BIOPHYSICS N°12 (FILL)

At equilibrium, the chemical and electrical potential differences across the

membrane are .......... but ...........

equal, opposite

........... is a measure of the work needed to move a test charge q0 between two

points 1 and 2 in an electrical field

electric potential energy

A solute X is at equilibrium when the electrochemical potential difference for that

solute across the membrane is ...........

zero

The electric field vector E is defined as ............ where ............

E = F/q

F = force

q = charge

According to the Ohm's law, the voltage and current are directly related to each

other by ..........

V = I x R

All body solutions must follows the principle of ............: the number of

positive charges in the overall solution must be the same as the number of negative

charges

Electro neutrality

The flux of any ion can be described by the electro diffusion equation of ...........

Nernst-Plunk molar flux equation

The mobility and diffusion coefficient are related by the ............ equation

Einstein

In an ion is at electrochemical equilibrium, then du*= ..........

zero

Suppose the electrical potential difference across a membrane is 70mV. To find the strength of the field we need to use the following formula: .............

E = F/q

One mole of monovalent ions has the charge of .............

1 Faraday or 96500 C

The electrochemical potential of the permeable ions can be calculated using the following equation: .............

μ* = μ0 + RT ln C + zFɸ

For KCl solutions the diffusion potential can be taken as .............

Equilibrium

When the diffusion potential attains a maximum value, the electric current across

the membrane is ............ since the flux of the anions equals that of cations

zero

The diameter of the alkali metal ions and their mobilities ............ on proceeding

from Li+ to Cs+

increase

The principal intracellular cation is ............

K+

The ............. is created by a difference in charge across a membrane

Membrane potential

The important factors for the establishment of equilibrium membrane potential

are:

a)..........

b)..........

c)...........

a) temperature

b) concentration gradient

c) valence of the ionic species in question

The important factors for the establishment of diffusion potential are:

a)..........

b)..........

c)...........

a) different mobility of ions

b) concentration

c) ion valency

The important factors for the establishment of Donnan potential are:

a)..........

b)..........

c)...........

a) different concentration

b) electrochemical equilibrium

c) permeability

Ions may move directionally across a membrane even in the absence of

concentration gradient

gradient

To use the Nernst equation we must know the valence of the ion and ...........

their concentration inside and outside

To reduce the K+ gradient we need to ............. the intracellular K+ or .............

the extracellular K+

decrease, increase

The Ek of a cell is about ...........

-92 mV

The equation that describe this balance of electrical and chemical forces is called ............

Nernst equilibrium equation

When inserting the relevant for R, T, F and z, and to convert from natural logs

to base 10 logs, the Nernst equation can be written in the following way: .............

Em = -60 log C2/C1

The amount of K+ that leaves the cell to produce the equilibrium potential ..............

70 mV

The reduction of K+ gradient will ........... the equilibrium potential for K+

Decrease

The net ion flux that correspond to the equilibrium membrane potential is ............

Zero

............... coulombs of charge pass through a cell if 3.0 amperes of current are passed

through the cell for 10 minutes.

1800 C (Q = I x f = 3A-6005 = 1800 As = 1800C)

The universal gas constant can be calculated by multiplying ........... by ...........

P by V