SCIENCE 10
QUARTER 3
MODULE 2 – WEEK 3
THE
NERVOUS
SYSTEM
MELCs:
Describe how the nervous
system coordinates and
regulates these feedback
mechanisms to maintain
homeostasis (S10LT-IIIc-36)
OBJECTIVE:
At the end of the lesson the learners will be able to:
 Identify the parts and functions of
the nervous system
REVIEW
LOOKING BACK!
Name the system in the following Figures:
I know them so well…
RESPIRATORY SYSTEM
B. MUSCULAR SYSTEM
C. SKELETAL SYSTEM
D. CARDIOVASCULAR
OR CIRCULATORY SYSTEM
D. DIGESTIVE SYSTEM
LESSON:
THE
NERVOUS
SYSTEM
( body control
and response)
The NERVOUS SYSTEM is the
major control of Homeostasis.
 It provides monitoring,
response, and regulation of
all systems.
 The nervous system connects all
your body parts and transmits
signals from one part to
another.
 It is a system of cells, tissues and
organs that gather information
about the environment and helps
us respond appropriately to a
situation.
 It regulates the body’s
responses to internal and
external stimuli.
 The basic purpose of the Nervous
System is to coordinate all of the
activities of the body. It enables
the body to respond and adapt to
changes that occur both inside
and outside the body.
 The nervous system has two main
parts: the CENTRAL NERVOUS SYSTEM
(CNS) and the PERIPHERAL NERVOUS
SYSTEM (PNS)
 The CENTRAL NERVOUS SYSTEM (CNS)
is consists of the brain and spinal cord
 It is where the interneurons receive
and pass on messages.
a. BRAIN -Organ
located within
the skull, or
cranium that
functions as
organizer and
distributor of
information
for the body.
 The BRAIN is a moist and spongy
organ with an average of 3 pounds in
weight and it is about 2% of the total
body weight.
 It consists of 10 billion neurons that
control everything a person does, such
as thoughts, movements, memory and
sense
3 Main parts
of the BRAIN
3 Main parts
of the BRAIN
1. CEREBRUM
 Large
 Located on the
upper part
1. CEREBRUM
 Controls activity and
thought
(your ability to speak, think
and move).
 Compared to animals, humans have pretty
big cerebrums, which is why you can talk
and do math problems and your dog can't.
1. CEREBRUM
 cerebrum is
split into two
halves, giving
it a right side
and a left side
(hemispheres)
1. CEREBRUM
Right brain – left brain
The cerebrum is divided
into two halves which
are joined by a bundle
of fibers called corpus
callosum that transmits
message from one side
to the other.
1. CEREBRUM
Right brain – left brain
 Each hemisphere
controls the opposite
side of the body.
 If a stroke occurs on
the right side of the
brain, your left arm or
leg maybe weak or
paralyzed.
1. CEREBRUM
 If you are good at music or drawing, then
we'd say you're right-brained because it is
thought that the right half of the cerebrum
controls creativity and artistic abilities.
 If you are good at math or solving problems,
then you would be seen as left-brained
because the left side controls more of these
logical types of thought.
1. CEREBRUM –
 Each half of the Cerebrum is further
divided into four different lobes:
1. CEREBRUM -
Four Different Lobes of CEREBRUM
Frontal lobe is the higher, control center
where consciousness lies and is involved
in problem solving. It is responsible for
reasoning and thought
Four Different Lobes of CEREBRUM
Parietal lobe perceives stimuli such as
taste and somatosensory (touch) as well
as aiding speech and reading. It integrates
sensory information
Four Different Lobes of CEREBRUM
Occipital lobe is devoted to processing
visual information from the eyes
Temporal lobe controls hearing and
speech, as well as being involved in the
integration of 2 or more senses into a
meaningful concept.
3 Main parts
of the BRAIN
2. CEREBELLUM
or “Little Brain”
 Hanging down from the cerebrum
like a bell is the much smaller
cerebellum
2. CEREBELLUM
 controls posture, coordination and
balance
2. CEREBELLUM
 If you are coordinated, it means you
can make your muscles work
together.
2. CEREBELLUM
 So using your body to throw a baseball
or sink a free throw requires good
coordination. When you learned to
ride a bike it took both coordination
and balance, so you can thank your
cerebellum for that skill.
3 Main parts
of the BRAIN
3. BRAIN STEM
 It connects the
brain to the spinal
cord
3. BRAIN STEM
 controls vital, life
support, involuntary
activities (automatic
functions such as
breathing, heart rate
and blood pressure.
B. The other half of the
CNS is the SPINAL CORD,
which is a rod of brain
tissue that extends
about two-thirds of the
way down the back, just
below the ribs.
 It is the link between the brain and
the nerves in the rest of your body.
 This serves as a channel for signal
between the brain and the rest of
the body, and controls simple
musculoskeletal reflexes without
input from the brain.
 The spinal cord is divided into different
regions: the cervical, thoracic, lumbar, sacral,
coccygeal
 The PERIPHERAL NERVOUS SYSTEM
(PNS) contains all nerves that extend
outside the brain and spinal cord.
 This consists of sensory and motor
nerves, whereby the sensory nerves
carry information to the CNS, while
the motor nerves carry information
away from the CNS.
 It has two main divisions, which are
the Somatic Nervous System, and the
Autonomic Nervous System.
A. SOMATIC NERVOUS SYSTEM (SNS)
 communicates with sense organs and
voluntary muscles.
 This system is associated with the
voluntary control of body movements
and has two main parts
TWO MAIN PARTS OF SNS
1. SPINAL NERVES
 the nerves that carry motor and
sensory signals between the spinal
cord and the body.
TWO MAIN PARTS OF SNS
1. SPINAL NERVES
 Afferent (sensory input)
Carries information from the body
to the brain
TWO MAIN PARTS OF SNS
1. SPINAL NERVES
 Efferent (motor input)
Carries information from the brain
to the body
TWO MAIN PARTS OF SNS
2. CRANIAL NERVES
 the nerve fibers that carry
information into and out of
the brain stem.
B. AUTONOMIC NERVOUS SYSTEM
(SNS)
 This system is associated with the
involuntary control of body
movements and supplies smooth
muscle and glands, and thus influences
the function of internal organs.
 Within the brain, the autonomic
nervous system is regulated by the
hypothalamus.
 Autonomic functions include control of
respiration, cardiac regulation, and certain
reflex actions such as coughing, sneezing,
swallowing and vomiting.
 It has two main subdivisions.
TWO MAIN PARTS OF AUTONOMIC NS
1. SYMPATHETIC
 It is activated in times of physical or
emotional stress or whenever the body
requires action.
TWO MAIN PARTS OF AUTONOMIC NS
1. SYMPATHETIC
 It controls the “fight-or-flight”
response that you experience during a
stressful situation like the nervousness
you experience when talking in front of
an audience or taking a surprise quiz.
TWO MAIN PARTS OF AUTONOMIC NS
1. SYMPATHETIC

The fight-or-flight response, also known
as the acute stress response, refers to a
physiological reaction that occurs in the
presence of something that is terrifying,
either mentally or physically such as
increased heart rate, sweating, heavy
breathing, increased blood pressure, and
digestive slowdown.
TWO MAIN PARTS OF AUTONOMIC NS
2. PARASYMPATHETIC

it maintains body functions and restores
the body to normal or relaxed mode.

It does the opposite things of the
sympathetic nervous system.
 This way the parasympathetic and
sympathetic nervous systems balance
each other's effects.
TWO MAIN PARTS OF AUTONOMIC NS
2. PARASYMPATHETIC

Parasympathetic response is described as
“rest and digest”, which promotes energy
conservation such as a slower heart rate,
decreased blood pressure, and bronchial
muscle and urinary bladder constriction.
 The Parasympathetic division maintains
body functions and restores the body to
normal or relaxed mode.
Summary:
FUNCTIONS OF THE NERVOUS SYSTEM
1. Collects sensory input from inside the
body and external environment.
2. Process and interpret the sensory
input.
3. Respond appropriately to the sensory
input
Summary:
 The nervous system is the complete
network of nerve cells (neurons).
 It includes the brain, the spinal cord,
the nerves and all the sensory
neurons in the body.
 In short the nervous system is what
makes us human. It allows us to feel,
think, act, live, love etc.
What would happen if we didn’t
have the nervous system?
 The pain message is carried through
neurons and when it reaches the
spinal cord, it orders muscles in your
hand to contract and pull away. ...
 ... But if you didn't have nerves, you
would not feel the pain in your hands
and let them get harmed. That is what
would happen if the nervous system
didn't exist
Common brain and nervous system
problems/disorders:
These neurological disorders can affect memory and
ability to perform daily activities.
1. Alzheimer's disease
 It is an irreversible, progressive brain
disorder that slowly destroys memory
and thinking skills, and eventually the
ability to carry out the simplest tasks.
2. Multiple Sclerosis (MS)
 It is a potentially disabling disease of the
brain and spinal cord.
 The immune system attacks the protective
sheath (myelin) that covers nerve fibers
and causes communication problems
between your brain and the rest of your
body. Eventually, the disease can cause the
nerves themselves to deteriorate or
become permanently damaged.
3. Parkinson's disease
 it is a chronic, progressive, movement
disorder that affects muscle control and
balance. These symptoms gradually
worsen over time.
4. Epilepsy
 It is a CNS (neurological) disorder in which
brain activity becomes abnormal, causing
seizures or periods of unusual behavior,
sensations, and sometimes loss of awareness.
5. Stroke
 It occurs when the blood supply to part of
your brain is interrupted or reduced,
depriving brain tissue of oxygen and
nutrients. Within minutes, brain cells begin
to die.
How can you keep your nervous
system healthy?
Cells of the Brain
 The brain is made up of two types of cells:
nerve cells (neurons) and glia cells.
Glia Cells
 Glia (Greek word meaning glue) is the cells
of the brain that provide neurons with
nourishment, protection, and structural
support.
Cells of the Brain
2. The Nerve Cells “Neurons”
 basic (functional) unit of the nervous system
a.k.a neurons
 There are billions of neurons in the body.
Some exist alone. Others are joined
together to form organs like the brain and
spinal cord. There are 12 to 14 billions of
neurons in one part of the brain alone.
Neurons have dendrites and axons that aid
in transmitting the message.
Brain Processes Electrical Impulses
Neurons Transfer Electrical Impulses
from Brain to All Portions of the Body
Brain is the Control Panel – Neurons
are the Wires to External Devices
(although both portions are composed
of neurons)
Components (Structure) of Neurons
A neuron receives signals via chemicals
called neurotransmitters.
It then transmits the signals, electrically.
Components (Structure) of Neurons
A neuron consists of a cell body or
soma, dendrites, and a single axon.
Neurons have root-like structures, the
dendrites and axons that aid in
transmitting the message.
Components (Structure) of Neurons
1. Cell Body (or soma)
center part of the cell containing the
nucleus and controls cell activities
Components (Structure) of Neurons
2. Axon
Carries impulses away from the cell
body.
Elongated extension of the cell body
End of the axon is divided into
fingerlike projections called axon
terminals.
2. Axon
It carries electrochemical signals from the soma
to other neurons. Axons pass impulses to the
dendrites of other neurons or cell body of
muscle cells.
Axons can be grouped together into cable-like
bundles called nerves.
The axon is surrounded by a series of short,
cylindrical myelin sheaths along its length.
These lie much like beads on a string. If the
sheaths are damaged, the axon cannot transmit
signals properly. This can lead to multiple sclerosis
3. Dendrites
Carries impulses toward the cell body.
Finger-like projections
 An important function of the dendrite
is the integration of various input
signals. A cell may have as many as
200 dendrites carrying impulses
toward the cell body.
 A single dendrite can be over 1m long.
4. Synapse
Synapses are the gaps between the
axons of transmitting neurons and the
dendrites of receptor neurons.
 Electrochemical signals are carried
across the gap by neurotransmitter
molecules.
 These end up at the receptor proteins
located in the ends of dendrites.
5. Myelin sheath
layer of fatty substances enclosing
nerve fibers.
 Insulates axon like a rubber sheath.
6. Nodes of Ranvier
regions where myelin sheath is
absent.
 Allows nerve impulses to jump,
speeding up the transmission of
impulses.
NEUROTRANSMITTER
There are various neurotransmitter
chemicals. Each serves a different
type of neuron.
 Among them are serotonin,
acetylcholine, and dopamine.
NEUROTRANSMITTER
1. Serotonin
 imparts a feeling of well-being.
 It is associated with the central
nervous system, blood platelets, and
the gastrointestinal tract.
NEUROTRANSMITTER
2. Acetylcholine
 relates to the heart and skeletal
musculature.
NEUROTRANSMITTER
3. Dopamine
 may occur in increased levels in
persons of extroverted personalities.
Control of Body Processes
through the Nervous System
The NERVE IMPULSE
 Neurons have the special ability to
carry signals or impulses.
The NERVE IMPULSE
 A nerve impulse is a combination of an
electrical charge and a chemical
reaction, hence it is an electrochemical
signal (gradient) moving along a
neuron.
 A stimulus is any factor in the
environment that may induce a nerve
impulse that initiates physiological
and behavioral changes
 A response is a reaction to a condition
or stimulus.
 To survive, an organism must be able
to respond to a stimulus.
 Reaction time is the length of time
between application of a stimulus and
detection of a response.
Key Concepts:
 When a receptor such as an organ
perceives a stimulus, the impulse is
sent to the brain by the sensory
neurons, transmitting information
from one nerve cell to another
Key Concepts:
 As the message reaches the brain, it
processes the information and
commands an effector such as a
muscle or an organ to respond.
 The message coming from the brain is
sent through the motor neurons to
the organ, gland or muscle..
Key Concepts:
 Any damage in the nervous system
affects the function of other body
parts, since messages are not
properly transmitted throughout the
body.
Thank you 