Movement of Substances (Terms)
Selectively Permeable Membrane
A Selectivley Permeable Membrane allows only specific substances to pass.
Solvent
The substance whose movement is being described may be water.
Solute
The substance dissolved in the water.
Down the Concentration Gradient
Movement of substances may occur from higher to lower concentration.
Against the Gradient
The reverse of Down the Concentration Gradient.
Hypertonic
A higher concentration of solutes.
Isotonic
An equal concentration of solutes.
Passive or Active Movement
Active movement requires the expenditure of energy and usually up a gradient.
Bulk Flow
Bulk flow is the collective movement of substances in the same direction in response to a force or pressure.
Passive Transport Processes
Diffusion
Diffusion is the net movement of substances from an area of higher concentration to an area of lower concentration.
Osmosis
Osmosis is the diffusion of water molecules across a selectively permeable membrane.
Dialysis
Dialysis is the diffusion of solutes across a selectively permeable membrane.
Plasmolysis
Plasmolysis is the movement of water out of a cell (osmosis) that results in a collapse of the cell.
Facilitated Diffusion
Facilitated diffusion is the diffusion of solutes through channel proteins in the plasma membrane.
Countercurrent Exchange
Countercurrent Exchange describes the diffusion of substances between two regions in which substances are moving by bulk flow in opposite directions.
Vesicular Transport
- Exocytsis
- Endocytosis
- Phagocytosis
- Pinocytosis
- Receptor-mediated Endocytosis