Body Fluid Compartments and Fluid Balance. Objectives. 1. Differentiate between the terms osmole, osmolarity, osmolality and tonicity. 2. List the typical value and normal range for plasma osmolality.
-1 Mol OF Glucose solution?
- 1 Mol NaCl solution?
In the ECF, max contribution to
Osmolalirty is by NaCl
Osmosis: Diffusion of H2O
Across semi permeable
membrane From high H2O
concentration to low
H2O concentration. In tissues
- via lipid bilayer
-Through water channels
Movement of H2O
Osmotic pressure is the
pressure which is applied
at the membrane to
Osmotic pressure is directly proportional
To the osmolarity (solute concentration)
Pressure = 2 mmHg
Pressure = 30 mmHg
Osmosis is the net movement of water molecules through a selectively permeable membrane
During osmosis water molecules pass through a selectively permeable membrane in two ways (1) through the lipid bilayer and (2) through aquaporins (aqua = water) channels.
The osmosis, diffusion, filtration and reabsoption provide for continual exchange of water and solutes (electrolytes) among different body compartments
Yet, the volume of the fluid in different body compartments remains remarkably stable
ECF also includes lymph, CSF, synovial fluid, aqueous & vitreous humor, endolymph & perilymph and fuild present in pleural, pericardial and peritoneal cavities