Diffusion, Osmosis, and Hemodialysis

Vocabulary flashcards covering the principles of diffusion, osmosis, tonicity of solutions, and their clinical applications in red blood cell behavior and hemodialysis.

Diffusion

The movement of solutes from regions of high solute concentration to regions of lower solute concentration, which may or may not occur across a membrane.

Osmosis

The net movement of solvent (water in living systems) across a semipermeable membrane from a solution of lower solute concentration to one of higher solute concentration.

Semipermeable membrane

A membrane that serves as a barrier to diffusion by allowing solvents and small solute particles (such as water, glucose, sodium, potassium, and chloride ions) to pass through while preventing large molecules like proteins from moving in or out.

Isotonic solution

A solution having the same solute concentration as a red blood cell (such as a $5.5\%$ glucose solution or a $0.95\%$ sodium chloride saline solution), resulting in equal flow of water into and out of the cell so it retains its tone.

Hypotonic solution

A solution with a lower solute concentration than an isotonic solution (such as a $2\%$ glucose solution or a $0.5\%$ sodium chloride solution), causing water to flow into red blood cells so they gain water, bloat, and swell.

Hypertonic solution

A solution with a higher solute concentration than an isotonic solution (such as a $10\%$ glucose solution or a $2\%$ sodium chloride solution), causing water to flow out of red blood cells so they shrink.

Crenation

The process where red blood cells lose water, appear dehydrated, and shrink in size when placed in a hypertonic solution.

Hemolysis

The process where red blood cells absorb water, swell, appear larger in size, and eventually burst when placed in a hypotonic solution.

Hemodialysis

A clinical application of diffusion used to clean the blood of patients with malfunctioning kidneys by pumping blood through long semipermeable dialysis tubing placed in an isotonic bath.

Dialysis solution

An isotonic solution formulated with many of the same solutes as blood plasma (such as $5.5\%$ glucose and $0.95\%$ saline) that continuously carries away diffused waste products like urea while keeping large proteins like hemoglobin in the blood.