Questions on inflammation lecture

Here are a couple good questions on Dr. Reinartz’s vascular pressures material – and his answers. 

Q. I had a question from your lecture on inflammation. I was confused on the changes in vascular permeability section. In your lecture slides, you note that hydrostatic pressure is increased while colloid osmotic pressure is decreased. Which pressures do these represent? Starling’s hypothesis addresses four total pressures (2 colloid and 2 hydrostatic).

A. You are correct that there are 4 pressures:

Intravascular

  • hydrostatic pressure
  • colloid osmotic pressure

Extravascular

  • hydrostatic pressure
  • colloid osmotic pressure

I refer primarily to intravascular pressures in my discussion of vascular permeability and edema.

Q. I do not understand why stasis/sludging of the blood–essentially increased viscosity as I take it–could increase intravascular hydrostatic pressure.

A. It’s harder for me to push clotted blood from a syringe than it is to push unclotted blood.  Assuming a similar pushing force, the pressure inside the syringe when pushing clotted blood is greater than the pressure of pushing unclotted blood.

Albumin rich serum serves as the lubricant for cells as they pass through small vessels.  If you loose the lubricant, as occurs in inflammation, it’s harder to get that blood through the small vessels, and pressure builds behind sludging blood.

Great answers! Thanks, Dr. Reinartz. By the way, the material in the syringes is chocolate (bleah). Wonder what the hydrostatic pressure is in those things?

 

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