###### Created: 2024-01-13 13:30 ###### Areas & Topics: #medicine #physics #physiology ###### Note Type: #permanent ###### Connected to: [[]] - In simple terms, a colloid is a mixture of two substances. - One of these substances is suspended (i.e. kept within) through another substance. - In colloids, the substance that is suspended is made up of microscopic particles (less than 1nm typically) that are insoluble and dispersed throughout the suspension. - In colloids there is a dispersion medium and something being dispersed ### Blood as a Colloid - In [[capillary]] blood, the plasma acts as the dispersion medium. - The blood cells and other smaller constituents of blood are the insoluble particles that are being dispersed (which are all suspended in the plasma). - These particles are able to move in and out of the capillaries and tissues based on their concentration gradient (i.e. the particles and substances move from where there is more of them to where there is less of them to try and reach equilibrium) - This exerts pressure on the walls of [[Capillaries]] known as the colloid osmotic or oncotic pressure - The colloid structure of blood is significant because this, in combination with hydrostatic pressure, is the only effective way for substances to move between capillaries and tissues whilst maintaining homeostasis (i.e. keeping everything in the body well regulated). ![[2108_Capillary_Exchange-1.jpg]] ### Resources https://en.wikipedia.org/wiki/Colloid#In_biology