293733
Description
Mind Map by lynda_ashford_25, updated more than 1 year ago
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Created by lynda_ashford_25
over 10 years ago
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Electrochemical Characteristics of Neurons
- Neuronal membrane-
all parts of a neuron are
covered by a membrane
about 8nm thick. Has
two layers of
phospholipid molecules
- Electrical gradient-
membrane remains
this when there is no
outside disturbance.
Has a negatively
charged inside due to
negative proteins.
- Polarization- difference
of electrical charge
between the inside and
outside of the cell.
- Concentration gradient-
the difference in
distribution of ions across
the membrane
- Sodium is more
concentrated outside
than inside. More likely
to enter cell than leave
it.
- Sodium is more
concentrated outside
than inside. More likely
to enter cell than leave
it.
- Polarization- difference
of electrical charge
between the inside and
outside of the cell.
- Electrical gradient-
membrane remains
this when there is no
outside disturbance.
Has a negatively
charged inside due to
negative proteins.
- Resting potential- prepares a
neuron to respond rapidly.
Maintains the negative charge
within the neuron by the
sodium-potassium pump.
- Sodium-potassium pump-
every two potassium ions it
draws into a cell, it removes
three sodium cells.
- Sodium-potassium pump-
every two potassium ions it
draws into a cell, it removes
three sodium cells.
- Action potential- messages
sent by the axon. Achieved
when the sodium channels
open. If enough sodium gets
in via depolarization, it can
reach the threshold of
excitation causing sodium
channels to open.
- A positive charge now
flows down the axon and
opens channel at the next
point, the Nodes of Ranvier,
which over shoots the
charge.
- Channels then snap
shut and the
sodium-potassium
pump helps return
the cell to a
polarized level.
- Leads to an undershoot
phase as potassium rushes
out of its channels due to the
new positive charge. Known
as hyperpolarization
- Leads to an undershoot
phase as potassium rushes
out of its channels due to the
new positive charge. Known
as hyperpolarization
- Propagation of the action
potential- transmission of
action potential down an
axon (gives birth to a new
action potential at each
point along the axon)
- All or none law- the
amplitude and velocity of
an action potential are
independent of the
intensity of the stimuli that
initiated it. A stronger
stimulus does not produce
a stronger action potential
- Channels then snap
shut and the
sodium-potassium
pump helps return
the cell to a
polarized level.
- A positive charge now
flows down the axon and
opens channel at the next
point, the Nodes of Ranvier,
which over shoots the
charge.
- Refractory period-
cell resists the
production of further
action potentials
- Absolute refractory-
first stage that lasts
about 1ms.
Membrane cannot
produce an action
potential.
- Relative refractory-
second stage that
lasts about 2-4ms.
Action potential can
be produced but only
by a stronger than
usual stimulus
- Relative refractory-
second stage that
lasts about 2-4ms.
Action potential can
be produced but only
by a stronger than
usual stimulus
- Absolute refractory-
first stage that lasts
about 1ms.
Membrane cannot
produce an action
potential.
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