Water movement Flashcards
Total body water composition
60%
What are the two body fluid compartments?
- Intracellular fluid (40%)
- Extracellular fluid (20%)
What are the compartments of the extracellular fluid?
- Interstitial fluid (15%)
- Transcellular fluid
- Intravascular fluid (5%)
What is the most important function of the kidney?
Maintain composition and volume of the ECF
What are some forces that act on body fluids?
- Osmotic force
- Hydrostatic pressure
- Oncotic pressure
What is the result of osmotic pressure?
Movement of a fluid across a semi-permeable membrane that equalize concentration of solute on either side of the membrane
What type of cell are the most water permeant?
RBC
What are the components of blood?
- Cells (RBC)
- Plasma (IVF)
What is hematocrit?
Amount of RBC in the blood
How can water permeate a membrane?
- Diffuse through the bilayer (slow)
- Aquaporins (fast)
What is hydrostatic pressure?
Movement within the ECF compartments. Determined by blood pressure from pumping of the heart
What is oncotic pressure (colloid osmotic pressure)?
Pressure exerted by large molecules in a solution within ECF compartments
What factors favor movement out of capillary?
Hydrostatic pressure in the capillary and interstitial oncotic pressure
What factors favor movement into the capillary?
Interstitial hydrostatic pressure and capillary oncotic pressure
How do you measure volume of a given body fluid compartment?
Dilution method
