Flashcards in Ch 5 Membrane Potential and Action Potential Deck (28):
membrane potential following an action potential.
Which ions are actively concentrated within and which extruded to generate membrane potential?
K+: in. Na+, Cl-, and Ca2+: out
the membrane potential at which the net current flips
difference in electrical potential between the interior and exterior of cells
grand mal/tonic-clonic seizure
large numbers of neurons on the cerebral cortex dump K+
Na+ -K+ pump
moves Na+ out of the cell while moving -K+ in through hydrolysis
K+ ions flowing out due to concentration gradient is offset by K+ ions entering due to negative potential inside the cell
How many Na to K are transferred in the pump?
3 Na for 2 K
Na+ Ca2+ exchanger
keeps Ca low inside the cell by exchanging 1 for 1
3 properties that influence passive charge response
membrane resistance, axial resistance, membrane capacitance
the ability to store electrical charge
resistance in the movement of axial current due to properties of organelles and cytoplasm
the point at which membrane potential drops to 37%
Tetradotoxin, poison found in the pufferfish that blocks voltage dependent Na+ currents
differences in Na and K action potentials
K+ current activates slowly. Na+ activates and deactivates rapidly.
genetic material is changed in a stable manner
Graded Potential, 3 things...
1)Depolarization or hyperpolarization
2)Travel short distances
3) Lose strength as travel through cell
Action potential, 3 things...
1) Large uniform depolarizations
2) Travel rapidly without losing strength
3) Travel long distances
Where do graded potentials begin?
Dendrites or cell body at point of ion entry
In a graded potential what determines amplitude size. hyperpolarization?
More Na+ channels open, higher amplitude. K+ open, hyperpolarization.
Where the action potential occurs, where there are a lot of sodium channels.
Where are the trigger zones?
MOTOR neurons: axon hillock. SENSORY neurons, the 1st unmyelinated area (first node of ranvier).
What do axon potentials result from?
Changes in membrane permeability to Na+ and K+
3 phases of an action potential
1. rising (Na+ open) 2. falling (K+ channels open) 3. hyperpolarization (due to excess K+)
Na channel gates, resting vs. depolarized
Resting: Activation gate closed/inactivation gate open.
Depolarized: opens activation gate and opens channel
Which ions are usually high inside and low outside?
Potassium and Phosphates
Which ions are usually low inside and high outside?
Sodium and Chloride