Membrane Potential as Signals Flashcards
In general, what do changes in membrane potentials communicate information
communicate information
Changes in membrane potential are produced by: ______in ion concentrations in extracellular and intracellular _______. this is NOT involved in ______ transfer
alterations
fluid
information
Changes in membrane potential are produced by: changes in membrane ______ to an ion. this IS involved in _____ transfer. produces 2 types of signals:
permeability
information
graded and action potentials
Depolarization means what is inside the cell?
becoming less negative aka positive
more negative inside the cell means?
hyper polarization (below resting membrane potential)
repolarization means?
moving from a depolarization (more positive internal environment) back to a regular resting membrane potential
Graded potentials most often occur where?
the dendrites of cell bodies of neurons
where are chemically gated channels located?
the dendrites of cell bodies of neurons
graded potentials are referred to as graded because?
the magnitude varies directly with stimulus strength
are action potentials graded?
no
graded potentials are _______ lived ______ changes in membrane potential that don’t travel _____ _____
short-lived, localized
changes in polarization ______ in magnitude over distance
decrease
threshold stimulus or localized change is a
graded potential
In graded potentials: 1. a stimulus ________ small area of neurons membrane.
2. ions flow between the depolarized membrane area and the _______ areas.
Positive ions move ______ more negative areas.
Negative ions move ____ more positive areas
change is _____through leakage channels: this is why it does not go ____ ____
depolarizes polarised toward toward lost very far
Action potentials are the _____ method of communication between neurons
primary
Action potentials are a _____ reversal of _____ potential
brief, membrane
An action potential rises to ____ MV
+30
Action potentials occur in _____ _____ channels in cell ____and ____
voltage-gated
cell body, axon
Action potentials ____ _____ decrease in size with distance
do not
Action potentials can only occur in _______ and ______ cells
neurons and muscle cells
Action potentials require a ______ to be met
threshold
Action potentials are always the ______ ____ no matter what the size of the graded potential as long as it reaches a threshold.
same size (same magnitude)
Graded potentials are different in ________
magnitude
neurons send signals over long distances by generating and propagating ____ _____
action potentials
most action potentials generate in the _____ ____
of the initial _____. it then travels the _____ length of the axon
axon hillock
segment
enitire
during action potentials, ____ _____ channels open and close altering the ______ membrane.
a voltage stimulus changes the activation gates causing them to open.
permeability
repolarization restores resting ______ conditions in either side of the membrane
electrical
repolarization does ____ restore resting _____ conditions
not, ionic
what helps maintain ionic distributions during rest? (aka return concentrations after repolarization
sodium-potassium pumps
Propagation of action potentials are through 1. ________ ______. Depolarizing current flows to sext segment being it to threshold witch leads to regeneration of ____ _____ in a new region.
Voltage-gated NA+ inactivate and voltage-gated K+ open. _____ way propagation of nerve impulse
unmyelinated axons
action potential
one
myelinated axons are what type of conductions? _____ ______. these conductions are ___ ____ and action potentials are _____at each node. the spaces in between the myelinated sheaths on the axons are called _____ of ______ where action potentials are _______ due to the presence of ____ ____ Na+ channels. (mostly absent outside of nodes)
saltatory conduction very fast, regenerated nodes of Ranvier regenerated voltage-gated
action potentials are ____ or note
all
threshold - depolarization of ___-___mv from resting and requires more ____ entering the cell than K+ _____. This is affected by the strength of ____ graded potential (local current)
15-20
Na+
leaving
graded potentials ____ over time
degrade
strength of stimulus affects the magnitude of _____ potentials
graded
the weak stimulus will ______ before threshold can be reached
degrade
Absolute refractory period means
we have already generated/still occurring action potential
relative refractory period
no action potential occurs due to the cell being in the hyperpolarization stage. however, this requires a strong stimulus
hyperpolarization makes it harder for an action potential to propagate because?
are farther way from the threshold
why do stronger stimuli cause more frequent action potentials? what phase can this occur?
what refractory period is this?
we are not waiting for the membrane to return to baseline before then jumping again to the threshold
hyperpolarization phase
relative refractory period
Axon diameter: larger diameter axons means
faster impulse conduction
Axon diameter: has a larger degree of myelination:
a larger Degree of myelination: insulates and prevents _____ of charge.
leakage
