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Biopsychology
Mind-Body Connection
Most experts in the field of psychology and
biology agree that the mind and body are
connected in more complex ways than we can
ever comprehend.
 Research constantly shows us that the way we
think affects our behavior, feelings, and our
body’s response.
 The opposite is also true – physical illness,
physical exhilaration, exercising, insomnia,
among other physical activities affect the way
we feel and behave, but also the way we think
about ourselves and the world.

Mind-Body Connection

Since most of this online class is devoted
to the way our mind works (as opposed
to our biology), this chapter will focus on
the neuron, the nervous system, and how
these physiological components of our
being interact, respond to, and influence
our psychological health.
Neuron
The neuron is the basic building block of
the nervous system, which is the body’s
primary communication network.
 The nervous system gathers and
processes information from the
environment and allows you to act on the
environment.
 The neuron’s basic task is to
communicate with in and with other
neurons.

The Neuron
Neuron
Neurons vary greatly in size and shape,
depending on their specialized function:
-Human brain  100 billion neurons
-brain tissue  rice grain -10,000 neurons
 Neurons are simple “cheap” structures, but
highly specialized.

Neuron

The neuron is comprised of three basic
components:
◦ Dendrites
◦ Cell body or soma
◦ Axon
Dendrites
Dentrites receive information from other neurons
 In Greek, dendrites mean branches, hence, they are
like extensive tree branches.
 The more branches, the more information a neuron
can receive.

Soma or Cell Body
The soma, or more commonly referred to as
the cell body, sums and subtracts the
information it receives from the dendrites.
 It also contains the nucleus, which provides
energy for neurons to carry out their function.

Stimulus threshold
In order for a neuron to fire it’s message, it
must reach “stimulus threshold.”
 Stimulus threshold is the minimum amount of
information needed for the neuron to fire.
 For example, your friend is talking in a low
voice, so low that you don’t even hear it.
Stimulus threshold is the lowest your friend can
talk to you so that you actually pick up the
sound, which is why the definition states that it
is the minimum amount of information.

The Axon
The Axon sends messages to other neurons
and parts of body (ie. glands, muscles).
 Unlike the dendrites, there is only one axon,
which varies in length (few thousandths of
inch to base of spine to big toe).

Action Potential
The firing of the message down the axon
is called “action potential.”
 It occurs in an “all-or-none” process,
which means either the message is sent
or not sent.
 For example: imagine dominos are lined
up perfectly, if you tap the first domino,
they either all fall down or none of them
fall down.

Action Potential
Let’s go back to the example of your
friend whispering.
 The louder your friend talks to you, the
faster the action potential (or message)
will be sent to the appropriate brain
region so that it can process this auditory
information.

Myelin Sheath
To help transmit the message or action
potential down the axon, “myelin sheath”
insulates the axon.
 Myelinated axons speed neuronal transmission
by about 15 times.
 Most neurons are myelinated, however, not all.

Myelin Sheath
Myelinated axons are responsible for
making our bodily movements smooth.
 If myelinated axons start to degenerate,
then degenerative diseases, such as multiple
sclerosis or Parkinson’s disease occurs,
where movement is much more jagged.

Axon Terminals
At the end of the axon are axon terminals
or terminal buttons.
 They contain neurotransmitters.

Neurotransmitters
Neurotransmitters are chemical messengers that
cross the small space between two neurons called
the synapse.
 Then the neurotransmitters attach to receptor
sites (on the dendrites) of the surrounding
neurons.
 These are the chemicals in the brain that doctors
often refer to people with mental illnesses as
having “chemical imbalances.”
 What they are essentially saying is that there is
either too much or too little of a particular
chemical or neurotransmitter needed for optimal
health.

Here are close-up pictures of the
action potential traveling down the
axon to the axon terminals (pic. a),
releasing the neurotransmitters
across the synapse (pic. b), to
connect onto receptor sites of other
neurons (pic. c).
Neurotransmitter molecules have specific shapes; Receptor
molecules have binding sites and must fit together like a
“lock-and-key.”
One example of a neurotransmitter is
serotonin.
Serotonin is responsible for sleep, moods,
and emotional states.
 Too much serotonin in the system may
cause Autism and too little may cause
anxiety and mood disorders.

Conclusion
We can use our bodies as maps as to what is
going on for us physically, psychologically, and
emotionally.
 When the body experiences stress, the
system can become imbalanced.
 Western medicine uses medication to help
restore balance.
 As students of psychology, it is also
important to process our emotions, heal our
past, and become aware of our thoughts to
experience the most profound and holistic
changes possible.
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