Which components in blood affect viscosity?

Which components in blood affect viscosity?

• A. White blood cells, red blood cells, platelets, and proteins suspended in plasma
• B. Only red blood cells
• C. Only white blood cells
• D. Platelets and plasma proteins

Answer: (A)

Blood viscosity is set by how many particles are in the blood and how they interact, not just by one type of component. The amount of red blood cells (hematocrit) and the concentration of plasma proteins are the main drivers: more cells and higher protein content increase internal friction and raise viscosity. Red blood cells are the most influential because they are so numerous, so their concentration largely determines flow resistance. White blood cells and platelets add to the solid content of blood; although they are fewer in number, changes in their levels or their tendency to cluster can raise viscosity, especially in states of inflammation or disease. Plasma proteins, particularly fibrinogen, increase plasma viscosity directly and also promote red cell aggregation (rouleaux), further increasing whole-blood viscosity. So including white blood cells, red blood cells, platelets, and plasma proteins captures all the components that can affect viscosity.

Blood viscosity is set by how many particles are in the blood and how they interact, not just by one type of component. The amount of red blood cells (hematocrit) and the concentration of plasma proteins are the main drivers: more cells and higher protein content increase internal friction and raise viscosity. Red blood cells are the most influential because they are so numerous, so their concentration largely determines flow resistance. White blood cells and platelets add to the solid content of blood; although they are fewer in number, changes in their levels or their tendency to cluster can raise viscosity, especially in states of inflammation or disease. Plasma proteins, particularly fibrinogen, increase plasma viscosity directly and also promote red cell aggregation (rouleaux), further increasing whole-blood viscosity. So including white blood cells, red blood cells, platelets, and plasma proteins captures all the components that can affect viscosity.