Module 2: Fluids Flashcards
What are the two major fluid compartments?
The intracellular fluid compartment is all the fluid inside the cells; this ICF does not count towards the internal environment of the body. The extracellular fluid compartment is all the fluid outside of the cells; this ECF is is also what makes up the internal environment of the body.
What are the two divisions of the extracellular fluid?
The interstitial fluid compartment is the fluid directly outside that baths the cells. The plasma is the watery portion of the blood.
What is the distribution of total body water (TBW)?
For an average 70 kg person, TBW is 42 L:
- 28 L from the ICF
- 11 L from the interstitial compartment of the ECF
- 3 L from the plasma compartment of the ECF
What is the makeup of plasma?
Plasma is a pale yellow fluid consisting of 92% water and 8% other substances, including proteins, ions, nutrients, gases, and waste products. Plasma does not contain cells.
Plasma is a colloidal solution, which is a liquid containing suspended substances that do not settle out of solution. Most of the suspended substances are plasma proteins, which include albumins, globulins and fibrinogen.
Plasma volume remains relatively constant. This is because water intake through the digestive tract closely matches the water loss through the kidneys, lungs, digestive tract and skin.
What are the relative distributions of ions between the inside and outside of the cell?
There are large differences in the concentration of ions between the intracellular fluid and the extracellular fluid.
- More Na+ outside of the cell
- More Ca++ outside of the cell
- More Cl- outside of the cell
- More Pr (protein ions) inside of the cell
- More K++ inside of the cell
The concentration of ions between the interstitial fluid compartment and the plasma is similar.
Why is there a difference in the ionic composition between the inside and the outside of the cell?
The cell membrane is a physical barrier between the intracellular fluid and the extracellular fluid. This membrane is selectively permeable. The membrane has channels, pores, and special transport systems that regulate the passage of molecules across the membrane.
