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Chapter 4
The Nervous System
© 2006 McGraw-Hill Higher Education. All rights reserved.
Homeostasis
© 2006 McGraw-Hill Higher Education. All rights reserved.
Figure 4.1
Every neuron has four regions: cell body, dendrites, axon, presynaptic
terminals.
© 2006 McGraw-Hill Higher Education. All rights reserved.
Neurotransmission
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All nervous systems consist of specialized
nerve cells called neurons
Neurons are responsible for receiving and
sending information
Sending and receiving information is a
highly specialized, precise and very rapid
© 2006 McGraw-Hill Higher Education. All rights reserved.
Neurotransmission

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The receiving region of the neuron is
affected by a chemical message that
either excites or inhibits
If the message is excitatory, an impulse
moves from the receiving region of the
neuron down the axon to the sending
region, the terminal, and chemical
messengers, neurotransmitters, are
released
© 2006 McGraw-Hill Higher Education. All rights reserved.
The Nervous Systems
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Somatic Nervous System
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The Autonomic Nervous System (ANS)
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Sensory information
Voluntary actions
Sympathetic
Parasympathetic
The Central Nervous System
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The Brain
Chemical Pathways
© 2006 McGraw-Hill Higher Education. All rights reserved.
Figure 4.3
© 2006 McGraw-Hill Higher Education. All rights reserved.
Figure 4.4
© 2006 McGraw-Hill Higher Education. All rights reserved.
Common Neurotransmitters
Neurotransmitter
type of effect
CNS changes
drugs of abuse
dopamine
inhibitoryexcitatory
amphetamines,
cocaine
GABA
inhibitory
serotonin
inhibitory
acetylcholine
excitatoryinhibitory
endorphins
inhibitory
euphoria
agitation
paranoia
sedation
relaxation
drowsiness
depression
sleep
relaxation
sedation
mild euphoria
excitation
insomnia
mild euphoria
block pain
slow respiration
© 2006 McGraw-Hill Higher Education. All rights reserved.
alcohol,
Valium-type
barbiturates
LSD
tobacco,
nicotine
narcotics
Figure 4.5
© 2006 McGraw-Hill Higher Education. All rights reserved.
Figure 4.6
Schematic representation of the
action of a synthetic enzyme. A
precursor molecule and another
chemical fragment both bind to
the enzyme. The fragment has
a tendency to connect with the
precursor, but the connection is
made much more likely
because of the way the enzyme
lines up to the two parts. After
the connection is made, the
new transmitter molecule
separates from the enzyme.
© 2006 McGraw-Hill Higher Education. All rights reserved.
Figure 4.7
© 2006 McGraw-Hill Higher Education. All rights reserved.
Figure 4.8
Schematic representation of
the action of a metabolic
enzyme. The transmitter
molecule binds to the enzyme
is such a way that the
transmitter molecule is
distorted and “pulled apart”.
The fragments then separate
from the enzyme.
© 2006 McGraw-Hill Higher Education. All rights reserved.
Chemical Theories of Behavior
The Chinese made the yin and the yang.
© 2006 McGraw-Hill Higher Education. All rights reserved.
Brain Imaging Techniques
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PET-Position Emission Tomography
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MRI- Magnetic Resonance Imaging
© 2006 McGraw-Hill Higher Education. All rights reserved.