Osmosis and Tonicity Flashcards
What is osmosis?
he movement of water across a membrane from low particle concentration to high particle concentration.
What are aquaporins?
pecialized protein channels in the cell membrane that facilitate the movement of water.
How does NaCl contribute to osmotic concentration?
NaCl dissociates into two particles (Na⁺ and Cl⁻), doubling its osmotic effect.
What is tonicity?
The response of cells to the osmotic concentration and permeability of external solutions.
What happens to cells in an isotonic solution?
They maintain their volume because the osmotic concentration is equal to intracellular fluid.
Describe a hypertonic solution’s effect on cells.
Cells lose water and shrivel because the solution has a higher osmotic concentration than the intracellular fluid.
What occurs when cells are placed in a hypotonic solution?
They take in water, swell, and may burst if the solutes are impermeable.
What is the reflection coefficient?
A measure of a solute’s ability to cross the membrane (1 = impermeable, 0 = freely permeable).
What drives water movement during osmosis?
Electrical charges of particles, protein charges near aquaporin pores, and Brownian motion.
What happens when a permeable solute is more concentrated outside the cell?
The solute enters the cell and creates a hypotonic effect, even if the overall osmolality suggests otherwise.
