Resting Membrane Potential Flashcards
What is the electrochemical gradient?
Differences in both electrical potential and chemical concentrations across a membrane
What is excitability?
He ability of a cell to generate an electrical signal
What cells generate electrical signals?
Brain, muscles, and the heart
What is electronegativity?
The ability to greatly attract electrons in covalent bonds
What is ionization (dissociation)?
Process of breaking ionic bonds as ions interact with water molecule
What are ions?
Polar molecules. Where one side is “partially positive” (losing a large fraction of electron), where one side is “partially negative” (gaining a large fraction of electron)
What is diffusion?
Ions/molecules move down their concentration gradient from high to low
What is an electrical gradient?
Area where the overall charge of one location is higher than another
What is an electrical current?
The movement of ions (diffusion of ions caused by electrical and chemical gradients)
What is an electrical potential?
Refers to the difference in charge between two points
What are plasma membranes?
Selectively permeable barrier separating inside of cell from extra cellular fluid
What is the fluid mosaic model of a plasma membrane?
Multiple diverse and mobile components make up the cell membrane
What does it mean if a plasma membrane is selective permeable?
Only certain molecules or ions can pass through it
What is a phospholipid bilayer?
Two layers of phospholipids, hydrophilic heads at surface and hydrophobic tails on inside
What are ion channels?
Specialized proteins in our cell membranes that allow ions to diffuse down concentration gradient. They are selectively permeable to certain ions
What do transmembrane proteins allow for?
The passage of ions across the membrane
Where can proteins exist?
In closed, open or inactive days states
What are closed proteins?
Refers to proteins that havent been stimulated
what are open proteins?
Refers to proteins that have been stimulated and are passing ions
What are inactivated proteins?
Proteins that are being stimulated but have become “desensitized” to the stimulus and are no longer passing ions
What do ion channels do?
Act as “gates” in an otherwise impermeable membrane “fence”
What are some types of ion channels?
Ligand gated- neurotransmitters open
Voltage gated- activated by voltage change
Stretch and heat gated- hot/cold
T/F ion channels do not indiscriminately pass all ions down their concentration gradient
True: ion channels either exclusively pass anions or cations. Some ion channels are selective and can only pass one type of ion
what are ion pumps?
Transporters that use energy
Which pump changes the resting membrane potential?
Sodium potassium pump
What occurs in the sodium potassium pump?
3 sodium ions are moved out against their concentration gradient while 2 potassium ions are moved in against their concentration gradient (requires hydrolysis of ATP)
What do the unequal exchange of charges in the sodium potassium pump help to do what?
Maintain the negative resting potential
What are active transporters?
Actively move selected ions against concentration gradient, create ion concentration gradients
What is excitability?
The ability of a membrane to conduct electrical charges in order thus creating the membrane potential (relies on the presence and ability to activate ion channels in the membrane)
What is the resting membrane potential?
The difference in electrical charges across the membrane when there is no electrical current
What determines the sign on the inside of the celll?
The direction of the charge
If more positive on the inside the sign is +
If more positive on the outside the sign is -
What is electrophysiology?
The ability for electrical current to generate a physiological output
What is Ohm’s law?
V=IR
V= voltage
I= current
R= resistance
How can we alter the electrical current?
Change voltage- role of iconic concentrations
Change conductance- role of # of channels, role of channel properties
How do we measure the electrical potential?
Use a voltmeter
How does a voltmeter measure the membrane potential?
Microelectrode is placed inside the cell and the potential difference is determined by comparing to a ground placed in the bathing solution outside the cell
What is the normal resting membrane potential?
-70 mV
How can we change the resting membrane potential?
A change in the concentration of iconic species on either side of the membrane, the membrane potential will change
T/F only small ionic fluxes lead to large and local changes in membrane potential
True a shift of 80 mV can be caused by a concentration change of only 0.000001 mM
How do we determine the equilibrium potential for a particular ion?
Nernst equation
What is the nearest equation?
Eion=61.54 log (ion out/ion in)
What is the GHK equation used for?
Determining the overall resting membrane potential
What is the GHK equation?
MV= 61.54 log (((Pk * K out) + (PNa * Na out) + (PCl * Cl in))/((Pk *K in) + (PNa * Na in) + ( PCl * Cl out)))
