Watch Youtube Video
Introduction to Nervous System…….
https://youtu.be/dah-4mtAnsQ
Nervous System

The nervous system is a complex network of nerves and cells that carry
messages to and from the brain and spinal cord to various parts of the
body.

The nervous system is divided into the Central nervous system and
Peripheral nervous system.
Watch Youtube Video
Nervous System…….
https://youtu.be/sjyI4CmBOA0
Neuron
Nerve cell
-Transmits a message from one
cell to another
-Has a nucleus, cytoplasm, and
cell membrane
-
Dendrites
Nerve cell processes that
carry impulse to cell
body…may be one or more
Watch the following video and
answer these questions:
 1.
What is a neuron?
 2.
What are the main parts of a neuron?
 3.
What is the path of action potential
down a neuron?
Watch Youtube Video
Basic Neuron…….
https://youtu.be/mZdjQXrnTRo
 Axon
 -Carries
impulses away
from the cell
body
 -Only
one on a
neuron
Myelin Sheath
•Myelin is a fatty
substance that
protects axon
•speeds
transmission
along axon Called neurilemma
SYNAPSE
A space between neurons, messages
go from one cell to another.
Watch Youtube Video
Synapse…….
https://youtu.be/WmTXiLndbsc
NERVE IMPULSE
 A STIMULUS creates
an IMPULSE.
Impulse to dendrite
to cell body
to axon
to synapse (by
neurotransmitters)
to the next neuron
(or muscle or gland).
Watch Youtube Video
How a Neuron fires…….
https://youtu.be/C4Gt322-XxI
SENSORY NEURONS
(AFFERENT)
 Emerge from the
skin or sense
organs.
 Carry impulses to
spinal cord and
brain.
MOTOR
NEURONS
(EFFERENT)
 Carry
messages
from brain
and spinal
cord to
muscles and
glands.
ASSOCIATIVE NEURONS
(INTERNEURONS)
 Carry impulses
from sensory
neurons to
motor neurons.
Watch Youtube Video
Nervous System…….
https://youtu.be/M1E9Lm16cUs
NEUROGLIA
 Act as the “helper” cells
of the nervous system.
 Each neuron in the
body is surrounded by
anywhere from 6 to 60
neuroglia that protect,
feed, and insulate the
neuron.
 They that insulate,
support and protect the
neurons, nerve glue.
Divisions of the Nervous System
CENTRAL
NERVOUS
SYSTEM
Consists of
the brain
and spinal
cord
Central Nervous System

The Central nervous system is made up of the brain and spinal cord
and The Peripheral nervous system is made up of the Somatic and
the Autonomic nervous systems.

Communication and coordination system of the body

Seat of intellect and reasoning.

Consists of the brain, spinal cord, and nerves.
Divisions of the Nervous System
PERIPHERAL
NERVOUS
SYSTEM
Consists of the
autonomic and
somatic
Peripheral Nervous System (PNS)
Includes all of the
parts of the
nervous system
outside of the
brain and spinal
cord. These
parts include all
of the cranial
and spinal
nerves, ganglia,
and sensory
receptors.

Somatic Nervous System
(SNS) is a division of the PNS
that includes all of the
voluntary efferent neurons.
The SNS is the only
consciously controlled part of
the PNS and is responsible for
stimulating skeletal muscles in
the body.



Autonomic Nervous
System (ANS) is a division
of the PNS that includes all of
the involuntary efferent
neurons. The ANS controls
subconscious effectors such as
visceral muscle tissue, cardiac
muscle tissue, and glandular
tissue. Peripheral nerves and ganglia
(ie: -Supplies heart muscle,
smoother muscle and
secretory glands
-automatic responses to injury
like shock and increased heart
rate)
Divisions
of
Peripheral
Nervous
System
(PNS)
AUTONOMIC NERVOUS SYSTEM
 Regulates activities of visceral organs (i.e.
beating of heart)
Not subject to conscious control
Has two divisions:
SYMPATHETIC NERVOUS SYSTEMthe “fight or flight” system
&
PARASYMPATHETIC NERVOUS
SYSTEM
AUTONOMIC NERVOUS SYSTEM
SYMPATHETIC NERVOUS SYSTEMthe “fight or flight” system- when the body
perceives danger, SNS sends message to
adrenal medulla (above kidney) to secrete
adrenaline - heartbeat increases, resp
rate increases, etc
•
PARASYMPATHETIC NERVOUS
SYSTEM counters SNS – decreases heart
rate, decreases respiratory rate, etc
REFLEX
 Unconscious and involuntary
 In a simple reflex, only a sensory nerve
and motor nerve involved – example
“knee-jerk” reflex
Watch Youtube Video
Central Nervous System…….
https://youtu.be/-s8yEhRZgvw
The Brain
 3lb
mass of soft
nervous tissue
 100
billion neurons
 Protected
by skull, 3
membranes called
meninges, and
cerebrospinal fluid
(shock absorber)
 Adequate
blood supply is
needed, brain tissue will die in
4-8 mins without O2
 Divided
into 4 major parts:
cerebrum, diencephalon (near
midbrain), cerebellum, brain
stem
Coverings of the Brain & Spinal Cord
(MENINGES)

The meninges are the
protective coverings of the
central nervous system
(CNS) (coverings of the
brain and spinal cord).

. They consist of three
layers:
dura mater,
arachnoid mater, and
pia mater.
Watch Youtube Video
Brain…….
https://
 DURA
MATER- outer brain
covering, lines inside of skull,
tough, fluid-containing - dense
fibrous connective tissue
 Layers
= dura mater, subdural,
arachnoid, subarachnoid, pia
mater
Coverings cont’d

Subdural space
 is between the dura
and arachnoid space
Next layer is the
Arachnoid layer
- middle layer –
resembles fine cob
web
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Nervous System…….
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Nervous System…….
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Nervous System…….
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Coverings cont’d
PIA MATER


innermost layer of the meninges
covers the brain’s surface,
comprised of blood vessels held
together by connective tissue
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Nervous System…….
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Ventricles of the Brain
Brain contains four cavities filled
with cerebrospinal fluid called
CEREBRAL VENTRICLES.
Ventricles of the Brain (cont.)
CHOROID PLEXUS- network of blood
vessels lining the ventricles which
helps in the formation of
cerebrospinal fluid.
CEREBROSPINAL FLUID
 Forms inside ventricles of the brain.
 Serves as a liquid shock absorber
Watch Youtube Video
Nervous System…….
https://
BLOOD-BRAIN BARRIER- choroid
plexus capillaries prevent substances
(like drugs) from penetrating brain
tissue – this makes infections, like
meningitis, difficult to cure.
LUMBAR PUNCTURE- removal of
CSF from spinal canal, needle
puncture between 3rd and 4th lumbar
vertebrae.
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Nervous System…….
https://
CEREBRUM
Largest part of the brain
Divided into R and L hemispheres
by deep groove
CONVULTIONS- elevated folds
on the surface of the cerebrum,
they increase the surface area of
the brain
SULCI - fissure or grooves separating
cerebral convolutions
Divided into four lobes – FRONTAL
(voluntary muscle movement),
PARIETAL, OCCIPITAL and
TEMPORAL
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Nervous System…….
https://
CEREBRAL FUNCTION
Conscious thought,
judgment, memory,
reasoning, and will
power.
- responsible for
maintaining
consciousness,
decision making,
recalling information
and normal speech
These people were not
using their cerebrum.
DIENCEPHALON

Located between cerebrum and
midbrain
 Composed of THALAMUS and
HYPOTHALAMUS
Vital functions of the
hypothalamus:
1. Autonomic nervous control
2. Temperature control
3. Appetite control
4. Emotional state
5. Sleep control




CEREBELLUM
2nd largest part of brain
Composed of two
hemispheres
below the cerebrum
Controls all body functions
related to skeletal muscles,
including:
o Balance, walking
o Muscle tone
o Coordination of muscle
movements
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Nervous System…….
https://

Controls all body functions
related to skeletal muscles,
including:
Balance, walking
o Muscle tone
o Coordination of muscle
movements
o
BRAIN STEM


Made up of PONS, MEDULLA and MIDBRAIN
Pons – in front of cerebellum, between midbrain
and medulla – contains center that controls
respiration
 Midbrain – controls vision and hearing
 Medulla oblongata – bulb-shaped structure
between pons and spinal cord, inside the
cranium above foramen magnum (opening in
vertebral column)
 - Responsible for:
1. Heart rate
Click for picture…
2. Blood pressure
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Nervous System…….
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SPINAL CORD

Begins at foramen
magnum and continues
down to 2nd lumbar
vertebrae

White and soft, in spinal
canal

Surrounded by
cerebrospinal fluid
FUNCTIONS AS:
1.
Reflex center
2.
Conduction pathway to
and from the brain
Injury to spinal cord =
difficulty with movement
(paraplegia – paralysis of legs)
and problems breathing
Peripheral Nervous System

All of the nerves outside the
central nervous system
NERVES

Contains sensory and motor
nerves (afferent and
efferent)
Cranial Nerves
12 pairs
Begin in the brain
Designated by number and name
On
Old
Olympus’
Towering
Top
A
Finn
And
German
Vault
And
Hop
Watch Youtube Video
Learn the 12 Cranial Nerves…….
https://youtu.be/kqNFmBGHs2I
SPINAL NERVES

Originate at spinal cord and go through
openings in vertebrae

31 pairs of spinal nerves

All are mixed (afferent and motor) nerves

Named in relation to their location on the spinal
cord
Disorders of the Nervous System
MENINGITIS

Inflammation of the lining of the brain
and spinal cord

May be bacterial or viral

Symptoms- headache, fever and stiff
neck, nausea and vomiting

In severe form, may lead to paralysis,
coma and death

If bacterial, may be treated with
antibiotics

Dx by removing csf with a needle =
lumbar puncture
EPILEPSY
Seizure disorder of the brain, characterized by
recurring and excessive discharge from neurons
Seizures believed to be result of spontaneous,
uncontrolled electrical activity of neurons
Cause – Uncertain
Victim may have hallucinations and seizures
Grand mal – severe, convulsive seizure
Petit mal - milder
Watch Youtube Video
Epilepsy…….
https://youtu.be/iYkWt1erux4
Watch Youtube Video
Epilepsy First Aid…….
https://youtu.be/men1or169Xo
CEREBRAL PALSY
•
•
•
•
•
Disturbance in voluntary muscular action
due to brain damage.
May be due to birth injury or abnormal
brain development
Spastic Quadriplegia- spastic paralysis in
all four limbs.
Sx- head rolling, grimacing,
difficult speech and swallowing
No impairments of intellect.
POLIOMYELITIS
•
Viral disease of nerve
pathways of spinal cordcausing progressive muscle
weakness leading to
paralysis
• Almost eradicated in USA
(vaccine)
DEMENTIA
•
Loss of 2 areas of complex
behavior, such as
languages, memory, visual
and spatial abilities, or
judgment
• Interferes with person’s daily
HYDROCEPHALUS
•
•
•
•
Increased volume of cerebrospinal fluid
within ventricles of the brain.
Usually, blockage in 3rd and 4th ventricle
Enlargement of the head, usually noticed
at birth.
Bypass or shunt performed to relieve
pressure.
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Nervous System…….
https://
ALZHEIMER’S DISEASE

Progressive disease that
begins with problems
remembering – characterized
by early senility, confusion,
and loss of recognition of
persons

Nerve endings in cortex of
brain degenerate and block
signals that pass between
nerve cells

Abnormal fibers build up
creating tangles




Cause – Unknown
1st stage (2-4 yrs) involves confusion,
short-term memory loss, anxiety, poor
judgment
2nd stage (2-10 yrs) increase in memory
loss, logic problems, and loss of social
skills
3rd stage (1-3 yrs) inability to recognize
oneself, weight loss, seizures, mood
swings and aphasia
PARKINSON’S DISEASE
• Symps - tremors,
shuffling gait, pillrolling, and muscular
rigidity.
• Decrease in
neurotransmitter
dopamine
• RX- L-dopa and other
drugs to treat
symptoms.
(MS) Multiple Sclerosis- autoimmune, Chronic inflammatory disease of CNS Immune cells attack myelin sheath of axon-myelin sheath destroyed, leaving
scar tissue on nerve cells…transmission of nerve impulses blocked.
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Nervous System…….
https://
•
Cause- UNKNOWN
•
Sx- weakness of extremities,
numbness, double
vision,
nystagmus, speech problems, loss of
coordination, possible paralysis.
•
Typically strikes young adults age 2040, mostly women
•
Rx- Avonex- slows progression
Cerebral Vascular Accident

Stroke or CVA
 Interruption of blood
and O2 to the brain –
blockage of blood to
the brain
 Tissue death
 Third leading cause
of death in USA
PARALYSIS- loss of
power of motion or
sensation
HEMIPLEGIAparalysis on one
side of the body
 (“hemi” means half)
Risk Factors
 Smoking
 Hypertension
 Heart disease
 Family history
Causes of CVA
90% caused by blood clots
Clots lodge in carotid arteries, blocking the
flow of blood to the brain
10% caused by ruptured blood vessels in
the brain
SYMPTOMS








Hemiplegia on the opposite side
of the body
Sudden, severe headache
Dizziness
Sudden loss of vision in one
eye
Aphasia
Dysphasia
Coma
Possible death