Download a positive electrical signal

Afferent Nerves
Efferent Nerves
dendrites: branches that receive chemical signals
& convert them into electrical signals
cell body: central part of cell;
contains the nucleus
axon terminals: branching ends;
receives electrical signals and releases
chemical signals out of the neuron
axon: long slender extension from cell body;
used to transmit electrical signals
Dendrites receive an incoming signal
Synapse: the gap
between neurons
The signals travels along
the length of the neuron
The axon terminals of the pre-synaptic cell
deliver the signal to the post-synaptic cell
RESTING POTENTIAL
A neuron is typically
at -70mV
ACTION POTENTIAL
a positive electrical signal
at +35mV
-70 mV
Voltage (mV)
RESTING POTENTIAL
time
RESTING POTENTIAL
A transport protein forces ions against
their concentration gradients
3 sodium (Na+)
molecules
are pushed
outside the cell
2 Potassium
(K+) molecules
are pushed
inside the cell
There is a net removal of positive ions (cations)
outside the cell; inside of the cell becomes negative
ACTION POTENTIAL
-70 mV
Voltage (mV)
DEPOLARIZATION
the inside of the cell
changes from -70mV to
+35mV
time
NEUROTRANSMITTERS: chemical signals sent from the
axon terminals of the pre-synaptic cell through exocytosis
that bind receptors on the dendrites of the post-synaptic cell
DEPOLARIZATION
The binding of neurotransmitters to
the receptors of dendrites triggers
the opening of a few Na+ channels
This causes a slightly positive charge
When the charge reaches the
threshold (-55mV), many voltagecontrolled Na+ channels open,
causing a flood of positive charges
All-or-None Principle
ACTION POTENTIAL
-70 mV
Voltage (mV)
REPOLARIZATION
the cell returns to
resting potential;
time
often overshoots this
return
REPOLARIZATION
As Na+ channels close,
K + gates open.
K + rushes out of the cell, returning
to the cell to a -70mV resting
potential
As the action potential reaches the axon terminal,
neurotransmitters are exocytosed from the neuron and bind to
receptors on the next neuron
https://www.youtube.com/watch?v=SdUUP2pMmQ4
Select one of the following neurotransmitters and be
prepared to share its role with the class
Acetylcholine
Dopamine
Norepinephrine & Epinephrine
Serotonin
Histamine