Question 36

What happens to rbc in vessels smaller than the rbc?

Answer 36

Rbc are deformed and the viscosity falls

Question 37

When does laminar blood flow turn to turbulence?

Answer 37

When blood flow is above a critical velocity

Question 38

What happens to the parabolic profile in turbulence?

Answer 38

The parabolic profile becomes blunted

Question 39

What is local stenosis?

Answer 39

A restriction

Question 40

What combination of factors will cause turbulent flow?

Answer 40

Large radius High velocity Local stenosis

Question 41

How would you identify turbulence?

Answer 41

Produces a murmur whereas laminar is silent

Question 42

What are the 4 methods for haemostasis? (prevention of haemorrhage)

Answer 42

Vasoconstriction Increased tissue pressure Platelet plug Coagulation

Question 43

What factors are involved in vasoconstriction?

Answer 43

Thromboxane A Serotonin Thrombin Endothelin -1

Question 44

How does increasing tissue pressure prevent haemorrhage?

Answer 44

Decreases transmural pressure - Difference between intravascular pressure and tissue pressure

Question 45

What are the steps involved in a platelet plug?

Answer 45

Adhesion Activation Aggregation

Question 46

Describe platelet adhesion

Answer 46

Mediated by platelet receptors bound to ligands - Von Willebrand factor is released and binds to collagen and platelets

Question 47

What is the release of Von Willebrand factor triggered by?

Answer 47

High shear forces Cytokines Hypoxia

Question 48

What does breach of endothelium expose?

Answer 48

Collage Fibronectin Laminin

Question 49

Describe platelet activation.

Answer 49

Ligand binding leads to conformational change -> Intracellular signalling cascade -> Release reaction/exocytosis of dense storage granules or -> Cytoskeletal changes (lamellipodium and filopodia)

Question 50

Describe platelet aggregation

Answer 50

Activation leads to conformational change in the receptor -> Allowing it to bind to fibrinogen, forming molecular bridges between platelets

Question 51

What is a blood clot composed of?

Answer 51

A semisolid mass of : Erythrocytes Leukocyte Serum Mesh of fibrin

Question 52

What is thrombus?

Answer 52

An intravascular clot

Question 53

What are the 2 clotting pathways?

Answer 53

Intrinsic pathway- surface contact activation on activated platelet membrane Extrinsic pathway - membrane bound tissue factor activation, from blood contact with material from damaged cell membrane

Question 54

What do the 2 clotting pathways end in?

Answer 54

Common pathway that generates Thrombin and stable fibrin

Question 55

What are the blood clot preventions?

Answer 55

Homeostatic mechanisms Paracrine factors Anticoagulant factors

Question 56

Name 2 paracrine factors which prevent clotting

Answer 56

NO (platelet adhesion) Prostacyclin (promotes vasodilation)

Question 57

Name 2 anticoagulant factors which prevent clotting

Answer 57

Tissue factor pathway inhibitors Antithrombin

Question 58

Describe the mechanism of TFPI

Answer 58

Maintain antithrombic surface Bind and inhibit the pathway Prevent the downstream cascade when binding to a complex

Question 59

Describe the mechanism of antithrombin

Answer 59

Stops activation of various factors Modulators of clotting to prevent when no injury has occured

Question 60

What is a thrombus?

Answer 60

An intravascular blood clot

Question 61

What is venous stasis?

Answer 61

Valves of the vasculature aren't working properly

Question 62

What is hypercoaguability?

Answer 62

Coagulation at a higher rate

Question 63

When does arterial thrombosis occur?

Answer 63

Following the erosion or rupture of atherosclerotic plaque