Question

1. What are the main forces that are responsible for filtration and reabsorption? What provides these forces? Does mors filtration or reabsorption occur?

2. What happens when there is more fluid forced out at the capillary than is reabsorbed?

a) What happens if this system is disturbed by

trauma or surgery?

Answer 1

There are two type of forces whih determine the filtration and reaborption between capilary and interstitium.

1. Hydrostatic pressure - hydrostatic pressure is the pressure which is exerted by fluid inside the capillary or

interstitium. it is the positive force which causes movement of fluid out from the capillary.

2. Colloid Osmotic pressure (Oncotic pressure)- it is determined by plasma protein concentration and it is the major negative force

So net movement of fluid is determined by balance between hydrostatic pressure.

Net filtration pressure -- (Force A- Force B)

(Capillary Hydrostatic pressure + Interstitial oncotic pressure ) - (Capillary oncotic pressure + Interstitial hydrostatic Pressure)

Usually interstitial oncotic pressure is Nil as there is usually no plasma protein in the interstitium.

So if force A is more than Force B Filtration occurs.

Ans 2.If more fluid is forced out from the capillary than reabsorbed, it will lead to accumulation of fluid in the tissue interstitim and will lead to oedema

if this system is disturbed by trauma or surgery the outcome wil depend upon netfiltration pressure.

if netfiltrtion is more it will lead to oedema