Transcript Using POCS Method of Problem

Chapter 2: Biological Foundations of Behavior
Michael L. Farris
Psychology 101
Nervous System
Autonomic nervous system - The division of the nervous system that
regulates the body’s inner environment (heart rate, blood pressure,
digestion, pupil dilation, and electrical conductance of the skin.) Pgs.
50-51.
Afferent Nerves: (advance, arrive, approach) carry sensory signals from
internal organs TO the CNS (brain and spinal cord). Up. p.40.
Efferent nerves (Exit, Embark, Escape p. 52) carry motor signals away
from the central nervous system TO the skeletal muscles. Down.
P.41.
Afferent and efferent nerves are also known as sensory neurons (p. 40).
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The Blood-Brain Barrier
Blood-Brain Barrier: (Pinel, p. 55) The brain is
a finely tuned electrochemical organ whose
function can be severely disturbed by the
introduction of certain kinds of chemicals.
Fortunately, there is a mechanism that impedes
the passage of many toxic substances from
the blood into the brain; the blood-brain
barrier.
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The Brain Stem
Brain Stem: The part of the brain on which the
cerebral hemispheres rest; in general, it regulates
reflex activities that are critical for survival (heart
rate and respiration). The Brain Stem
(particularly the medulla) regulates basic life
functions (heart rate and breathing, and such
reflexes as swallowing, coughing, and
sneezing). P. 53.
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Cerebral Hemispheres, Corpus Callosum

The brain is composed of two sides, or hemispheres.

Left Brain: Controls language, speech, writing, calculation, time
sense, rhythm, and the ordering of complex movements.

Right Brain: Non-verbal. Controls perceptual skills, visualization,
recognition of patterns, faces, and melodies, recognition and
expression of emotion, spatial skills, and simple language
comprehension.

The left and right hemispheres are joined together by the Corpus
Callosum, a structure in the middle of the brain that enables
hemispheres to share functions and information.

Please see pages 54-54 in your text for more information.
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Case Studies
Studies that focus on a single case or subject.
 Detailed
 In-depth
 Pro: Good source of testable hypotheses.
 Con: not very easy to generalize to others.
Humans differ; be skeptical of any biopsychological
theory based on only a few case studies. P.23.
Example: Lobotomy (1 primate study)
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CNS and Cerebral Cortex
Central Nervous System (CNS): The portion of the
nervous system within the skull and spine.
Composed of 2 divisions: Brain and Spinal Cord.
Cerebral Cortex - The layer of neural tissue
covering the cerebral hemispheres of humans and
other mammals. Being the OUTER layer, it is
most likely to be damaged by accident or
surgery.
Please see pages 47-50 for more information.
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Thinking and Learning
Cerebrum - The portion of the brain that
sits on the brain stem; in general, it plays a
role in complex adaptive processes (like
learning, perception, and motivation). P.54.
Cognition - Complex intellectual processes
such as thought, memory, attention, and
perceptual processing. p.11.
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Comparative Psychology
Comparative Psychology - The division
of Biopsychology that studies the
evolution, genetics, and adaptiveness of
behavior, often by using the comparative
method (The study of biological
processes by comparison of different
species). P.15.
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Convolutions



Folds on the surface of the cerebral
hemispheres.
Folds have increased over time
greatly increased the volume of the
cerebral cortex (the outermost layer of
cerebral tissue).
More surface area = more capacity
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DNA, EEG, and Evolution
Deoxyribonucleic acid (DNA) Double Stranded,
coiled molecules of genetic material. The basic
chemical material in chromosomes that carries
the individual’s genetic code. (p.72).
Electroencephalograph (EEG) - A measure of the
general electrical activity of the brain, often
recorded through the scalp. Pgs. 58-59.
Evolve - To undergo gradual orderly change. P.10.
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Myelin
 Myelinated Nerves carry signals 200 times FASTER than
unmyelinated ones.
 (Axons vary in length from 0.04 inches to 1 yard.)
 The fastest nerve signals travel at over 250 mph.
 Nerve signals enter a neuron through its dendrites and rush along
the axon. At the far end, called the nerve-ending, the axon has other
dendrites that pass the message on to the dendrites of other neurons.
 Neurons that have to carry urgent signals over long distances are
surrounded by thick insulation to keep the signal strong, in the same
way that the cable from a TV aerial to the TV is coated with insulating
plastic.
 In the case of neurons, the insulation is a myelin sheath—a series
of long, flat cells wrapped around the axon. In people with the
crippling disease multiple sclerosis, the sheaths break down,
weakening the nerve signals. Pgs. 41-42.
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Natural Selection
Heritable traits that are associated with high rates of
survival and reproduction are preferentially passed on to
future generations. (No magic here; simply good traits get
reproduced.)
For example, fast horses are selected and bred by
racehorse breeders, so each succeeding generation gets
faster overall. The slow ones don’t get a chance to
reproduce and pass on their slower genes. Nature is
similar. The slow fish can’t outrun the shark, so doesn’t get
to reproduce.
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Nature/Nurture and PNS
Nature-nurture issue - The debate about the relative
contributions of nature (genes) and nurture
(experience) to the behavioral capacities of
individuals. Pgs. 72-73.
Peripheral Nervous System (PNS): The division
located outside the skull and spine. Composed of 2
divisions:
1. Somatic nervous system (SNS) (the part of the PNS
that interacts with the external environment)
2. Autonomic nervous system (ANS), the part which
participates in the regulation of the internal
environment. Pgs. 47-49.
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Lobotomy and Spinal Cord
Prefrontal Lobes - The large areas, left and right, at the
very front of the brain.
Prefrontal Lobotomy - A surgical procedure in which the
connections between the prefrontal lobes and the rest
of the brain are cut as a treatment for mental illness.
Spinal Cord comprises 2 different areas:
1. Gray Matter (composed largely of cell bodies and
unmyelinated interneurons)
2. White Matter (composed largely of myelinated
axons.) It is the myelin that gives the white matter
its glossy white sheen.
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Sympathetic and Parasympathetic
Nerves

Sympathetic nerves stimulate, organize, and
mobilize energy resources in threatening situations.
Sympathetic changes are indicative of psychological
arousal.

Parasympathetic nerves act to conserve energy.
Parasympathetic changes are indicative of
psychological relaxation (think of a parachute).

Each autonomic target organ receives opposing
sympathetic and parasympathetic input, and its
activity is thus controlled by relative levels of
sympathetic and parasympathetic activity. P.51.
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Brain Anatomy
Early brain development: 3 sections form (forebrain,
midbrain, and hindbrain).
Later, these grow into five major different swellings
(telencephalon, diencephalons, mesencephalon
(midbrain), metencephalon, and myelencephalon).
ENCEPHALON means within the head. In humans,
the telencephalon (right and left cerebral
hemispheres) undergo the greatest growth during
development.
The other 4 divisions are often referred to
collectively as the Brain Stem, on which the
cerebral hemispheres sit. The myelencephalon is
often referred to as the medulla.
Again: Brain Stem = myelencephalon,
metencephalon, mesencephalon, and
diencephalon. 4 of 5 divisions are in the stem.
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Brain and Spine Protectors
Meninges, Ventricles, and Cerebrospinal Fluid (Pinel p. 53):
The brain and spinal cord (the CNS) are the most protected
organs in the body. They are encased in bone and covered by
three protective membranes, the meninges.
Also protecting the CNS is cerebrospinal fluid, which fills the
central canal of the spinal cord and the cerebral ventricles of the
brain. It also fills the subarachnoid space, which contains many
large blood vessels.
The cerebral ventricles are the four large internal chambers
of the brain: 2 lateral ventricles, the third ventricle, and the fourth
ventricle. It is believed that the ventricles are often enlarged in
people with schizophrenia.
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Neural Conduction and Synaptic Transmission
Neural Conduction=Electrical (the way a
nerve impulse travels along a nerve cell.
Synaptic Transmission=Chemical (the way
neurotransmitters travel across the synapse
(gap) to communicate with another nerve cell
(neuron).
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Neural Conduction/Synaptic Transmission
Nerve signals are constantly whizzing from neuron to neuron all
around your body – yet no two neurons ever actually touch.
Instead, there is a small gap between connecting neurons
called a synapse.
When a nerve signal is passed on from one neuron to the next, it is
carried across the gap by special chemicals called
neurotransmitters. The chemicals are released by the neuron
that is sending the signal.
Droplets of neurotransmitters are stored inside the nerve-ending in
tiny sacs called vesicles. When a nerve signal arrives at the
nerve-ending, the vesicles drift towards the synapse and spill
out their contents into the gap. The neurotransmitters flood
across the gap and wash up against the other nerve. Inside
every nerve ending are sacs of chemical transmitters. These
are released into the synapse when the nerve is activated, or
“excited”, by a nerve signal. If the adjoining nerve has the right
receptors (page 95), the signal will pass on.
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Neural Conduction and Synaptic Transmission




The term exocytosis (Pinel pages 94-95) refers to
the process of releasing a neurotransmitter.
Neurotransmitter chemicals work a bit like keys in
locks. In this case, the “locks” are special receptor
sites in the dendrites of the receiving neuron.
These sites accept only one kind of chemical. For
the nerve signal to pass on, the neurotransmitter
must be the right chemical that fits, or “unlocks”, the
receptor site. If the neurotransmitter fits, it changes
the chemistry of the receiving nerve’s membrane
(skin). This starts off the electrical charges that pass
the signal along the length of the neuron.
Because a receptor site responds only to one type
of neurotransmitter, an active nerve will pass on the
signal only to neurons that have the right receptors,21
even though it is linked to many others. Pgs.40,43-44.
Excitation and Inhibition

Different types of signals follow different
routes through the body.

If every single nerve signal were passed
on by every single synapse, you would
simply be overwhelmed by nerve signals.
This is why at some synapses the receiving
neurons react by passing on the signal, but at
others they react by blocking it.

This is called excitation and inhibition.
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Neurotransmitters
 There are more than 40 different neurotransmitters
 Noradrenaline helps to control heartbeat and blood flow
 Dopamine works in the areas of the brain that control
movement and coordination (when you’re making a tricky
move on a skateboard, your nerve endings are releasing lots
of dopamine, a neurotransmitter that helps muscles move
more easily).
 Endorphins are used by the brain to control pain (they are
called “endogenous opiates”—literally, opiumlike chemicals
that are produced within the body; see page 100 for more
information).
 Acetylcholine is involved in making muscles contract
 When you wake up in the morning, it is because certain
nerves are flooding your brain with the neurotransmitter
serotonin—and any nerve that is receptive gets an alarm
call!
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