Download Neurons and Neurotransmission with Nerve slides

NEURONS
&
NEUROTRANSMISSION
Neuron
•The basic building block of the
nervous system -- a nerve cell
•Neurons perform three basic tasks
•Receive information
•Carry the information
•Pass the information on to the next
neuron
Neurons
•Neurons “fire” -- send an impulse down
their length -- or they don’t “fire”
(all or none principle)
•Neurons come in a variety of shapes,
sizes, etc.
Neurons
Parts of the Neuron - Dendrites
Parts of the Neuron - Soma
Parts of the Neuron - Axon
Parts of the Neuron – Myelin Sheath
Parts of the Neuron – Axon Terminals
D= Dendrite
A = Axon
T= Terminal
In your row of three, the person closest to the window
explains what the dendrite does, the middle person
explains what the axon does, and the last person
explains the purpose of the axon terminal.
*** You have 10 seconds to send this message down
your row. ***
THE NEURAL
IMPULSE
Resting Potential
•The state of a neuron when it is at
rest and capable of generating an
action potential
•The neuron is set and ready to fire
Action Potential
•A brief electrical charge that
travels down the axon of the
neuron.
•Fire in an all-or-nothing manner
•When fired, and impulse is sent
and the neuron depolarizes.
Refractory Period
•The “recharging phase” when a
neuron, after firing, cannot
generate another action potential
(it is repolarizing)
•Once the refractory period is
complete the neuron can fire again
Urinal Demonstration – Lets
Go… Q upstairs boys restroom.
Neuron firing like a Toilet
1. Like a Neuron, a toilet has an action
potential. When you flush, an
“impulse” is sent down the sewer
pipe
Neuron firing like a Toilet
2. Like a neuron, a toilet has a refractory
period. There is a short delay after
flushing when the toilet cannot be
flushed again because the tank is
being refilled
Neuron firing like a Toilet
3. Like a Neuron, a toilet has a resting
potential. The toilet is “charged”
when there is water in the tank and it
is capable of being flushed again
Neuron firing like a Toilet
4. Like a Neuron, a toilet operates
on the all-or-none principle – it
always flushes with the same
intensity, no matter how much
force you apply to the handle
•Direction of impulse – neural impulse can only
go one direction; the toilet only flushes one
way, the impulse can’t come the other
direction (you hope!)
•Threshold – critical point after which neural
impulse is fired; you can push the handle a
little bit, but it won’t flush until you push the
handle past a certain critical point. This
corresponds to the level of excitatory
neurotransmitters that a neuron must absorb
before it will fire.
All-or-None Principle
•The principle that if a neuron fires it will
always fire at the same intensity
•All action potentials are of the same
strength.
•A neuron does NOT fire at 30%, 45% or
90% but at 100% each time it fires.
COMMUNICATION
BETWEEN
NEURONS
Synapse
•The tiny, fluid filled gap between the
axon terminal of one neuron and the
dendrite of another neuron
•The action potential cannot jump the
gap
Neurotransmitters
•A chemical messenger that travels
across the synapse from one neuron to
the next
•Can influence whether the second
neuron will generate an action potential
or not
Neurotransmitters
Excitatory Effect
•A neurotransmitter effect that makes it
more likely that the receiving neuron
will generate an action potential
(impulse)
•The second neuron is more likely to fire.
Inhibitory Effect
•A neurotransmitter effect that makes it
less likely that the receiving neuron will
generate an action potential (impulse)
•The second neuron is less likely to fire.
Receptor Cells
•Specialized cells in the sensory systems
of the body that can turn other kinds of
energy into action potentials that the
nervous system can process
•Receptor cells in the eye turn light into a
neural impulse the brain understands.
Show: Neural Communication video clip from anthology (1:45)
NERVES
Sensory Nerves
•Nerves that carry information to the
central nervous system
•Connect the sense organs to the brain
and spinal cord
Interneurons
•Nerve cells in the brain and spinal cord
responsible for processing information
related to sensory input and motor
output
Motor Nerves
•Nerves that carry information from the
central nervous system
•Carries messages from the brain and
spinal cord to other parts of your body
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain
A Neural Chain