Question

Hydrostatic pressure:Arterial end =32 mmHg ,venous end=12mmHg.
Colloid osmotic:25 mmHg.
colloid pressure is equal to mean cappilary pressure.


so how
hydrostatic pressure=colloid pressure .
is possible??
​

Answer 1

Pressure differentials govern fluid movement across physiologic membranes. The two forces that contribute are hydrostatic/hydraulic pressure and osmotic pressure. The third factor is the permeability of the capillary membranes. There will be an escape of water and solute into the interstitial space resulting in interstitial edema whenever the hydrostatic pressure is much higher than the osmotic pressure inside the intravascular space. Edema also occurs when there is capillary leakage due to impaired membrane integrity such as in burns or anaphylaxis.

Hydrostatic pressure stems from the action of gravity of a column of fluid while hydraulic pressure refers to the action delivered by a pump. Together, these two forces contribute to blood pressure and fluid movement into and out of the vascular space.[1] Regulation becomes particularly important at the level of the capillary, the point in the circulatory system where permeability exists to both solute and water.

Osmotic pressure relies on selective permeability in membranes. Take two of the major ions of the extracellular fluid: Na+ and Cl-, which can move rapidly between plasma and interstitial fluid spaces, thereby making them ineffective osmotic agents. Proteins, by contrast, are mostly restricted to the plasma compartment, making them effective osmotic agents in the ability to draw water from the interstitial space (where protein concentration is low) to the plasma compartment (where protein concentration is high). The effective osmotic pressure in this example exerted by the plasma proteins on the fluid movement between the two compartments represents colloid osmotic pressure or the plasma oncotic pressure