Transcript Chapter 2 - Biological Basis of Behavior

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Your body’s communication
network & control center
Peripheral Nervous System
(PNS)-gathers info from
inside & outside the body
Central Nervous System
(CNS)-receives info &
initiates responsecomposed of brain & spinal
cord
NEURONS = Messengers &
receivers of these
transmissions are
 Cell body-contains nucleus
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& cell membrane
Dendrites-branching
projections of the cell body,
carry impulses into the cell
Axon-Threadlike extension
carries impulses to & from
the cell, at the end of axon is
the axon terminal
Myelin Sheath-Insulates the
axon & speeds up
transmission of the
impulses
Synapse-point of contact at
which impulses are passed
from one cell to another
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Impulses passed via the brain
What is the chain of events that
happens from the instant you
hear the phone ring until you
pick up the phone?
Every time a stimulus—such as
a ringing telephone—is
detected, the body's neurons
send a nerve impulse through
the nervous system.
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If the safety of our body
requires a very quick
response, the signals may
pass directly to a motor
neuron for instant,
unthinking action. This is a
reflex action. Signals sent
via the spinal cord
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The nervous system helps information travel through your body. It
consists of the 5 senses, your brain, your spinal column, and
the nerves that connect them all together. Suppose your eyes see a
baseball sailing toward your head. They send a message about the
approaching ball to your brain. This message travels to a part of your
brain called the cerebrum through nerves. Your cerebrum sends this
information to the cerebellum, which has to choose whether to move
away, duck, or put a hand up to catch the ball. It finally decides that
you should catch it—after all, you’re wearing your baseball glove!
The cerebellum sends this decision as message through other nerves
to the arm and hand, activating the muscles used to catch the ball.
The time it takes from when your eye first notices the ball to when
your arm reaches up to catch it is an example of reaction time. Even
though stimuli—or changes in your environment that you react to—
travel very quickly along your nervous system as messages, your
body doesn’t react instantly. Many athletes spend hours practicing to
improve their reaction time. In this activity, you will conduct a
simple, measurable experiment (the ruler drop test) to study reaction
time and determine how it can be improved with practice.
Procedure
1. volunteer sits in a chair with good upright posture
2. places forearm so it extends over the edge of the table.
3. places thumb and index (pointer) finger on either side of the bottom of the
vertically placed ruler. The number “1” should be on the bottom, the “30”
near the top.
4.hold the ruler so that the bottom of the ruler is at a height of 2cm above
their fingers.
5.Tell your volunteer that you will release the ruler without telling them. Their
job will be to catch it with the thumb and forefinger as soon as they senses it
dropping.
6.Drop the ruler. When your volunteer catches it, record the number on the
ruler displayed just over their thumb. The lower the number, the faster their
reaction time.
7.Conduct several trials with the same volunteer.
8.Make sure to record the results for each trial in a table similar to the
following:
Volunteer cm trial 1 cm trial 2 cm trial 3 cm trial 4 cm trial 5
NAME
NAME
cm trial 6
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Share results:
When we begin to acquire a new physical skill
through repetition, our nervous system creates new
neural pathways. Here’s an example: when we
practice something like catching a ruler over and
over again, all the members of that neural pathway
(eye, brain, muscles) become more well-connected
and efficient. This phenomenon is often referred to
as muscle memory. However, no matter how good
your muscle memory for this task becomes, it will
always take some time for the falling ruler to travel
as a message from your eyes to your brain and from
your brain to your fingers!
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chemicals released by
vesicles in sending
neuron
travel across the
synapse and bind to
receptor sites on
receiving neuron
2 TYPES =
EXCITATORY = stimulate the brain, increase the likelihood that the
neuron will fire an action potential
INHIBITORY = calm the brain, balance mood & are depleted when
excitatory are overactive
Neurotransmitters bind to the receptors of the
receiving neuron in a “key-lock mechanism”.
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Serotonin
 various functions = body temp.,
sleep, mood, appetite, and pain
 Low levels =implicated in
depression & probs with
immune syst.
 Stimulant medications or
caffeine in your daily regimen
can cause a depletion of
serotonin
 High = Serotonin
Syndrome(mild to severe
symptoms including seizures)
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Norepinephrine (AKA
Noradreneline)
 Prepares you for action
 important for attentiveness,
emotions, sleeping, dreaming,
and learning
 causes blood vessels to contract
& heart rate to increase
GABA
 Gamma-Amino Butyric Acid
 An inhibitory neurotransmitter
 “nature’s VALIUM-like
substance”
 Related probs = anxiety,
seizures, Huntington’s disease
(nerve cell degeneration)
 Valium and similar antianxiety
drugs work at GABA synapses
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Dopamine
 main focus neurotransmitter
 Affects neurons associated with
voluntary movement
 role in learning, memory, and emotions
 Loss of dopamine-producing cells =
Parkinson’s Disease
 Excess = focusing issues, less
motivation, schizophrenia
 Stimulants (ex: cocaine, meds for
ADD/ADHD, caffeine) cause dopamine
to be pushed into the synapse so that
focus is improved
 BUT cause a depletion over time
Acetylcholine
 triggers muscle contraction
 important role in arousal and attention
 Loss = linked to Alzheimer’s Disease
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Endorphins
 linked to pain control and to
pleasure
 Reduce pain by inhibiting or
“turning down” neurons that
transmit pain information
 natural, opiate-like
neurotransmitters “morphine
within”
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 Dopamine pathways
are involved with
diseases such as
Parkinson’s disease
 caused by a
deterioration of brain
neuron’s that produce
dopamine (it is still
unknown why this
occurs)
Although not the sole cause of
schizophrenia, dopamine
unbalance is consistently
seen found in patients with
schizophrenia
Drugs that prevent dopamine
from binding to receptors can
reduce the symptoms of
schizophrenia
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Agonist
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Increases production
Activates the neuron
receptor that it
attaches to
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Antagonist
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Decreases production
Deactivates the
neuron receptor that
it attaches to
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Crash course Nervous System
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http://www.youtube.com/watch?v=x4PPZCLnVk
A
Crash Course “Your Chemical Brain”
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https://www.youtube.com/watch?v=W4N7AlzK7s