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The nervous system
The nervous system is an organ system containing a network of specialized cells called
neurons that coordinate the actions of human and transmit signals between different parts of
its body.
The human nervous system has two main divisions as seen in the concept map, they are the
central nervous system and the peripheral nervous system.
Two main system:
- The central nervous system (CNS) contains the brain and spinal cord.
- The peripheral nervous system (PNS) includes the somatic motor nervous system, and the
autonomic nervous system.
The central nervous system (CNS):
1) The largest part.
2) Enclosed and protected by meninges, a three-layered system of membranes.
3) Acts as the central control region of the nervous system because it processes information
and issues commands.
The peripheral nervous system (PNS):
1) A collective term for the nervous system structures that do not lie within the central
nervous system (CNS).
2) Two nervous system:
- The somatic motor nervous system: consists of the nerves that send sensory
information to the central nervous system AND motor nerve fibers that project to skeletal
muscle.
- The autonomic nervous system: controls smooth muscle of the internal organs and
glands. It carries information from the CNS to organs, blood
 regulates heart rate, respiration, digestion and pupil contraction.
 control muscle contraction in walls of blood vessels, digestive, urinary and
reproduction tracts.
 carries messages to help stimulate glands to secrete tears, mucus and digestive
enzymes
- It is divided into two parts: the sympathetic nervous system and the enteric nervous
system.
Sympathetic Nervous System: arouses the body.
Parasympathetic Nervous System: clams after arousal.
A neuron or a nerve cell:
1) A neuron is a cell of the nervous system and has cell membranes and nucleus. Neurons
contain cytoplasm, mitochondria and other organelles and carry out basic cellular processes,
such as energy production, and information through an electrochemical process.
2) Three parts: cell body, and axon. Neurons have specialized extensions called dendrites
and axons. Dendrites bring information to the cell body and axons take information away
from the cell body.
3) Neurons can also be classified by the direction that they send information.
- Sensory (or afferent) neurons: send information from sensory receptors (e.g., in skin,
eyes, nose, tongue, ears) toward the central nervous system.
- Motor (or efferent) neurons: send information away from the central nervous system to
muscles or glands.
- Interneurons: send information between sensory neurons and motor neurons. Most
interneurons are located in the central nervous system.
Neurotransmitter
1) A chemical messenger that carries, boosts and modulates
signals between neurons and other cells in the body.
2) A neurotransmitter is released from one neuron at the axon
terminal. Then, neurotransmitters cross the synaptic gap to
reach the receptor site of the other cell or neuron.
3) Then, in a process known as reuptake, the neurotransmitter
attaches to the receptor site and is reabsorbed by the neuron.
4) The action of neurotransmitters can be stopped by four different mechanisms:
- Diffusion: Drifting away the neurotransmitter to out of the synaptic cleft where it can no
longer act on a receptor.
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- Enzymatic degradation (deactivation): A specific enzyme changes the structure of the
neurotransmitter so it is not recognized by the receptor.
- Glial cells: Astrocytes remove neurotransmitters from the
synaptic cleft.
- Reuptake: That the whole neurotransmitter molecule is
taken back into the axon terminal that released it. So, these
neurotransmitters are removed from the synaptic cleft so they cannot bind to receptors.

The spinal cord
1) The spinal cord is the extension of the central nervous
system and the main pathway for information connecting the
brain and peripheral nervous system.
2) The human spinal cord is protected by the bony spinal
column that is made up of bones called vertebrae.
3) The spinal cord works by receptors.
Receptors in the skin send information to the spinal cord through the spinal nerves. The
nerve fibers enter the spinal cord through the dorsal root. Some fibers make synapses with
other neurons in the dorsal horn, while others continue up to the brain. Many cell bodies in
the ventral horn send axons through the ventral root to muscles to control movement.
- Receptors in the skin -> the spinal nerves -> the dorsal root -> the dorsal horn -> the
ventral root -> muscles -> control movement
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Primary organization of the BRAIN
1. Hindbrain: largely unconscious, but
essential functions like breathing,
circulation, balance and wakefulness. (also
the oldest part of the brain)
Includes:
medulla: involved in regulation basic life
functions
Pons: involved with sleep and wakefulness
Cerebellum: is involved in controlling
balance and coordination
2. Midbrain: Preliminary integration of vision
and hearing.
3. Forebrain: more complex sensory
processing, regulation of biological needs
and emotions. Also complex thought.
Includes:
Thalamus: relay station for sensory information (sending the info about vision to one
area, info about hearing to another area)
Hypothalamus: regulates many vital bodily functions: body temperature, reproduction,
emotional states, responses to stress, aggression, hunger and thirst.
Limbic system: memory and emotional processing
Cerebral cortex: Brain’s thinking,
calculation, organizing, and creative center.
(Takes up most of the room inside the skull)
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CEREBRUM
Takes up most of the room inside the skull and the outer covering is called the cerebral
cortex, which covers the cerebrum like a cap and is no more than an inch thick but essential
for thinking, calculating, organizing and creativity. The cerebrum and cerebral cortex are the
most recently evolved portions of the brain and they regulate most complex behavior.
The cerebrum is divided into two large masses called the right and left hemisphere.
They in turn are connected by a thick bundle of nerve fibers called corpus callosum (latin
“thick body”). This connection between the right and left hemispheres is a pathway that each
hemisphere uses in order to share information, communication and coordinate their
activities.
The left and right hemispheres share some functions but they are also specialized in
certain tasks. The right side of the brain controls the left side of the body and vice versa.
Right Hemisphere: Visual and spatial tasks, music, visual imagery, face recognition and
perception of emotion.
Left Hemisphere: Language, math and logic
Each hemisphere is divided into four lobes, delineated by deep fissures on the surface of the
brain.
Occipital Lobes: Receives and processes Visual information.
Parietal Lobes: Receives sensor information from sense receptors all over the body.
Touching processing and monitoring body position.
Temporal Lobes: Involved in complex visual tasks; balance, regulates emotions, strong
role in understanding language. Contains centers of hearing, smells and memory.
Frontal lobes: coordinate body movements and control fine muscles such as tongue and
fingers. Coordinates messages from other cerebral lobes; involved in complex problem
solving tasks. Controls higher mental functions like thinking, planning, problem solving, and
decision making and accessing and acting on stored memories.
Prefrontal cortex: executive control functions
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Vocabulary Words
1. Sensory neurons: send information from sensory receptors (e.g., in skin, eyes, nose,
tongue, ears) toward the central nervous system.
2. Motor neurons: send information away from the central nervous system to muscles or
glands.
3. Diffusion: Drifting away the neurotransmitter to out of the synaptic cleft where it can no
longer act on a receptor.
4. Reuptake: That the whole neurotransmitter molecule is taken back into the axon terminal
that released it.
5. The spinal cord is the extension of the central nervous system and the main pathway for
information connecting the brain and peripheral nervous system.
6. Cerebrum: The largest and most complex portion of the brain. It controls thought,
learning and other complex activities.
7. Cerebral cortex: the outer layer of the cerebrum, composed of six cell layers of deeply
folded and ridged gray matter.
8. Corpus callosum: a large bundle of nerve fibers that connect the two cerebral
hemispheres.
9.Occiptial lobe: the region at the back of each cerebral hemisphere that contains the center
of vision and reading ability.
10. Parietal lobe: the middle lobe of each cerebral hemisphere between the frontal and
occipital lobes; it contains important sensory centers and therefore process information
relating to touch, pressure, temperature, pain and body movement.
11. Frontal lobe: the top, front regions of each of the cerebral hemispheres. They are used
for reasoning, emotions, judgment and voluntary moment.
12. Temporal lobe: the region at the lower side of each cerebral hemisphere; contains center
of hearing and memory.
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Quiz Questions
1. How many parts does a neuron have? What are these?
2. What is a neurotransmitter? What does it do?
3. Match each item in the left column to the corresponding item on the right column
I. Parietal lobes
a. controls thinking, planning and problem solving
II. Temporal lobes
b. process language and information to the ears
III. Occipital lobes
c. process body sensations
Iv. Frontal lobes
d. process visual information
4. The cerebral cortex is the largest and most complex portion of the brain. T/F
5. The Corpus Callosum is a large bundle of nerve fibers that connects _________________
and_____________________, which is used to communicate and share information with
each other.
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Presentation Outline
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Upon completing the map, it was becoming clear to researchers that
each side of the brain had a characteristic way that it both interpreted the
world and reacted to it. The chart below will help illustrate the
characteristics which are known to reside on each side of our brains.
The right hemisphere control the left side of the body and the left
hemisphere controls the right side.
LEFT BRAIN FUNCTIONS
uses
logic
detail oriented
facts
rule
words and language
present
and past
math and science
can
comprehend
knowing
acknowledges
order/pattern perception
knows
object name
reality based
forms
strategies
practical
safe
RIGHT BRAIN FUNCTIONS
uses
feeling
"big picture"
oriented
imagination rules
symbols
and images
present and
future
philosophy & religion
can
"get it" (i.e.
meaning)
believes
appreciates
spat
ial perception
knows object
function
fantasy based
presents
possibilities
impetuous
risk taking
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