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Intro to Psychology
The Brain
1
Chapter 3
The Brain
I.
Brain Circuits
A. Structural Components
1. Neurons
a. 3 functions of neurons
1. sensory neurons –
receive information from
environment
2. motor neurons – send
information from brain to
parts of body
3. interneurons –
intermediaries between
motor and sensory
neurons; receive and
send information
b. parts of the neuron
(diagram p. 48)
c. glial cells – hold neurons in
place; care and feeding of
neurons
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The Brain
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B. The Nerve Impulse
1. electrochemical
2. resting potential – neuron at rest;
-70 millivolts
3. threshold – the point when
neuron can fire
4. action potential – charge moves
down axon; terminal buttons
release chemical signal
5. refractory phase
absolute
relative
6. all-or-none law - either action
potential occurs or it doesn’t
7. Ion Flow
a. threshold is reached
b. ion channels open
c. positively charged sodium
enters the neuron (-K)
d. neuron depolarizes, going
from a neg. to pos. valence
e. when action potential
completed, the Na+ is
pumped out and K- returns
f. repolarization to neg.
8. myelin – fatty substance that
speeds transmission of impulse
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The Brain
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C. Neurotransmitters
1. The synapse – place where an
axon of one neuron meets the
dendrite or cell body of another
neuron
2. synaptic cleft – the gap between
the axon on one neuron and the
membrane of another, across
which communication occurs
See Fig. 2.5 p. 50
3. Types
a. excitatory
b. inhibitory
4. best known
a. acetylcholine (Ach) – memory
b. dopamine (DA) – movement,
attention, learning
c. serotonin (5-HT) – sleep,
arousal, mood, appetite,
sensitivity to pain
d. histamines – vasoconstriction and dilation
5. neuromodulators
opiod peptides
endorphins
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The Brain
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6. receptor – site where a
messenger molecule attaches
itself; lock and key
7. reuptake – process by which
surplus neurotransmitter is
reabsorbed back into the
sending neuron so that the
neuron can fire again
8. agonist – chemical that mimics
the effects of a neurotransmitter;
may prevent reuptake
9. antagonist – chemical that blocks
the effect of a neurotransmitter;
block a receptor or enhance
reuptake
II. The Nervous System
Diagram Fig. 2.8 p. 55
A. Spinal Cord – flexible rope of nerves
that runs inside the backbone
B. Central Nervous System (CNS)
1. brain
2. spinal cord
3. reflex – an automatic response to
an event
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The Brain
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C. Peripheral Nervous System (PNS)
links the CNS to the organs of the
body
2 parts:
1. autonomic nervous system
(ANS) - controls the smooth
muscles, some glands, and selfregulating systems (i.e.
digestion, circulation)
2 parts:
a. sympathetic nervous system
1.
fight or flight;
increases in
a.
heartrate
b.
respiration
c.
sweating
d.
salivation
e.
dilating pupils
f.
decreases
digestion
b. parasympathetic nervous
system – reverses effects of
sympathetic nervous system
2. somatic system – voluntary
movements
3.
Intro to Psychology
The Brain
III. The Brain
A. Hindbrain
1. medulla oblongata
a. heart rate
b. breathing
c. swallowing
d. digestion
2. pons
a. signals between parts
b. reticular activating system
3. cerebellum
a. coordination
b. balance
c. muscle tone
B. Midbrain
1. reticular activating system
a. regulates consciousness
b. heart rate
c. breathing
2. superior colliculi
a. vision
3. inferior colliculi
a. hearing
C. Forebrain
1. Limbic system
a. Includes:
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The Brain
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1. hippocampus – memory
formation
2. amygdala – anger and
aggression
3. septum – anger and fear
b. learning
c. motivation
d. emotions (inhibition)
4. thalamus
a. receives sensory information
and projects to other parts of
the brain
b. sleep and waking
5. hypothalamus
a. controls endocrine system
b. ANS
c. internal temperature
d. fight
e. flight
f. feeding
g. mating
D. Cerebral Cortex
1. gray matter
2. convolutions
3. hemispheric specialization
a. “split-brain” research
b. corpus callosum
Intro to Psychology
The Brain
c. left brain
1. language
2. speech
3. writing
4. calculation
5. time sense
6. rhythm
7. ordering of complex
movements
d. right brain
1. nonverbal
2. perceptual abilities
3. visualization
4. recognition of patterns,
faces, and melodies
5. recognition and
expression of emotion
6. spatial skills
7. simple language
comprehension
4. Lobes of the cerebral cortex
a. frontal
1. primary motor cortex
2. planning, control related
to movement
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The Brain
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b. parietal
1. somatosensory area
2. touch
3. temperature
4. pressure
5. other body sensations
c. temporal
1. auditory area
2. left temporal area –
language
d. occipital
1. visual area
E. Brain injury
1. Neglect – nonattention to
opposite visual field
2. Aphasia – impaired ability to use
language
a. Broca’s area damage
1. left frontal lobe
2. can read and understand
speech
3. difficulty speaking and
writing
4. expressive aphasia
b. Wernicke’s area damage
1. left temporal lobe
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The Brain
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2. can speak, but not
understand
3. receptive aphasia
4. agnosia – “mindblindness”; inability
to recognize objects
facial agnosia – inability to recognize
faces
IV. The Endocrine System
A. Hormones – chemical substances
secreted by the endocrine glands
B. Pituitary gland
1. “master” gland
2. regulates growth
growth hormone
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The Brain
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C. Thyroid gland
1. regulates metabolism
2. overactive
a. thin
b. tense
c. excitable
d. nervous
3. underactive
a. inactivity
b. sleepiness
c. slowness
d. overweight
C. Adrenal glands
1. located on top of kidneys
2. produce adrenaline and
noradrenaline
3. sexual development
V. Brain Scans
A. Angiogram
1. enhanced x-rays
2. assess vascular disease
B. Computerized axial tomogram (CAT)
1. 3 dimensional x-ray
2. cross-sections of brain
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The Brain
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C. Magnetic resonance imaging (MRI)
1. clearer and more detailed than
CAT
2. uses magnetic field to analyze
particle reactions in blood and
tissue
D. Positron emission tomography (PET)
1. radioactive glucose used
2. glucose absorption rates
analyzed
E. Electroencephalograph (EEG) –
records electrical current produced
by brain