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Nervous System
Nervous system
It is the master controlling and communicating system
of the
body. Its signaling device, or means of communicating
with body cells, is
electrical impulses, which are rapid and specific and
cause almost
immediate responses.
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General Psychology
Three Overlapping Functions
1) Much like a sentry, it uses its millions of sensory receptors to
monitor changes occurring both inside and outside the body. These
changes are called stimuli and the gathered information is called
sensory input.
2) It processes and interprets the sensory input and makes
decisions about what should be done at each moment- a process
called integration.
3) It then effects a response by activating muscles or glands; the
response is called sensory output.
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General Psychology
Structural Classification
The central nervous system (CNS) consists of the
brain and spinal cord, which occupy the dorsal body
cavity and act as an integrating and command centers
of the nervous system. They interpret the incoming
sensory information and issue instructions based on
past experience and current conditions.
The peripheral nervous system (PNS), the part of the
nervous system outside the CNS, consists mainly of
the nerves and extend from the brain and spinal cord.
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General Psychology
Brain
Spinal
cord
Central
Nervous
System
Peripheral Nervous
System
somatic nervous system (voluntary
movements)
 autonomic nervous system (involuntary
movements)



sympathetic nervous system (arouses/excites the body)
parasympathetic nervous system (relaxes or calms the
body)
Cell Structure
Neuron: cell composed of a cell body, an axon
and dendrites, forming a functional unit of the
nervous system.
Cell body: part of the nerve cell between the
axon and the dendrite.
Nucleus: central part of a cell, containing the
chromosomes.
Dendrite: receives information from other
neurons
Axon: brings information away from the cell
body and send information towards other
neurons
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General Psychology
Neurotransmitters
These are chemicals located and released in the brain to
allow an impulse from one nerve cell to pass to another
nerve cell.
There are approximately 50 neurotransmitters identified.
There are billions of nerve cells located in the brain,
which do not directly touch each other. Nerve cells
communicate messages by secreting neurotransmitters.
Neurotransmitters can excite or inhibit neurons (nerve
cells) or both.
Drugs that interfere with neurotransmitters are called agonist
(drugs that increase or mimics the neurotransmitters) and
antagonist (those that blocks the effects of the transmitters)
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General Psychology
Some Common Neurotransmitters
1.Acetylcholine (Ach)
2.Gamma-aminobutyric acid (usually
abbreviated to GABA)
3.Norepinephrine
4.Dopamine
5.Serotonin
6.Endorphine
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General Psychology
acetycholine (Ach)




simulates firing of neuron
involved in the action of muscles, learning and
memory
found in the CNS and PNS
eg: venom/poison of a black widow =
stimulates to make spasms
poison dart/tranquilizers = blocks the receptors for Ach,
paralyzing the person
nicotine = stimulates the receptors
Alzheimer’s disease (Ach deficient)
acetycholine (Ach)
Gamma-aminobutyric acid
(GABA)





found in the CNS (1/3 of the brains
synapse)
keeps many neurons from firing
controls the preciseness of the signals
carried from 1 neuron to the other
low level of GABA = anxiety
valium increases inhibiting effect of GABA
Norepenipherine
Both a hormone and a nuerotransmitter
 usually inhibits firing of neurons BUT excites the
heart muscles, intestines etc.
eg: stress stimulates the release norepenipherine
 controls allertnes
 Too little of norepenipherine = depression ; too
much = manic states

Dopamine





mainly inhibits
helps control voluntary movement
affects sleep, mood, attention and learning
eg. Stimulants like cocaine/amphetamines produce
excitement, alertness, decreased fatigue and
increased motor activity
facilitates critical brain functions and, when
unusual quantities are present, abnormal
dopamine neurotransmission may play a role in
Parkinson's disease, certain addictions, and
schizophrenia.
Dopamine
Serotonin






also inhibits
regulates sleep, mood, attention and learning
regulates sleep and wakefulness w/ acetycholine
and norepinepherine
low level of serotonin is associated with
depression
PROZAC (antidepressant) increase the brain
levels of serotonin
concentrated in certain areas of the brain; the
hypothalamus and midbrain contain large
amounts, while the cortex and cerebellum contain
low concentrations.
Serotonin
Endorphins
is one of the body's own painkillers, an opioid
(morphine-like) chemical produced by the body
that serves to suppress pain.
 Manufactured in the brain, spinal cord, and many
other parts of the body.
 Endorphins act as analgesics (diminishing the
perception of pain) and as sedatives.
 natural opiate
 stimulates other neurons
 protects the body from pain and elevates pleasure
eg. morphines - anesthesia

Levels of
Organization
of the
Brain
Hindbrain
a. Medulla




When the spinal cord
enters the skull
Controls breathing
Regulates reflexes
Allows us to maintain
an upright
b. Cerebellum
rear of hindbrain, just
above the medulla
 rounded structure that
are important in motor
coordination
ex. Arm and leg
movement.: playing the
piano, playing

c. Pons
bridge in the hindbrain
contains several fibers
involved in sleep and
arousal

Midbrain




located in between the
hindbrain and forebrain
contains several nerve
fibers that ascend and
descend to connect
higher and lower
portions of the brain.
Relays information
between the brain and
eyes & ears.
Linked to our ability to
attend to an object
visually
a. reticular formation

collection of
neurons involved
in stereotyped
patterns of
behavior eg.
Walking, sleep,
turning to attend
to a sudden
noise.
Brain stem
-includes most of the
hindbrain and midbrain
(except the cerebellum)

- Connects the spinal
cord until the reticular
formation

- Most ancient part of
the brain (500 Million
yrs”)

- Clumps of cells that
determine alertness
and regulates basic
survival functions ex.
Breathing, heart beat,
blood pressure.
Forebrain
 highest
level of
the human brain
A. LIMBIC SYSTEM


loosely connected of structures under the
cerebral cortex
important in memory and emotion
1. AMYGDALA (Latin for “almond” shape)
- located at the base of the
temporal lobe
- involved in the
discrimination of objects
necessary for survival
Ex food, mates ,social rivals
- neurons in the amygdala
fires selectively to such
stimuli
- involved in emotional
awareness and expression
DAMAGE: eat, fight or mates
with inappropriate objects
2. HIPPOCAMPUS
role in storage of memories
DAMAGE: Individuals do
not retain new conscious
memories after the
damage
NOTE: Memories are not
stored in the limbic
system but determine
what information should
have a lasting neural
traces in the cortex.
B. Thalamus
located on top of the brain
stem in the central core of
the brain.
 sorts information and send
it to the appropriate places
in the forebrain for further
information and integration
 involved in sense receptors
 involved in sleep and
wakefulness
(with reticular formation)
Ex. cerebellumthalamusmotor
area(cerebral cortex)

C. Basal Ganglia
located above the
thalamus, under the
cerebral cortex
 clusters of neurons
 works with the cerebellum
and cerebral cortex to
control and coordinate
voluntary movement
 enables for habitual
behavior
Ex. riding a bicycle, driving
DAMAGE: can cause
unwanted movements
Ex. jerking of limbs
Or too little movement
Ex. like Parkinson’s disease

D. Hypothalamus
small forebrain structure
below the thalamus
 monitors three
pleasurable activity
1. Eating 2. drinking 3.
sex
 involved in emotion,
stress, rewards
 sensitive to change in
blood & neural output

E. Cerebral cortex
highest region in the forebrain
 most recently developed
 involved in highest mental function:
thinking/planning
 convoluted

E. Cerebral cortex
F. LOBES
1. Occipital lobe
back of the head
 responds to visual
stimulus
 connect to process info.
On visual stimuli
ex. Color, shape,
motion
damage: blindness

2. Temporal lobe
part of cerebral cortex
above the ears
 involved in hearing,
language, processing &
memory
 connected to the limbic
system
damage: can not retain
experiences to long
term memory

3. Frontal lobe



found in the cerebral
cortex behind the for
brain
involved in control of
voluntary muscles,
intelligence and
personality
eg. Phineas Gage (Sept
13, 1848) prefrontal
cortex (responsible for
planning and
monitoring/organizing
thinking) was damaged.
4. Parietal lobe



located on top of the
rear head
involved in registration
of spatial location,
attention and motor
cortex
eg. Judging how far the
buildings are
G. Cortexes





visual cortex: vision
and sight
auditory cortex:
hearing and sound
prefrontal cortex:
planning, reasoning
motor cortex:
voluntary movement
somatosensory: body
sensation
Association cortex/Association areas
comprises 75% of the cerebral cortex
 integrates information among the other cortex
+ a damage to a specific part does not result in
specific loss of a function (except for the language
areas
eg:
 Broca’s area which is involved in speech production
 Wernicke’s area which is involved in
comprehending language.

Cerebral Hemispheres
Cerebral Hemispheres


Roger Sperry (1974)
had an epileptic patient
called W.J.
created the split brain
theory
Left
Right
Connected by the corpus callosum
Receives information
from the right side of the
body
Speech & grammar
Receives information
from the left side of the
body
Appropriate use of
language
Logic, mathematics
Processes non-verbal
info.
Processes verbal
Spatial reasoning, visual
recognition, and
emotional recognition
information