Transcript between - physicsinfo.co.uk

Objectives
1.
Be able to state the meaning of the new
key words for this approach
2. Be able to describe the structure and
function of a motor neuron, a sensory
neuron and an interconnecting neuron.
3. Be able explain how electrical messages
are transmitted from one neuron to
another.
Label
Label
Write one sentence about what
the following features do
• Dendrite
Receives the nerve impulse or signal from adjacent neurons
• Axon
where the electrical signals pass along.
• Myelin sheath
Insulates /protects the axon from external influences that might effect
the transmission of the never impulse down the axon.
• Synaptic terminals
Terminal buttons send signals to an adjacent cell.
Neurotransmissions
• Dopamine
• http://www.youtube.com/watch?v=lCK2ua
uYkxE
Communication within neurons is
electrical
• Communication within neurons happens through
the process of conduction
• An electrical signal is sent down the length of the
axon. This electrical signal is called an “action
potential”
• Some axons are myelinated (i.e., covered with a
fatty tissue called the myelin sheath)—
myelinated axons allow for quicker transmission
of the electrical impulse.
Communication between neurons
is chemical
• When the electrical impulse reaches the terminal
buttons, they release chemicals called
neurotransmitters into the synapse.
• These neurotransmitters connect with receptor
sites (located mostly on the dendrites, but also
some on the soma) of nearby neurons. The
neurotransmitters “fit in” to these receptor sites
like locks into keys
Synapse between two neurons.
Label this Synapse
What you need to label:
1. Direction of impulse.
2. Axon
3. Synaptic vesicles
containing
neurotransmitter
4. Synaptic cleft
5. terminal button
6. Dendrite
7. Receptor site
Communication between neurons
is chemical
• In this “lock & key” fashion, neurotransmitters
unlock tiny channels at the receiving sites on
nearby neurons, and electrically charged atoms
enter the receiving neuron.
• These electrically charged atoms—through
altering the electrical charge of the receiving
neuron—either excite or inhibit its readiness to
fire an electrical impulse down it’s axon
Communication within neurons is
electrical
• Neurons fire when their electrical charge
reaches what is called the threshold of
excitation.
• When this threshold is reached, they send
an electrical charge or impulse down their
axons. This electrical impulse is called “an
action potential.”
Communication between neurons
is chemical and within neurons is
electrical…
• Through binding with receptor cells,
neurotransmitters alter the likelihood of the
receiving neurons reaching the threshold
of excitation, thus they are either inhibitory
(make the firing of the receiving neuron
LESS likely) or excitatory (make the firing
of the receiving neuron MORE likely).
Neurotransmitters…
• …are chemicals that are released into the
synapse by neurons.
• These neurotransmitters are “taken back
up” into the terminal buttons of neurons
through the process of reuptake
Label this Synapse
What do the following do:
1. Synaptic vesicles containing neurotransmitter
2. Synaptic cleft
3. terminal button
4. Dendrite
5. Receptor site
questions
1. What are Endorphins?
A collection of neurotransmitters that affect mood.
2. Name a drug that contains serotonin.
LSD
3. Which chemical affects voluntary movement?
Dopamine
4. These neurons receive messages from the outside world.
Sensory neurons
5. What do Motor Neurons do?
Carry nerve impulses from the CNS to the muscles
6. These neurons are located mostly in the brain.
Interneurons