The Neuronal Membrane At Rest

Front 1

Excitable membrane

Back 1

Cells capable of generating and conducting action potentials (nerve & muscle cells)

Front 2

Resting membrane potential

Back 2

Aka resting potential. Difference in electrical charge across the membrane. Cytosol inside has a negative electrical charge compared to the outside.

Front 3

Action potential

Back 3

A brief reversal of the resting potential such that inside is positive relative to the outside.

Front 4

Ions

Back 4

Atoms/molecules that have a net electrical charge.

Front 5

Cations

Back 5

Positively charged ions

Front 6

Anions

Back 6

Negatively charged ions

Front 7

Phospholipid bilayer

Back 7

A stable arrangement of proteins creating the membrane. Hydrophilic heads face outer/inner watery environment and hydrophobic heads face each other (away from water)

Front 8

Peptide bonds

Back 8

Connect amino acid chains. Join the amino group to the carboxyl group

Front 9

4 Levels of Protein Structure

Back 9

Primary, Secondary, Tertiary, Quaternary

Front 10

Ion channels

Back 10

Made from membrane spanning protein molecules. 4-6 proteins.

Front 11

Ion selectivity

Back 11

Specified by pore diameter and R groups lining the channel. Determines which ions may pass through.

Front 12

Gating

Back 12

Opening/closing of channels. Result of changes in the local microenvironment of the membrane.

Front 13

Diffusion

Back 13

A net movement of ions from regions of high concentration to regions of low concentration.

Front 14

Concentration gradient

Back 14

Difference in concentration. Moves from areas of high concentration to areas of low concentration.

Front 15

Electrical current

Back 15

Movement of an electrical charge

Front 16

Electrical potential

Back 16

Also called voltage. Force exerted on a charged particle and it reflects the difference in charge between the anode and the cathode.

Front 17

Electrical conductance

Back 17

Relative ability of an electrical charge to migrate frm on point to another. Represented by the symbol g and is measured in Siemens (S)

Front 18

Electrical resistance

Back 18

Relative inability of an electrical charge to migrate. Represented by symbol R and is measured in ohms. R = 1/g

Front 19

Ohm's Law

Back 19

I = gV (aka. Current is the product of the conductances and the potential difference.

Front 20

Membrane potential

Back 20

Voltage across the neuronal membrane at any moment, represented by the symbol Vm.

Front 21

Microelectrode

Back 21

Thin glass tube with an extremely fine tip. Will penetrate the membrane of a neuron with minimal damage. Filled with an electricall conductive salt solution and connected to a device called a voltmeter.

Front 22

Ionic equilibrium potential

Back 22

Electrical potential difference that exactly balances an ionic concentration gradient (aka Equilibrium potential)

Front 23

Nernst equation

Back 23

Exact value of equilibrium potential.
E[ion] = 2.303 (RT/FT)log [ion]o/[ion]i

Front 24

Sodium-Potassium Pump

Back 24

An enzyme that breaks down ATP in the presence of internal Na+. The chemiacl energy released by this reaction drives the pump, whichexchanges intenral Na+ for external L+. Ensure that K+ is concentrated outside the cell and that Na+ concentrated inside the cell. Requires expenditure of metabolic energy.

Front 25

Calcium pump

Back 25

Enxyme that activiely transports Ca2+ out of the cytosol across the celll membrane.

Front 26

Ion pumps

Back 26

Ensure that the ionic concentration gradients are established and maintained. Wihtout ion pumps, the resting membrane potential would not exist, and the brain would not function.

Front 27

Goldman equation

Back 27

A mathemtatical formula that takes into consideration the relative permeability of the membrane to different ions.

Front 28

Depolarization

Back 28

A change in membrane potential from the normal resting value (-65mV) to a less negative value. Increasing extracellular potassium depolarizes neurons.

Front 29

Blood-brain barrier

Back 29

Helps to tightly regulate extracellular protein concentrations in the brain. Specialization of the walls of brain capillaries that limits the movement of potassium (and other bloodborne substances) into the extracellular fluid of the brain.