Download The World of Psychology

The Biology of Behavior
Book authors:
E.H. Ettinger
Chapter 3
The Biology of
Behavior
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Neurons and the
Neurotransmitters
 Neuron
– A specialized cell that conducts impulses through
the nervous system and contains three major partsa cell body, dendrites, and an axon
– Afferent neurons relay messages from the sense
organs and receptors—eyes, ears, nose, mouth,
and skin—to the brain or spinal cord
– Efferent neurons convey signals from the central
nervous system to the glands and the muscles,
enabling the body to move
– Interneurons carry information between neurons in
the brain and between neurons in the spinal cord
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Neurons and the
Neurotransmitters
Anatomy of a Neuron
– Cell body
 The part of the neuron that contains the nucleus and
carries out the neuron’s metabolic functions
– Dendrites
 The branchlike extensions of a neuron that receive signals
from other neurons
– Axon
 The slender, tail-like extension of the neuron that transmits
signals to the dendrites or cell body of the other neurons or
to muscles or glands
– Synapse
 The junction where the axon of a sending neuron
communicates with a receiving neuron across the synaptic
cleft
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Neurons and the
Neurotransmitters
Anatomy of a Neuron
– Glia Cells
 Cells that help to make the brain more efficient by holding
neurons together, removing waste products such as dead
neurons, making the myelin coating for the axons, and
performing other manufacturing, nourishing, and cleanup
tasks
– Mylin Sheath
 Insulating covers around some axons that increases
neuron’s ability to conduct electrical impulses. Loss of
mylin is Multiple Sclerosis
– Nodes of Ranvier
 Small gap or exposed portion of an axon between mylin
covers.
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Neurons and the
Neurotransmitters
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Neurons and the
Neurotransmitters
 Sodium-Potassium Pump
– The penetration and removal of sodium (Na+) and potassium
(K+) through the cell membrane allows for the transmission of
the action potential down the axon of the neuron without
electrical energy loss.
 Permeability
– The capability of being penetrated or passed through
 Resting potential
– The membrane potential of a neuron at rest, about -55 millivolts
 Action potential
– The sudden reversal of the resting potential, which initiates the
firing of a neuron
– Complete process takes about 1 millisecond (1/1,000) of a
second
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Neurons and the
Neurotransmitters
Na+
Na+ & K+
Cl- & K+
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Neurons and the
Neurotransmitters
 Action of
Neurotransmitters
– Excitatory Postsynaptic Potentials
 EPSPs
 Influencing surrounding neurons
to fire
– Inhibitory Postsynaptic Potentials
 IPSPs
 Influencing surrounding neurons
not to fire
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Neurons and the
Neurotransmitters
 Neurotransmitters
– A chemical that is released into the synaptic cleft
from the axon terminal of a sending neuron, crosses
a synapse, and binds to appropriate receptor sites
on the dendrites or cell body of a receiving neuron,
influencing the cell either to fire or not to fire
 Receptors
– Protein molecules on the dendrite or cell body of a
neuron that will interact only with specific
neurotransmitters
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Neurons and the
Neurotransmitters
 How synaptic vesicles can continually pour out
neurotransmitters
– Cell body of the neuron is always working to manufacture
more of the neurotransmitter substance
– Unused neurotransmitters in the synaptic cleft may be broken
down into their component molecules and reclaimed by the
axon terminal to be recycled and used again
– Reuptake
 The process by which neurotransmitter molecules are
taken from the synaptic cleft back into the axon terminal for
later use, thus terminating their excitatory or inhibitory
effect on the receiving neuron
– Breakdown
 Neurotransmitter molecules that are not taken back up into the
axon terminal are metabolized into waste products.
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Neurons and the
Neurotransmitters
 Neurotransmitters called monoamines
– Acetylcholine
 Excitatory neurotransmitter in the brain but may be
excitatory or inhibitory in organs of PNS. Involved in
learning, movement and memory.
– Norepinephrine
 Excitatory neurotransmitter of reticular system and involved
in eating, emotional behavior, learning & memory
– Dopamine
 Inhibitory neurotransmitter involved in movement,
emotional behavior, attention, learning, memory and
reward.
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Neurons and the
Neurotransmitters
 Neurotransmitters called monoamines
– Serotonin
 Inhibitory neurotransmitter involved in emotional behavior
(depression), arousal and sleep
– Gamma-amino Butyric Acid (GABA)
 Inhibitory neurotransmitter regulating arousal and inhibiting
general arousal of major neural systems
– Endorphins
 Inhibitory neurotransmitter involved as a natural analgesic
for pain reduction and also involved in emotional behavior,
eating & learning.
– Glutamate
 Major excitatory neurotransmitter in brain involved in
learning.
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Central Nervous System
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Central Nervous System
 Two parts of a nervous system
– Central Nervous System (CNS)
 The brain and the spinal cord
– Peripheral Nervous System (PNS)
 Connects the central nervous system to all other parts of
the body
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Central Nervous System
 Spinal cord
– An extension of the brain,reaching form the base of
the brain through the neck and spinal column, that
transmits messages between the brain and the
peripheral nervous system
– Protected by bone and spinal fluid
– Spinal nerves are 31 matched pairs with one on the
right side of the spinal cord and it’s counter part on
the left side of the spinal cord
– Basic reflexes (such as the quick withdrawal of the
hand from a hot surface) is controlled by the spinal
cord.
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Spinal Cord Reflex
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Central Nervous System
 Brainstem
– The structure that begins at the point where the
spinal cord enlarges as it enters the brain
– Medulla
 The part of the brainstem that controls heartbeat, blood
pressure, breathing, coughing, sneezing and swallowing
– Cerebellum
 Coordinates and regulates motor movements and muscle
control necessary for posture
– Pons
 Brainstem structure just above the medulla does finetuning of motor messages, programming species-typical
behaviors, processing sensory information and controlling
respiration
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Central Nervous System
 Brainstem (continued)
– Reticular Formation or Reticular Activating
System (RAS)
 Neural circuits extending from lower brain to thalamus that
play a critical role in arousal and alertness.
 Research suggest that Attention-Deficit Hyperactivity
Disorder (ADHD) results from insufficient arousal of the
noradrenergic system.
– Stimulant medications as amphetamines and Ritalin facilitate
norepinephrine and increase alertness helping ADHD
individuals to stay more alert and thus pay attention.
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Central Nervous System
 Limbic System
– Amygdala
 Expression of anger, rage, fear and aggressive behavior (intense
uncomfortable emotions)
– Hippocampus
 Plays an important role in memory
– Septum
 Plays an important role in the experiencing of pleasure (intense
comfortable emotions)
– Hypothalamus
 Helps maintain the bodies homeostasis (sleep, hunger, thirst,
body temperature, & sex drive), controls the pituitary gland which
in turn controls the endocrine (hormone) system, and emotional
expression
– Thalamus
 Relay station for routing sensory information to the cerebral
cortex and regulating sleep cycles (circadian rhythm)
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Central Nervous System
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Central Nervous System
 Basal Ganglia
– Initiation of motor movement and emotion
– Includes:
 Caudate Nucleus
– Control and initiation of motor movement
– Huntington’s Disease
 Putamen
– Control and initiation of motor movement
– Huntington’s Disease
 Substantia Nigra
– The midbrain structure that controls unconscious motor movements
– Parkinson’s Disease
– Ecstasy Users Beware
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Cerebrum
 Cerebrum
– Largest structure of the human brain comprised of billions of
neurons
– Consisting of the two cerebral hemispheres
– Connected by the Corpus Callosum
– Covered by the Cerebral Cortex
– Gray in color because neurons are not covered with myelin on
the surface.
– Inner core is white because neurons are not myelinated and
occur in three types:
 Commissural fibers - pass from one hemisphere to another
 Projection fibers – convey impulses to and from cortex
 Association fibers – connects various parts within a
hemisphere
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Cerebrum
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Cerebrum
Frontal Lobe
Temporal
Lobe
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Parietal Lobe
Occipital
Lobe
Cerebrum
Motor Cortex
Audition
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Somatosensory
Cortex
Visual
Somatosensory Man
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Cerebrum
 Sensory Cortex
– Involved in receiving sensory messages
– Primarily Parietal Lobes
 Motor Cortex
– Involved in transmitting messages to muscles for intentional
movement of body
– Primarily Frontal Lobes
 Association Cortex
– Largest portion of brain (75%)
– Integrating sensory and motor messages
– Higher functions such as thinking, interpreting & remembering
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Cerebrum
 Corpus callosum
– The thick band of nerve fibers that connects the two
cerebral hemispheres and make possible the
transfer of information and the synchronization of
activity between them
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Cerebrum
 Frontal lobes
– The lobes that control voluntary body movements,
speech production, and such functions as thinking,
motivation, planning for the future, impulse control,
and emotional responses
 Motor cortex
 Broca’s area
 Frontal association areas
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Cerebrum
 Motor Cortex
– The strip of tissue at the rear of the frontal lobes that
controls voluntary body movement
– Discovered by Fritsch and Hitzig
– Wilder Penfield
 Applied electrical stimulation to the motor cortex of
conscious human patients undergoing neurosurgery
 Mapped the primary motor cortex in humans
– Plasticity is maintained throughout life
 The capacity of the brain to adapt to changes such as brain
damage
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Cerebrum
 Broca’s area
– The area in the frontal lobe, usually in the left
hemisphere, that controls the production of speech
sounds
– Paul Broca
 Among the first scientists to demonstrate the existence of
localized functions in the cerebral cortex and concluded
that the site of damage was the part of the brain
responsible for speech production
– Broca’s aphasia
 An impairment in the physical ability to produce speech
sounds, or in extreme cases an inability to speak at all
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Cerebrum
 Bronca’s area (continued)
– Aphasia
 A loss or impairment of the ability to understand or
communicate through the written or spoken word, which
results from damage to the brain
 Frontal Association Areas
– Consists of association areas involved in thinking,
motivation, planning for the future, impulse control,
and emotional responses
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Cerebrum
Parietal lobes
The lobes that contain the somatosensory cortex
and other areas that are responsible for body
awareness and spatial orientation
Somatosensory cortex
– The strip of tissue at the front of the parietal lobe where
touch, pressure, temperature, and pain register in the
cerebral cortex
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Cerebrum
 Occipital lobes
– The lobes that contain the primary visual cortex and
association areas involved in the interpretation of
visual information
– Primary visual cortex
 The area at the rear of the occipital lobes where vision
registers in the cerebral cortex
 Each eye is connected the the primary visual cortex in both
right and left occipital lobes
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Cerebrum
 Temporal lobes
– The lobes that contain the primary auditory cortex,
Wernicke’s area, and association areas for
interpreting auditory information
– Primary auditory cortex
 The part of the temporal lobes where hearing registers in
the cerebral cortex
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Cerebrum
 Wernicke’s area
– The language area in the temporal lobe involved in
comprehension of the spoken work and in
formulation of coherent speech and written
language
– Wernicke’s aphasia
 Aphasia that results from damage to Wernicke’s area and
in which the person’s spoken language is fluent, but the
content is either vague or incomprehensible to the listener
– Another kind of aphasia is auditory aphasia
 Word deafness
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Cerebrum
 Temporal association areas
– House memories and are involved in the
interpretation of auditory stimuli
– There is a special association area where familiar
melodies are stored
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Cerebral Hemispheres
 Lateralization
– The specialization of one of the cerebral hemispheres to
handle a particular function
 Left hemisphere
– The hemisphere that controls the right side of the body,
coordinates complex movements, and in 95% of right-handers
and 62% of left-handers, controls most functions of speech
and written language
 Right hemisphere
– The hemisphere that controls the left side of the body and that,
in most people, is specialized for visual-spatial perception and
for interpreting nonverbal behavior
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Cerebral Hemispheres
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Cerebral Hemispheres
 Right hemisphere’s role in emotion
– The right hemisphere is involved in our expression
of emotion through tone of voice and facial
expressions
– Controls the left side of the face and usually
conveys stronger emotion than the right side of the
face
– Lawrence Miller
 Describes the facial expressions and the voice inflection of
people with right hemisphere damage as “often strangely
blank – almost robotic”
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Cerebral Hemispheres
Right hemisphere’s roles
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Cerebral Hemispheres
Left hemisphere’s roles
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Cerebral Hemispheres
 Split brain
– Split-brain operation
 An operation in which the corpus callosum is cut,
separating the cerebral hemispheres and usually lessening
the severity and frequency of grand mal seizures
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Cerebral Hemispheres
 Split brain (continued)
– Joseph Bogen and Philip Vogel
 Found that patients with severe epilepsy could be helped
by surgery that severed their corpus callosum rendering
communication between the two hemispheres impossible
– Roger Sperry and Michael Gazzaniga and Jerre
Levy
 Their research with split-brain patients has expanded
knowledge of the unique capabilities of the individual
hemispheres
– Roger Sperry
 Found that when the brain was surgically separated, each
hemisphere continued to have individual and private
experiences, sensations, thoughts, and perceptions
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Cerebral Hemispheres
 Roger Sperry 1981 Nobel Prize research
– The right hemisphere knows and remembers what it
sees just as well as the left, but unlike the left
hemisphere, the right cannot name what it has seen
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How the Brain is Studied
 Hans Berger
– Invented the electroencephalograph, a machine that
amplifies a million times the electrical activity
occurring in the brain
 Electroencephalogram
– A record of brain-wave activity made by the
electroencephalograph
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How the Brain is Studied
 Beta wave
– The brain wave associated with mental or physical
activity
 Alpha wave
– The brain wave associated with deep relaxation
 Delta wave
– The brain wave associated with slow-wave (deep)
sleep
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How the Brain is Studied
 Microelectrode
– An electrical wire
– So small that it can be inserted near or into a single
neuron without damaging it
– Can be used to monitor the electrical activity of a
single neuron or to stimulate activity within it
– Used to discover the exact functions of single cells
within the primary visual cortex and the primary
auditory cortex
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How the Brain is Studied
 CAT scan (computerized axial tomography)
– A brain-scanning technique involving a rotating Xray scanner and a high-speed computer analysis
that produces slice-by-slice, cross-sectional images
of the structure of the brain
 MRI (magnetic resonance imagery)
– A diagnostic scanning technique that produces highresolution images of the structures of the brain
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How the Brain is Studied
 PET scan (positron-emission tomography)
– A diagnostic scanning technique that produces highresolution images of the structures of the brain
 Functional MRI (fMRI)
– A brain-imaging technique that reveals both brain
structure and brain activity
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How the Brain is Studied
 SQUID (superconducting quantum
interference device)
– Images brain activity by measuring magnetic
changes produced by the electric current neurons
discharge when they fire
 MEG (magnetoencephalography)
– Measures magnetic changes produced by the
electrical activity from firing neurons and can also
image neural activity within the brain as rapidly as it
occurs, much faster than PET or fMRI
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Brain Across the Lifespan
 Synaptogenesis
– Process where synapses develop as a result of
growth of both dendrites and axons
– Pruning
 The process through which the developing brain eliminates
unnecessary or redundant synapses
 Myelination
– The development of myelin sheaths around axons,
begins prior to birth but continues well into
adulthood
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Brain Across the Lifespan
 Hemispheric specialization
– Language processing occurs primarily in the left
hemisphere
– Spatial perception is not lateralized to right side but
not until around the age of 8
 Plasticity
– The ability of the brain to reorganized, to reshape
itself in response to input from both internal and
external sources, and to compensate for damage
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Brain Across the Lifespan
 Stroke
– The most common cause of damage to adult brains,
arising when blockage of an artery cuts off the blood
supply to a particular area of the brain or when a
blood vessel bursts
– A high percentage of stroke survivors suffer from
depression
– Patients who receive TPA (a blood clot-dissolving
drug) within 3 hours of the onset of a stroke are
30% more likely to have minimal or no disability
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Peripheral Nervous System
 Peripheral Nervous System (PNS)
– The nerves connecting the central nervous system
to the rest of the body
– Contains two subdivisions
 Somatic Division
 Autonomic Division – contains two divisions
– Sympathetic Division (Activates)
– Parasympathetic Division (Inhibits)
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Peripheral Nervous System
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Peripheral Nervous System
 Somatic Division
– Consists of all the sensory nerves, which transmit
information from the sense receptors-eyes, ears,
nose, tongue, and skin-to the central nervous
system
– Consists of all the motor nerves, which relay
messages from the central nervous system to all the
skeletal muscles of the body
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Peripheral Nervous System
 Autonomic Division
– Operates without any conscious control or
awareness on your part
– Transmits messages between the central nervous
system and the glands, the cardiac muscle, and the
smooth muscles
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Peripheral Nervous System
 Autonomic Division (continued)
– Divided into two parts
 Sympathetic nervous system
– Mobilizes the body’s resources during stress,
emergencies, or heavy exertion, preparing the body for
action
– Named the fight-or-flight response by Walter Cannon
 Parasympathetic nervous system
– Associated with relaxation and the conservation of energy.
The division that brings the heightened bodily responses
back to normal following an emergency.
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Peripheral Nervous System
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Endocrine System
 Endocrine system
– A system of ductless glands in various parts of the
body that manufacture and secrete hormones into
the bloodstream or lymph fluids, thus affecting cells
in other parts of the body
– Hormones
 A substance manufactured and released in one part of the
body that affects other parts of the body
 Chemical messengers of the endocrine system
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Endocrine System
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Endocrine System
 Pituitary gland
– The endocrine gland located in the brain and often
called the “master gland”, which releases hormones
that control other endocrine glands and also
releases a growth hormone
– Releases the hormones that activate the other
glands in the endocrine system
– Brain controls activity of the pituitary gland through
the production of a group of chemicals known as the
hypothalamic-releasing factors
– Hormones exert primary influence over a single
organ or specific cells which are referred to as
target organs.
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Endocrine System
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Endocrine System
 Thyroid gland
– Produces the important hormone thyroxine, which
regulates the rate at which food is metabolized
 Pancreas
– Regulates the body’s blood sugar levels by
releasing the hormones insulin and glucagon into
the bloodstream
 Adrenal glands
– A pair of endocrine glands that release hormones
that prepare the body for emergencies and stressful
situations and also release small amounts of the sex
hormones
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Endocrine System
 Gonads
– Sex glands –the ovaries in females and the testes in
males
– Release the sex hormones that make reproduction
possible and that are responsible for the secondary
sex characteristics
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Depressants & Behavior
 Sedatives
– Class includes tranquilizers, barbituates & non-barbituates
– Induce relaxation, calmness and sleep
 Opiates (Narcotics)
– Includes opium, morphine, codeine & heroine
– Widely used as pain killers
 Alcohol
– Dampens impulse control (less inhibited)
– Withdrawal (nausea, vomiting, fever, shakes [delirium tremens]
& bizzare hallucinations
– 0.10% blood alcohol level is 5 times more likely to have a car
accident
– Loss of memory, Fetal Alcohol Syndrome
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Stimulants & Behavior
 Caffeine
– Most widely used stimulant
– Chocolate, tea, coffee
– Heart and respiration rates and blood pressure increase
– Blocks adenosine receptors
 Adenosine is an inhibitory neurotransmitter that produces neural
sedation and regulates the dilation of blood vessels (Julian, 2001)
 Nicotine
– Second most widely used stimulant
– Tobacco products
– Increases heart rate, blood pressure and stomach activity while
constricting blood vessels
– Withdrawal causes craving for tobacco, increased appetite, stomach
cramps, headaches, restlessness, irritability, insomnia, anxiety and
depression
– Smoking causes higher incidents of miscarriages, still births, low
birth-weight babies and babies who die from Sudden Infant Death
Syndrome (SIDS) [Zotti, 2003]
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Stimulants & Behavior
 Amphetamines
– Benzedrine, Dexedrine, Methedrine, Methamphetamine (street drug),
– Dramatically increase alertness and activity and counteract fatigue
and promote feelings of euphoria and well-being
– Likely works on norepinephrine and dopamine by increasing the
amount released from the nerve terminal and blocking reuptake
 Cocaine
– Made from the leaves of coca shrub and was active ingredient in
Coca Cola until 1903
– Increases heart rate & respiration rates, constricts blood vessels and
dilates the pupils
– High only last 20-30 minutes so reuse must occur quickly
– Perhaps most addictive drug we know
– Heart and lung damage are common as well as anemia, damage to
the nasal tissue, immune system impairment and rare cases of
sudden death.
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Hallucinogens & Behavior
 LSD (Lysergic acid diethylamide)
– Derived from a fungus that grows on rye grass
– Profound distortions of sensations, feelings, time & thought
– Suppresses the activity of Serotonin thus dream activity becomes activated
without restraint
 Psilocybin (Mushrooms)
– Suppresses the activity of Serotonin
 Mescaline (Peyote Cactus)
– Effects the way the brain responds to Norepinephrine & Acetylcholine
 Ecstasy (MDMA)
–
–
–
–
Body and visual distortions
Depersonalization
Releases large amounts of Serotonin and interferes with synthesis of Serotonin
Hyperthermia, rapid heart rate, high blood pressure, muscle rigidity and
convulsions
– Appears to irreversibly destroy serotonin-containing neurons
– Parkinson’s Disorder Syndrome
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Hallucinogens & Behavior
 Marijuana
– Derived from hemp plant Cannibis Sativa
– THC (delta9-tetrahydrocannabinol)
– Hallucinogen at high levels but usually a stimulant and depressant
effect
– Increased heart rate & enhanced appetite
– Small doses create euphoria and enhance some sensory experiences
– Impairs reaction time and ability to concentrate
– Some people become confused, agitated or extremely anxious
– Has proved effective in epilepsy and glaucoma and reduces nausea
during chemotherapy treatment of cancer patients
 Anadamide
– Devine et al., 1992
 Brains natural THC
 Regulates mood, pain, movement and appetite
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