Lecture 2 Flashcards
do neurons have a negative or postive membrane potential at rest?
negative
do all neurons have the same resting membrane potential
no
what is the average membrane potential
(-40)-(-90)mv
define resting membrane potential
neurons have a negative voltage potential at rest called the resting membrane potential
do substances move up or down their concentration gradient?
down
in simple diffusion do things move from high to low or low to high concentrations
high to low
define diffusion
substances naturall and passivel travel down thier concentration gradients (areas of higher concentration to areas of lower concentration )
is the plasma membrane a good or bad conductor of ions
good
what is the purpose of the plasma membrane
allows the neuron to maintain different concetrations of ions and other molecules inside and outside of cell
what are the 2 ways that ions cross a plasma membrane
ion channels and ion pumps
do ion channels use active or passive transport
passive transport
can anything pass thorugh a ion channel or is it selective
it is selective for certain ions
do ion pumps have active or passive transport
active transport
is atp needed for ion channels
no , it is passive transport
is atp needed fo ion pumps
yes,it is active transport
do ion pumps create concentration gradients ?
yes
are ion pumps selective for certain ions
yes
do ion pumps do up or down the concentration gradient
It can go up the gradient , so from low to high
name the pump that is responsible for the origin of membrane potential
sodium potassium pump
describe what the sodium potassium pump does
it creates a concentration gradient for sodium and potassium
explain what is going out of a cell and what is coming into a cell due to a sodium potassium pump
3 sodium out and 2 potassium in
true/false : a sodium potassium pump does not use atp
false it uses atp
true /false: there is higher concentration of k inside of the cell
true
true/false: there is a higher concentration of na inside of the cell
false, there is a higher concentration outside of the cell
when a cell is at rest , are potassium channels open ?
yes
when the potassium pump is at rest a sodium channels open ?
no
there is a negative charge on the outside of the cell, t/f
false , the inside of the cell is negative
when a cell is at rest, what can leak out of the cell
potassium
the sodium potassium pump creates a _____ _______
concentration gradient
are there more sodium or potassium pumps open at rest
there are more potassium channels open at rest
a cell membrane has ______ permiability
selective permiability
what 2 things together create a voltage gradient
concentration gradient & selective permiability
define voltage
electrical potential difference , measures how much electrical potential energy is strored between 2 points
define current
the rate electric change is flowing through something , the rate that ions are flowing out of a cell
what is the equation for voltage
current * resistance
if there is no concentration gradient is there voltage
no , both sides of a membrane will have the same concentration so there is no diffusion , therefore no voltage
if there is a concentration gradient is there voltage
yes
define elctrochemical equilibrium
the point where concentration gradient and electrical gradient cancel each other out
when there is electrochemical equilibrium is there net movment
no
define equilibrium potential
for every pair of intracellular/ extracellular ion concentrations there is one voltage that will give the state of electrochemical equilibrium
what is the nernst equation
if there is one permeant ion you can use the nernst equation to calculate the equilibrium potential
the concentration gradient is a form of what kind of energy
chemical energy
electrical gradient is a form of what kind of energy
electrical energy
what is the significance of studying the atlantic squid when studying membrane potential
the squid has a giant axon which allows us to study it
what 2 experiments can you do if you wanted to figure out what ion a squids axon membrane is permiable to .
- measure membrane potential and see if its close to any ions equilibrium potential
- change the ion concentration and see if there is an effect
when would when you use the goldman equation
the goldman equation takes into account the fact that the membrane is not equally permiable to all ions
define permiability
the ability of the membrane to let an ion through this is quatio to the number of ion channels open for an ion
ion channels are the same thing as ______
permiability
if you simplify the goldman equation what does it become
the nernst equation
true/false: the greater the concentration of particular ion and the less its membrane permiability , the greater its role in dermining the membrane potential
false : the greater the concentration of particular ion and the greater its membrane permiability the greater its role in dermining the membrane potential
if there is more than ion , but the permiability for one ion is exceptionally high , do we use the goldman or the nernst equation
the nernst
do we use relative or absolute permiabilites when dealing with ions
relative
in a nutshell what causes a membrane potential
concentraion gradients of ions across a selectivel permeable membrane
what 2 equations can we use to calculate the membrane potential
nernst and goldman
what a neural cell membrane is at rest is it mostly permiable to sodium or potassium
potassium
t/f if the neuron is at rest , the resting membrane potential is the the equilibrium potential
true
t/f if the neuron is NOT at rest , the resting membrane potential is the the equilibrium potential
false, you would need to do an experiment to determine the equilibrium potential
how would you experimentally determine the equilibrium potential of your system
you create at voltage diffeence an then measure whether current (ions) are flowing
if the voltage is less than the diffuisonal force which way will ions move
to the right
if the voltage is more than the diffusional force which way will ions move
to the left
if the voltage equals the diffusional force what will the current be
it will be zero
define reversal potential
where the sign of the current reverses from postive to negative
reversal potential is also known as _______ potential
equilibrium potential
when a neuron starts firing what occurs?
an electrical signal goes off so the membrane potential changes
define action potential
the characteristic pattern of membrane potential changes
the 1st phase of a electical signal in a neuron is called
the rising phase
list all of the stages in a neuron firing
- rising phase
- overshoot phase
- falling phase
- falling phase
- undershoot phase
the undershoot phase is also known as
hyperpolarization
hyperpolarization is an important contributor to …
aging , it contributes to learning and memory
what is hyperpolarization
making the membrane more negative
what is depolarization
making the membrane potential more positive
______ _______ involve temporary changes in membrane ______
action, potentials , potential
at rest nerual cell membranes seem to be mostly permeable to ___
potassium
t/f during an action potential an cell membrane greatly increases its permiability to potassium
false, sodium
