Physiology chapter 2-Unassisted membrane transport Flashcards
Molecules that can penetrate the plasma membrane on their own do so by which two forces?
Diffusion down a concentration gradient and movement along an electrical gradient.
What is diffusion?
Uniform spreading out of molecules along a concentration gradient.
What is a concentration gradient (chemical gradient)?
Difference in concentration of a molecule that allows for diffusion with a semi-permeable membrane.
What is net diffusion?
Total diffusion from both a concentration gradient and electrical gradient.
What is steady state, in regards to diffusion?
When diffusion rates of molecules are even in both directions.
What is an electrical gradient?
A difference in charge between two adjacent areas that promotes movement of ions toward the area of opposite charge.
What is osmosis?
The diffusion of water across a permeable membrane. Water goes toward an area of higher solute concentration.
What are aquaporins?
Channels used for the passage of water along a concentration gradient.
What is tonicity?
The effect a solution has on cell volume. This is determined by the concentration of non-penetrating solutes in solution.
What is an isotonic solution?
Solution with an equal concentration of non-penetrating solutes as that in the cell.
What is a hypotonic solution?
Solution with a lower concentration of non-penetrating solutes as that in the cell.
What is a hypertonic solution?
Solution with a higher concentration of non-penetrating solutes as that in the cell.
What is the result of a cell being in a hypotonic solution?
Cell swells. Water enters.
What is the result of a cell being in a hypertonic solution?
Cell shrinks. water leaves.
