TIM STUFF Flashcards
why is the inside of a cell negative?
because the proteins that allow the cell to do everything are present inside and absent outside the cell, so there is a net negative charge causes a skewed distribution of the major ions
which ion is the most permeable? least permeable?
potassium
sodium
what are the two forces that cause an ion to move?
electrical and concentration
sodium has a tendency to move in or out of a cell?what about potassium?
into the cell
out of the cell
what is the equation for total diffusion?
permeability x driving force
what is diffusion like for potassium?
high permeability, low driving force
what is diffusion like for sodium?
low permeability, high driving force
T/F, the membrane potential of a cell will always most closely resemble the Nernst potential of the most permeable ion? what accounts for the difference
T
the contribution of the sodium potassium pump to the resting membrane potential
the sodium potassium can be affected by what substance, causing an immediate 5 mV depolarization to -65?
ouabain
term used to describe the beginning of the action potential when the charge separation across the membrane is being lost and so the membrane potential moves from -50mV up to +30 mV?
depolarization phase
this is the phase of the action potential where the membrane potential returns back to its resting value of -70 mV?
repolarization phase
this is the phase of the membrane potential when It continues to become more negative than the rest at rest?
afterhyperpolarization phase
during the afterhyperpolarization phase, this is the name of the period when threshold will likely be reached again any time soon making it less likely for another action potential?
relative refractory period
how many gates do sodium channels have?
two gates
how many gates do potassium channels have?
one gate
how many gates do non gated potassium channels have?
none, its open all the time
what are the components of the voltage gated sodium channels?
activation gates (outside) inactivation gates (inside) conductance pore selectivity filter voltage sensor
name this part of the voltage gated sodium channel:
only allows sodium to enter the channel? Also a toxin can bind here and block the channel?
selectivity filter
tetrodotoxin
name this part of the voltage gated sodium channel:
not a specific structure of the protein, but recognizes that charges within the protein will shift as the inside of the cell becomes less negative? this leads to the opening of the activation gate
voltage sensor, only about 6 positive charges need to shift in order to open the gate
name this part of the voltage gated sodium channel:
located on the intracellular end of the channel and is open at rest. The inactivation gate closes after the activation gate opens causing sodium conductance through the channel to return to zero, and what period is this?
inactivation gate
absolute refractory period
name this part of the voltage gated sodium channel:
located near the selectivity filter and is closed until threshold is reached. Once opened, both the activation and inactivation gates are open and sodium can pass through the conductance pores
activation gate
what is unique about the voltage gate potassium channels?
similar to sodium but remember:
there is only one gate, which is either open or closed
the charges in the conductance pore are arrange such that they stabilize potassium rather than sodium
name the pharmacological agent that acts o voltage gated channels:
stabilizes the membrane and increases threshold
calcium
name the pharmacological agent that acts o voltage gated channels:
blocks sodium channels from the extracellular side
tetrodotoxin
name the pharmacological agent that acts o voltage gated channels:
lidocaine, procaine and inserts in the conductance pore and block sodium permeability increases
local anesthetic
name the pharmacological agent that acts o voltage gated channels:
from the skin of poisonous frogs, irreversibly opens sodium channels
batrachtotoxin
name the pharmacological agent that acts o voltage gated channels:
block potassium channel opening leading to larger repolarizations
scorpion toxin
name the pharmacological agent that acts o voltage gated channels:
blocks voltage gated potassium channels, but only from the intracellular fluid side of the channel
TEA (tetraethylammonium) same affect like scorpion toxin
T/F, the more action potentials a neuron has, the more ion pumping that it does? what is the affect
T
increase demand of glucose leading to analog 2-deoxyglucose and the development of PET scan
