Lecture 3 - Movement Of Water Across Membranes Flashcards
What is osmosis?
Osmosis refers to the diffusional movement of water.
Can be thought of as the proportion of a solution that is water
What is osmotic pressure?
Osmotic pressure is the external pressure that is required to prevent the osmotic flux of water.
What is osmolality?
Osmolality is the measure of the total number of osmotically active solutes in a solution (units: osmoles L-1)
What is water flux determined by?
Water flux is determined by the hydraulic conductivity, how easily the fluid moves, area, and the driving force for H2O movement.
What is hydraulic conductivity?
Relative water flow
What is the driving force for H2O movement determined by in cell membranes?
Osmotic pressure
What are aquaporins?
Aquaporins are water channels that increase the hydraulic conductivity of a membrane
What is osmolarity?
Osmolarity refers to the number of osmotically active molecules dissolved in a solution. It helps give us an indication of where water wants to go.
What is tonicity?
Tonicity is the relative solute concentration of two solutions separated by a membrane. Tonicity tells us the effect a solution has on cells and considers the ability molecules have to cross the cell membrane.
What does isosmotic refer to?
When the osmolarity inside and outside of the cell is the same
What does hyperosmotic refer to?
When osmolarity outside of the cell is higher than inside the cell.
What does hypo-osmotic refer to?
When osmolarity inside the cell is higher than outside of the cell.
What differs in osmolarity?
Osmolarity inside the cell is always the same, external osmolarity differs
What does an isotonic solution do to cells?
An isotonic solution has no effect on cells
What does a hypertonic solution do to cells?
A hypertonic solution shrinks cells
