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L4 Red and White Blood Circulation
Cellular mechanical factors affecting deformation and circulation
1
...
They have a higher volume
 Surface area/volume ratio:  ability to adapt shape (either need to increase area or decrease volume
therefore need to have excess membrane to adapt the shape)
2
...
CYTOPLASM
 Viscosity (e
...
, haemoglobin concentration in RBC)
 WBC – Cytoskeleton (actin scaffolding, rearranged during migration – dominant factor for WBC),
inclusions, organelles, nucleus is quite rigid
...
Pathological
Controlled vs
...
RBCs
 Don’t normally adhere to vessel wall
 Only some pathological adhesion disorders
2
...
Protective inflammatory response
ii
...
Out of control/non-stop
ii
...
Platelets
 Physiological



i
...
g
...
Thrombosis  occlusion

Leukocyte migration
Margination (has to hit the wall)  contact  capture (selectins)  rolling stop (pick up signal from endothelium,
which activated integrin)  Spread  migrate through (through gaps between endothelial cells)
Circulatory Pathology and Blood Rheology
Red cell rheology:
 Genetic defects in structure  membrane instability
and haemolysis (anaemia)
 Mechanic abnormality:
Sickle cells  haemoglobin S polymer
Malarial parasites  membrane and cytoplasm
 Adhesion abnormality: Malaria (falciparum) Sickle cell
White Rheology:
 Generally: occlusion and/or tissue damage
 Mechanical abnormality:
Vasculitis – autoantibodies
Smoking
Inflammatory mediators (septic shock)
 Uncontrolled Adhesion
o Ischaemia/reperfusion (e
...
myocardial infarction)
o Shock
o Chronic Inflammation
o Graft rejection
o Vasculitis



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