Download Neurons, Hormones, and the Brain

Neurons, Hormones, and
the Brain
©2002 Prentice Hall
Neurons, Hormones, and the
Brain
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The Nervous System: A Basic Blueprint
Communication in the Nervous System
Mapping the Brain
A Tour Through the Brain
The Two Hemispheres of the Brain
Two Stubborn Issues in Brain Research
©2002 Prentice Hall
Communication in the
Nervous System
The Structure of the Neuron
How Neurons Communicate
Chemical Messengers in the
Nervous System
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The Structure of the Neuron
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Dendrite: Branches
that receive signals
and transmit to cell
body
Soma: Controls cell
metabolism and
determines firing
Axon: Carries
impulses away from
cell body
Myelin Sheath: Fatty
insulation
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Different Kinds of Neurons
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Neurons vary in size and shape, depending on
their location and function. More than 200 types
have been identified in mammals.
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How Neurons Communicate
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Synapse: Tiny fluid filled gap between the
axon terminal of one neuron and the dendrite
of another.
Neurotransmitter: Chemical that travels
across the synapse from one neuron to the
next.
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How Neurons Communicate
Receptor
Cells
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Action
Potential
Sensory
Nerves
Interneurons
Travel to
Brain
The receptor cells turn information into an impulse
Send the impulse along the sensory nerve to the brain
Interneurons Process the information
Motor nerves carry out the action associated with the senstation
©2002 Prentice Hall
Plasticity in Brain & Behavior
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Does experience really
make us smarter and
more well rounded?
Homework: Read the
case study handed out
in class.
Answer discussion
questions for
homework!
©2002 Prentice Hall
Getting Connected
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Neurons in a newborn’s brain are widely spaced,
but form connections quickly.
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Chemical Messengers in the
Nervous System
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Neurotransmitters are
released into synaptic
cleft
Binds to receptor site
Receiving neuron
becomes more (or less)
likely to fire
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Major Neurotransmitters
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Acetylcholine (ACh)
Dopamine
Serotonin
Norepinephrine
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Endorphins
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Chemical substances in the nervous system
that are involved in pain reduction, pleasure,
and memory, and are known technically as
endogenous opioid peptides.
©2002 Prentice Hall
The Nervous System:
A Basic Blueprint
The Central Nervous System
The Peripheral Nervous System
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Divisions of the Nervous System
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Central Nervous System
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Brain
Spinal cord
Peripheral Nervous
System
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Somatic
Autonomic
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Nervous System Organization
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The Central Nervous System
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Central Nervous System: The portion of the
nervous system consisting of the brain and
spinal cord.
Spinal Cord: A collection of neurons and
tissue running from the base of the brain
down the back, protected the spinal column.
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The Peripheral Nervous
System
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Somatic Nervous System: The subdivision
of the PNS that connects to sensory
receptors and to muscles
Autonomic Nervous System: The
subdivision of the PNS that regulates the
internal organs and glands.
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Hormones
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Hormones: Chemical substances, secreted
by organs called glands, that affect the
functioning of other organs.
Endocrine Glands: Internal organs that
produce hormones and release them into the
bloodstream.
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The Endocrine System
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Hypothalamus
Pituitary
Thyroid
Adrenal
Pancreas
Ovary
Testis
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Mapping the Brain
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Electroencephalogram
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Positron Emission
Tomography
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Active areas have
increased blood flow
Radioactive isotopes
(small amounts) are
placed in the blood
Sensors detect
radioactivity
Different tasks show
distinct activity patterns
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Magnetic Resonance Imaging
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Magnetic fields align
certain ions and
compounds
When field is removed,
these molecules release
energy as radio waves
Computer calculates
tissue density from radio
waves
Provides clear, 3D
images
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A Tour Through the Brain
The Brain Stem
The Cerebellum
The Thalamus
The Hypothalamus and the Pituitary Gland
The Limbic System
The Cerebrum
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The Human Brain
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This view shows
the brain as if split
in half front-toback
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Inside surface of
right half of brain
Eyes on the left,
near the word
“hypothalamus”
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The Brain Stem
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Brain Stem: At the top of the
spinal cord, consisting of medulla
and pons
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Medulla: Responsible for some
automatic functions,
Pons: Involved in sleep, waking, and
dreaming.
Reticular Formation: A dense
network of neurons found in the core
of the brain stem.
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The Cerebellum
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Cerebellum: Regulates movement and
balance, and is involved in learning some
simple responses.
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Thalamus and Hypothalamus
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Thalamus: Relays sensory
messages to the cerebral cortex.
Hypothalamus: Involved in emotions
and drives vital to survival; it
regulates the autonomic nervous
system.
Pituitary Gland: Small endocrine
gland at the base of the brain, which
releases hormones and regulates
endocrine glands.
©2002 Prentice Hall
The Limbic System
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Limbic System: A group of
brain areas involved in
emotional reactions and
motivated behavior.
Amygdala: Involved in the
regulation of emotion and the
initial response to sensory
information.
Hippocampus: Involved in
memory.
©2002 Prentice Hall
The Cerebrum
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Occipital Lobes: Vision
Parietal Lobes: body
sensation
Temporal Lobes:
Hearing, language
Frontal Lobes:
Thinking, planning,
movement
©2002 Prentice Hall
The Case of Phineas Gage
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Gage was a railroad
construction foreman
An 1848 explosion
forced a steel tamping
rod through his head
Others said he was
“…no longer Gage…”
Lost his job, worked as
a sideshow exhibit
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The Two Hemispheres
of the Brain
Split Brains: A House Divided
A Question of Dominance
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Visual Pathways
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Each hemisphere
receives information
about the opposite side
of the visual field.
Objects to your left put
images on right side of
each retina; goes to
right side of brain
Half of optic nerve fibers
cross at the optic
chiasm
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Split Brains: A House Divided
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Hemispheres of brain sometimes separated
to treat severe epilepsy
Split brain operation includes the optic
chiasm
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Optic nerve no longer crosses
Visual information goes only to one hemisphere
Different sides of brain see different
information
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Divided Brain, Divided View
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Two Stubborn Issues
in Brain Research
Why Do We Dream?
Are There “His” and “Hers”
Brains?
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Why Do We Dream?
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Rapid Eye Movement (REM) Sleep: Sleep
periods characterized by fast eye
movement behind closed eyelids, loss of
muscle tone, and dreaming.
Activation-Synthesis Theory: Theory that
dreaming results from cortical synthesis
and interpretation of neural signals
triggered by activity in the lower part of the
brain.
©2002 Prentice Hall
Are There “His” & “Hers” Brains?
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Sex differences in the brain have
been studied for many years.
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Many findings seem to reflect
cultural bias, and change with
cultural changes
Reliable differences have been
found in activity of certain brain
areas during some tasks
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Example: MRI of language task, right
©2002 Prentice Hall
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