Lecture 2: Membrane Potentials Flashcards
Most of the bodies solutes are ___ and thus carry a ____ charge
Ions
Net Electrical
Cause ions to move across cell membranes
Gradients
Separation of ___ takes place across the membrane
Charge
The electrical potential is called the
Membrane potential
Membrane potentials are determined by 3 factors:
1. _____ of ions on the inside and outside
of the cell.
2. ____ of the cell membranes to those
ions through ion channels
3. Activity of _____ that maintain
[ion] across the membranes
Concentration
Permeability
Electrogenic pumps
All cells have different concentrations of ___ across the membrane (esp Na+, K+, Cl-), as well as ____ charged proteins to which the cell membrane is ____
Ions
Negatively
Impermeable
Typical resting potential is ___ mV
70
Resting membrane potential: Constant membrane potential in:
• ____ cells
•____ cells at rest
Nonexcitable
Excitable
Minus sign means inside of cell is ___ compared to outside
Negative
Ions responsible for generating resting potential are the cations ___ and ___, as well as____ anions.
Na+ and K+
intracellular
Na+ greater concentration in the ___, moderate permeability
• K+ higher concentration in the ___, high permeability
• A- only in the ___, no permeability
ECF
ICF
ICF
The Na+–K+ pump: __ Na+ out of the
cell for every 2___K+ in
•Inside becomes ___ compared to
outside
•Primary role of the pump is to actively
___ Na+ and K+ concentration
gradients
- 2
NEGATIVE
MAINTAIN
In a cell that is permeable to just one ion, the membrane potential that exactly opposes the concentration gradient is called the _____
or E(ion)
equilibrium potentiaL
The greater the ____ of
the plasma membrane for a
given ion, the greater the
tendency for that ion to drive
the membrane potential toward
the ion’s own ____
potential
Permeability
Equilibrium
At rest, a membrane is 50-75
times as permeable to
___, therefore ____
influences resting membrane
potential to a greater extent
Potassium
Potassium
Nerve and muscles cells are excitable cells and can change their resting membrane potential to produce ______
Electrical signals
Neurons use signals to receive, process, initiate, and transmit ____
◦ Muscle cells use signals initiate ___ ___
Messages
Muscle contractions
Changes in membrane potential are brought about by ___ movements
• Net inward flow of +ve ions compared with resting state → _____
• Net outward flow of +ve ions compared with resting state →_____
Ion
Depolarization
Hyperpolarization
______: membrane becomes less polarized than at resting potential
_______: membrane returns to resting potential after having been depolarized
_____: membrane becomes more polarized than at resting potential
Depolarization
Repolarization
Hyperpolarization
Recall that ions can only cross membranes via specific ____
Channels
Types of gated channels:
1. ____ gated
2. _____ gated
3. ____ gated
4. _____ gated
Voltage
Chemically
Mechanically
Thermally
2 basic forms of electrical signals
• ____ potentials
• _____ potentials
Graded
Action
_____ potentials
Local changes in membrane potential
•Occur in a small, specialized region of excitable cell membranes
•Usually produced by specific triggering events that causes gated ion channels to open in a
specialized region of the membrane generally chemically- or mechanically–gated
Graded
The magnitude of this
graded potential is related to
the magnitude of the
____ event
• The _____ the trigger, the
larger the _____
graded potential
• The ____ the duration of
the triggering event, the
longer the duration of the
_____ potential
Triggering
Stronger
Depolarizing
Longer
Graded
Current can be ___ across membrane
• Because of this leak, the local current
progressively _____ with increasing
distance from origin
• Graded potentials have limited
signaling ____
Lost
Decreases
Distance
Graded potentials can sum to
initiate ______
Action potentials
The ____ equation is used to calculate the resting membrane potential that results from the contribution of all ions that can cross the membrane
GHK - Goldman-Hodgkin-Katz equation
