Download The Nervous System

Chapter 1
The Physical Foundation
of Behavior
The Influence of DNA
• DNA: complex set of plans (genes)
stored in the nucleus of each cell
• Fraternal twins: develop from separate
fertilized eggs
• Identical twins: develop from one
fertilized egg and have identical DNA
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The Nervous System
• Neurons: the working cells of the nervous
system have three basic parts;
(See textbook Figure 1-2.)
– Cell body: bulk of the cell that contains the
nucleus and the cell machinery
– Dendrites: fibers that carry electrical
impulses to the cell body
– Axons: fibers that take electrical impulses
away from the cell body
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3
The Nervous System
• Tracts: long bundles of fibers that carry
electrical impulses inside of the central
nervous system
• Nerves: long bundles of fibers that carry
electrical impulses in the peripheral
nervous system
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4
The Nervous System
• Myelin sheath: a covering wrapped
around some nerve fibers that greatly
increases the speed of electrical impulses
(See textbook Figure 1-2.)
• Synapse: a specialized structure that
forms a junction between two neurons or
between a neuron and another type of cell
(See textbook Figure 1-4.)
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5
The Nervous System
• Neurotransmitters: chemicals that pass
an electrical impulse from one neuron to
another across a synapse
• Neuroinhibitors: chemicals that stop
electrical impulses from being passed from
one neuron to another across a synapse
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6
The Influence of the Environment
• Neurodevelopment: the growth and
organization of the nervous system
• Decisions: all connected neurons have
input into the decision a neuron makes
• Astrocytes: support cells in the brain and
spinal cord
• Domain: a group of neurons tied together
by one astrocyte
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7
Organization of the
Nervous System
• The Nervous System: is divided into
three primary divisions;
(See textbook Figure 1-6.)
– Sensory: neurons outside of the brain or
spinal cord extend fibers into the body to pick
up information
– Association: neurons in the brain receive
information from the sensory neurons,
process the input and make decisions
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Organization of the
Nervous System
– Motor division: motor neurons receive
impulses from association neurons and carry
them back to muscles,organs, and glands.
• Motor nervous system: is then divided
into two groups; (See textbook Figure 1-7.)
Somatic division
Autonomic division
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9
Organization of the
Nervous System
• Somatic: motor neurons that carry
electrical impulses to voluntary muscles
(muscle that can be moved at will)
• Autonomic: the division with motor
neurons that take impulses to glands and
to involuntary muscles in the heart,
organs, and blood vessels
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10
Organization of the
Nervous System
• Autonomic Nervous System: is
subdivided into two divisions:
– Sympathetic: motor neurons that move
things away from normal and is responsible
for “flight or fight” and stress reactions
– Parasympathetic: returns everything
back to normal
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11
The Brain
• Brain: encased in the skull, is the central
processing unit for the nervous system
and has four major divisions:
(See textbook Figure 1-8)
– Brain stem
– Diencephalon
– Cerebellum
– Cerebrum
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12
The Brain
• Brain stem: carries out processes vital to
the physical well being and survival of the
body; connects the rest of the brain to the
spinal cord
• Diencephalon: contains the thalamus and
the hypothalamus and is the major
switchboard of the brain
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13
The Brain
• Cerebellum: coordinates the activities of
voluntary muscles
• Cerebrum: largest part of the brain and
divided into right and left hemispheres.
Contains sensory and motor areas and is
the seat of higher mental functions. Has
centers that activate and inhibit behavior
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14
The Functional Brain
• Functional divisions: the functional
layers of the brain include
(See textbook Figure 1-10.)
– Brain stem
– Reptilian complex
– Limbic system
– Neocortex
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15
The Functional Brain
• Brain stem: most primitive part of the
brain; controls processes vital to physical
functioning of the body
• Reptilian complex: layer of brain over the
brain stem. The seat of status and
territory; enables more complicated
behaviors in life.
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16
The Functional Brain
• Limbic system: motivates and guides
group behavior; situated at the base of the
cerebrum; known as the emotional brain
• Neocortex: most complex development in
the brain; composed of the bulk of the
cerebrum. Responsible for higher mental
functions that we identify with being
human and humane.
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Consciousness
• Consciousness: a great mystery.
Awareness including self awareness
• Spirit: The origin of belief in a spirit is
unknown. Consciousness has been
equated as the Spirit within us. Belief is
widespread and the basis of most religion.
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Consciousness
• Chemical consciousness: scientific view.
Result of patterns and concentrations of
chemicals in the brain
• Quantum consciousness: emerging
view. Based in quantum waves isolated in
the neurons of the brain; contains
elements of spiritual and chemical
consciousness
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Consciousness
• Void: Mathematics is the only language
that describes the void.
• Quantum computers have the potential
to be more powerful than a conventional
computer. Still rudimentary, they open the
possibility that consciousness may be a
quantum phenomenon
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20
Metaphysics
• Metaphysics: reality and rules beyond the
limits of the universe and understanding.
Recognized and identified by
– Science: as an existence and a power which
creates and sustains the universe
– Religion: as an existence and power Who
creates and sustains the universe
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Summary
• DNA is the genetic material received from
our parents
• At birth the brain is about 15% developed
• Growth of the brain is a long and complex
process which requires both genetic plans
and interactions with the environment
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22
Summary
• The brain is divided both structurally and
functionally and each area is responsible
for its own tasks
• The most complex achievement of the
brain is consciousness
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