Water Movement Between Body Fluid Compartments

Fill-in-the-blank flashcards covering isotonicity, osmolarity, hypertonic vs. hypotonic solutions, water movement, hormonal regulation (ADH & ANP), dehydration, over-hydration, and water intoxication.

Under normal conditions, body cells neither shrink nor swell because the ECF surrounding them is __.

isotonic

Isotonic solutions have the same __ as the intracellular fluid (ICF).

osmolarity

Water moves by __ from a compartment with lower solute concentration to one with higher solute concentration.

osmosis

A compartment with lower solute concentration (and higher water concentration) is described as __ relative to another compartment.

hypotonic

A compartment with higher solute concentration (and lower water concentration) is described as __ relative to another compartment.

hypertonic

Most changes in extracellular fluid osmolarity are due to alterations in the concentration of __ ions.

sodium

After eating a salty meal, the ECF becomes __ relative to the ICF, causing water to move out of the cells.

hypertonic

When water leaves the cells for the ECF, the immediate effect on cell volume is that cells __.

shrink

Dehydration triggers thirst and the release of __ to conserve water and restore ECF osmolarity.

ADH (antidiuretic hormone)

Drinking large amounts of plain water makes the ECF __ to the ICF, leading to water moving into cells.

hypotonic

An increase in blood volume from excess water intake stimulates the release of __, promoting excretion of large amounts of dilute urine.

ANP (atrial natriuretic peptide)

When water intake exceeds the kidneys’ ability to excrete it, the resulting potentially fatal condition is called __.

water intoxication

Water intoxication is characterized by abnormally low sodium levels in the ECF, a condition termed __.

hyponatremia

Swelling of brain cells from rapid water influx can cause mental confusion, seizures, coma, and possibly __.

death

Clinical rehydration fluids always include __ (e.g., saline) to prevent hyponatremia when replacing body water losses.

salt (sodium)