Transcript Module Two

How is the Nervous System
Organized?
Chapter 2-Neuroscience:
The Brain and Behavior
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Module Objectives:
Identify and define the structures of
the neuron
Identify and discuss the role of
neurotransmitters on behavior
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Ancient cultures believed the heart
was the center of all thoughts and
emotions. But we now know that the
brain and the rest of the nervous
system are the power behind our
psychological life and much of our
physical being.
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This chapter introduces you to
the field of neuroscience and
biopsychology
the scientific study of the biology
of behavior and mental processes
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This amazingly complex
nervous system controls some
of our most sophisticated
psychological behaviors
We will begin by examining the most
basic elements of the human nervous
system. Let’s look at our foundation!
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The Neuron
The neuron is the basic building
block of the nervous system
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Each one is a tiny information-processing
system with thousands of connections for
receiving and sending electrochemical
signals to other neurons.
Each human body may have as many as
one trillion neurons.
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Look at the following pictures
and make a list of words that
best describe the picture
Pretend that you’re describing the
picture to a friend who cannot see it.
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Did you notice a web-like
appearance in those neurons?
We will see that neurons do create a
neural network crucial to
communication…what you will also learn
is that as much as they look like a web,
neurons do not actually touch 1111
4 parts of the neuron
1.
Dendrites are specialized to receive
signals from neighboring neurons and
carry them back to the cell body
Thin, bushy-like structures that receive
information from outside the neuron
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Relays the information into the cell body
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The Neuron
2.
The Cell body
contains the
cell nucleus
The cell body
relays the
information
down to the
axon
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The structure of a neuron
3.
Axon: A thin, long structure that
transmits signals from the cell body to
the axon terminal.
Axon
4.
Axon Terminal is the last step for the
relay of information inside the
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neuron.
The cell body
is covered with
Axon
Terminals
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Once the information hits the
terminal, it is transmitted
outside the cell by
neurotransmitters, which reside
in the axon terminal.
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How do Neurons
Communicate?
-Electrical Communication
-Chemical Communication
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The Electrical Part
Action potential is an electrical current
sent down the axon.
The activity within the neurons is
electrical. This current causes the
neuron to “fire”
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This is an “all-or-none” process…a neuron
never firs half way. It either fires or it
doesn’t.
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Action potentials travel down the axon like
a wave of energy
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Synaptic transmission
The Synapse is the space between neurons
-The synaptic gap or cleft
Information must be transmitted across
the synapse to other neurons via the
neurotransmitters.
This is an electrochemical process
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Notice how the neurons don’t
physically touch
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Let’s Review!
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Presynaptic Neuron
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Neurotransmitters
Neurotransmitters are chemical
substances that reside in the axon
terminals
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They communicate to other neurons by
binding to receptors on neighboring
neurons
-The communication between neurons is
chemical
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Chemical Communication
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Synaptic Transmission
The neurotransmitters are released from
the vesicles and then attach to receptors
located on the postsynaptic neuron.
These neurotransmitters are in contact
with the dendrite of the postsynaptic
neuron only briefly.
‐ The chemical is almost immediately
destroyed or reabsorbed (reuptake)
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Neurotransmitters
At least 50 different types of
neurotransmitters have been identified
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Acetylcholine
GABA
Serotonin
Dopamine
Norepinephrine
Endorphins
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Acetylcholine
Activates motor neurons controlling
skeletal muscles
Contributes to the regulation of attention,
arousal and memory
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Examples of Neurotransmitters
Gamma-aminobutyric acid (GABA) is
involved in experiences of anxiety,
alcohol abuse, seizure disorders, and
sleep disorders
Serotonin is involved in sleep and
mood regulation, eating and aggression
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Abnormal levels may contribute to
depression and OCD
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Dopamine
Contributes to control of voluntary
movements, feelings of reward and
pleasure
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Too much dopamine has been associated with
schizophrenia
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Too little dopamine has been associated with
ADD and Parkinson’s Disease
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Norepinephrine
Involved in arousal reactions, especially
important for vigilance
‐ A heightened sensitivity to your
surroundings
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How do drugs effect
behavior?
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Drugs Impact on the Brain
Common drugs can alter the amount of a
neurotransmitter released at the synapses
Some drugs can mimic/facilitate the action of
the neurotransmitters while others can block
the action of the neurotransmitter.
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Agonists versus Antagonists
Agonists mimic or facilitate the actions of a
neurotransmitter
Antagonists oppose/block the actions of a
neurotransmitter
Agonist
Antagonist
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What’s Next?
The Brain
How do the neurons work together?
‐ The Central Nervous System
‐ The Peripheral Nervous System
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