(LE 2) Interactions Between Cells & the Extracellular Environment Flashcards
What is diffusion rate dependent on?
- magnitude of concentration gradient
- permeability of membrane (directly related)
- temperature (directly proportional)
- membrane surface area (microvilli; directly related)
- molecule size (inversely proportional)
What is carrier-mediated transport?
uses specific protein transporters
- facilitate diffusion (no energy)
- active transport (against gradient; req ATP)
What is molecular weight?
atomic weight of all atoms in compound
What is a mole?
6.02 x 10^23
1 mole = mw of a compound in grams
What is 1 molar solution?
1 mole of solute dissolved in 1L of solution
What is 1 molal solution?
1 mole of solute dissolved with 1L of solution
What is osmolality?
total molality of a solution
What is Osm related to the freezing point of a solution?
Freezing point dependent on solution concentration
- 1 molal solution depresses freezing point of water by -1.86° C
What is the Osm of blood?
0.3 Osm = 300 mOsm
How does the body regulate blood osmolality?
What is facilitated diffusion?
passive transport down concentration gradient by carrier proteins
- increase permeability
What do carrier-mediated transport proteins exhibit?
specificity: for single molecule
competition: among substrates for transport
saturation: when all carriers are occupied (Tm: transport maximum)
What is required for active transport?
ATP and carrier protein
What is the Na+/K+ pump?
Uses ATP to move 3 Na+ out and 2 K+ in against their gradients
What is secondary active transport?
movement of a molecule down its gradient coupled to the movement of another molecule against its gradient
What is cotransport?
symport; transport of molecules in same direction. common way to transport glucose
What is countertransport?
antiport; transport of molecule in the opposite direction
What is transcellular transport?
movement of molecules through the cytoplasm of the epithelial cells
What is paracellular transport?
movement across the tiny gaps between cells of epithelial membrane
How do you limit paracellular transport?
by junctional complexes
