Body Fluid Compartments II

Practice flashcards covering key concepts of body fluid compartments, osmolality, and fluid dynamics.

What is osmolality in body fluids?

The concentration of solutes in body fluids, determined by the number of free (dissociated) particles in solution.

How does osmolality relate to water movement?

Water movement is passive and driven by osmotic gradients, moving from areas of low solute concentration to high.

What are the three types of fluid volume changes?

Hypotonic, isotonic, and hypertonic expansions or contractions.

What determines the majority of ECF osmolality?

Electrolytes (ions) that dissociate in solution, primarily sodium chloride (NaCl).

What is the consequence of NaCl being 'impermeable'?

It generates a sustained osmotic effect with no net movement of water.

What happens during hypotonic expansion?

Both ECF and ICF expand, causing a fall in osmolality and cell swelling.

What occurs with isotonic expansion?

Only ECF expands without a change in osmolality, leading to edema.

What results from hypertonic expansion?

Increased ECF osmolality, water moves out of cells, causing cell shrinkage.

What describes a hypertonic contraction?

Heavy sweating leads to loss of water without equivalent NaCl loss, decreasing both ECF and ICF volumes.

What is the physiological role of Na+ ions in plasma?

Directional changes in plasma Na+ concentration indicate osmotic changes affecting fluid volume.

Why can't pure water be infused intravenously?

Infusion of pure water causes cell swelling and potential bursting, leading to hyperkalemia.

What should be infused instead of pure water?

A 5% glucose solution which mimics water without causing cell lysis.

What is the long-term role of the kidneys in body fluid balance?

The kidneys maintain constant volume and composition of body fluids.

What happens to ICF volume when ECF osmolality rises?

Water leaves the cells, causing a fall in ICF volume and an increase in ICF osmolality.