# Shared Flashcard Set

## Details

Definitions
flux, temp, mechanisms of permeation
23
Physiology
09/16/2009

Term
 Solids
Definition
 each molecule continuously vibrates about an average position that tends to remain pretty well fixed with respect to the average position of neighboring centers of vibration. Long range order
Term
 Gases
Definition
 molecules have translational energy, i.e., the centers of vibration for each molecule are constantly flying about the container, and remain in no fixed position with respect to other centers of vibration. Very short range; dimension of one molecule.
Term
 Liquids
Definition
 intermediate between solid and gas; liquid crystal domain, i.e., regions of a few molecules across where great order prevails, little crystals with molecular dimensions. Within a crystal domain, the centers of vibration of the molecules tend to be constant and we have a little molecular crystal. Short range; dimension of several molecules.
Term
 Temperature
Definition
 a number which is proportional to the avg. kinetic energy of the molecules making up a body. Hence, temp. measures the avg. speed with which the molecules are moving about in a body.
Term
 Kelvin
Definition
 scale where zero point is condition of absolutely no molecular motion. Freezing point of pure water is 273K; increments are the same as the Celsius scale.
Term
 Celsius
Definition
 has as its zero point the freezing point of water
Term
 k (universal Boltzmann's Constant)
Definition
 1.3805*10^-16 erg/K; tells size things must be to have significant velocities. In avg. molecular velocity equation.
Term
 erg
Definition
 amount of energy needed to move 1g, from rest, 1cm, in one second. (g cm^2/s^2)
Term
 Flux
Definition
 rate at which the solute passes through a unit of cross sectional area. (J = mol/s*cm^2) Most important factor affecting flux is concentration of particles.mobility term (D) * driving force (conc. Gradient or voltage gradient)
Term
 Unidirectional flux
Definition
 moving from one side to other
Term
 Net Flux
Definition
 difference between 2 unidirectional fluxes (at equilibrium, = 0)
Term
 Ddiffusion coefficient
Definition
 of the amount of work that must be done to have the solute particle slip through its surrounding solvent molecules; characterizes the migration of particles of a given kind in a given medium at a given temp; surface area flux (J)/conc. gradient; cm^2/s
Term
 Ppermeability coefficient
Definition
 cm/s; use P when don’t know thickness of barrier; Permeability = diffusion coefficient (D)/barrier length (h)
Term
 Interfusion
Definition
 movement of solute particles w/ respect to its surrounding solvent molecules. Defined by driving force. (ex: electrophoresis)
Term
 Convection
Definition
 movement w/ respect to the observer, of the solute particle together with its immediate environment. (ex: movement of molecules in water—osmotic swelling/shrinking)(Convective flux = conc. * volume flow)
Term
 Mechanism of Permeation Type A
Definition
 diffusing through aqueous channels ex: diffusion thru membrane channels, channels controlled by a chemical, or channels controlled by a transmembrane voltage (passive)
Term
 Mechanism of PermeationType B
Definition
 dissolving through lipid phaseEx: diffusion through lipid bilayer (passive)
Term
 Mechanism of PermeationType C
Definition
 carrier mediated transport
Term
 Examples of carrier mediated transport
Definition
 1) facilitated diffusion (passive) 2) active transport (active)(Na/K pump) 3) Symport (codiffusion) – usually tied to Na; links inward flux of Na to inward flux alanine against its conc. gradient; (passive) 4) Antiport (exchange diffusion)—moving Ca uphill as Na moves across passively (passive) 5) Bulk transport—endocytosis (outer part of cellular medium is engulfed and forms own vesicle
Term
 Equilibrium Potential
Definition
 measure in volts; electrical potential; proportional to the log of the ratio of ion conc across membrane. Use Nernst equation to calculate for potential of one ion—would also equal membrane potential if only one ion.
Term
 Membrane potential
Definition
 use Goldman equation (leaves out z term and adds permeability)
Term
 Saltatory Conduction
Definition
 the passage of a potential from node to node of a nerve fiber, rather than along the membrane.
Term
 Kinetic Energy (3 kinds)
Definition
 energy of motion. (rotational, vibrational, translational)
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