Download Nervous System

The nervous system:
monitors the internal and
external environments
integrates sensory
information
coordinates involuntary
response of many other
organ systems.
These functions are
performed by cells called
neurons, which are surrounded
and protected by surrounding
cells called neuroglia.
Central Nervous
System
Consists of the
brain and the spinal
cord.
Integrates and
coordinates the
processing of
sensory data and
the transmission of
motor commands.
Intelligence,
memory, and
emotion.
Peripheral
Nervous System
Where all
communications
between the
CNS and the
rest of the body
occurs.
Includes all the
neural tissue
outside the
CNS.
Two types of
neural tissue:
Neurons:
responsible for
information
transfer and
processing.
Neuroglia (glial
cells): provide a
supporting
framework and
act as
phagocytes.
Neurons and Supporting Cells
• Neurons are the basic
structural and functional
units of the nervous system.
• Responds to physical &
chemical stimuli
Enable perception of
sensory stimuli, learning,
memory, and control of
muscles & glands
Cannot divide by mitosis
Supporting cells aid the
functions of neurons
• More abundant than
neurons
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• The cell body is the enlarged
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portion of the neuron that
contains the nucleus.
 Nutrition center, produces
macromolecules
Dendrites are thin, branched
processes
 Provide the receptive area
that transmits electrical
impulses to the cell body.
Axon conducts impulses
away from the cell body.
 Axoplasmic flow
 Axonal transport
Neurons
Sensory Neurons form the afferent
division of the PNS and deliver
information to the CNS.
Motor Neurons stimulate or modify the
activity of a peripheral tissue, organ, or
organ system.
Interneurons (association neurons) may be
located between sensory and motor
neurons; they analyze sensory inputs and
coordinate motor outputs.
Neurons maybe described as unipolar,
bipolar, or multipolar.
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Supporting Cells/ Neuroglia
Microglia- protect the nervous system by
destroying invasive microorganisms and
other materials that could harm the
system
Astrocytes - maintenance of the nervous
system; absorb harmful chemicals in the
environment (Ex. Potassium)
Ependymal cells- line the central cavities
of the brain and spinal cord; act as a
semi-permeable lining between the
cavities and normal tissue
 Oligodendrocytes- responsible for
the myelination of CNS axons.
Synapse: site where intercellular
communication occurs through the release of
chemical called neurotransmitters.
Neuroeffector junction: synapse where neurons
communicate with other cell types.
Neural communication moves from the
presynaptic neuron to the postsynaptic neuron
across the synaptic cleft.
Neuronal pools: groups of interconnected
neurons with specific functions.
Divergence: spread of information from one
neuron to several neurons or from one neuronal
pool to several pools.
Convergence: several neurons synapse on the
same postsynaptic neuron.
The CNS is made up of the
spinal cord and the brain.
The Meninges.
Meninges: special covering membranes that
protect and support the spinal cord and the
delicate brain.
The cranial meninges (dura mater, arachnoid,
and pia mater) are connected with those of the
spinal cord, the spinal meninges.
The dura mater covers the brain and the
spinal cord.
The epidural space separates the spinal dura
mater from the walls of the vertebral canal.
Cerebrospinal fluid (CSF) acts as a shock
absorber and a diffusion medium for dissolved
gases, nutrients, chemical messengers, and
waste products.
Pia mater: bound to the underlying neural
tissue.
 Each cerebral hemisphere receives sensory information and generates
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motor commands that concern the opposite side of the body.
Primary motor cortex: directs voluntary movement.
Primary sensory cortex: receives somatic sensory information from
touch, pressure, pain, and temperature receptors.
The left hemisphere is usually the categorical hemisphere, which
contains the general interpretive and speech centers and is responsible
for language-based skills.
The right hemisphere, or representational hemisphere, is concerned
with spatial relationships and analyses.
The diencephalon provides the switching and relay centers needed to
integrate the conscious and unconscious sensory and motor pathways.
It’s made up of the epithalamus, which contains the pineal gland and
choroid plexus (a vascular network that produces CSF), the thalamus,
and the hypothalamus.
Nerves
Type
Function
I
Olfactory
Sensory
Smell
II
Optic
Sensory
Vision
(Contain 38% of
all the axons
connecting to the
brain.)
III
Oculomotor
Motor
eyelid and eyeball
muscles
IV
Trochlear
Motor
eye muscles
V
Trigeminal
Mixed
VI
Abducens
Sensory: facial and
mouth sensation
Motor: chewing
Motor
Eyeball movement
VII
Facial
Mixed
VIII
Vestibulocochlear
Sensory
Sensory: taste
Motor: facial muscles
and
salivary glands
Hearing, balance,
position, and
movement
IX
Glossopharyn
geal
Mixed
Sensory: taste
Motor:
swallowing
Mixed
Main nerve of
the
Parasympathet
ic Nervous
System (PNS
)
XI
Accessory
Motor
Swallowing;
moving head
and shoulder
XII
Hypoglossal
Motor
Tongue
muscles
X
Vagus
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Alzheimer Disease
Alzheimer’s disease is an
irreversible, progressive brain
disease that slowly destroys
memory and thinking skills, and
eventually even the ability to
carry out the simplest tasks.
Most common cause of
dementia– the loss of cognitive
function
Results from an increase in the
production or accumulation of a
specific protein (beta-amyloid
protein) in the brain that leads
to nerve cell death.
Alois Alzheimer, a German physician
Memory loss
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Forgetting recently
learned information
Confusion with time or
place
Trouble understanding
visual images
Problems with words in
speaking or writing
Changes in mood and
personality
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An interview or
questionnaire to
identify past medical
problems,
difficulties in daily
activities, etc.
Physical
examination,
including hearing &
sight
blood and urine
tests
Neuropsychological
testing
Brain-imaging scan
PiB PET scan comparing brains of people
with and without Alzheimer's disease.
Damaged or lost brain tissue cause some
messages to not transmit.
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Prognosis, Treatment, and Prevention
Alzheimer’s disease naturally progresses and worsens
overtime
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Some die within 8 to 10 years, some live as long
as 25 years.
Person will die when all bodily systems fail
because of the disease.
There is currently no cure for Alzheimer’s but there
are drug treatments to slow cognitive symptoms &
non-pharmacological therapies to manage behaviors.
Physical activity effectively reduces the probability of
Alzheimer’s disease and other dementias.
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Eating healthy, keeping the brain stimulated,
sleeping to restore memory, and reducing stress
also help prevent or delay Alzheimer’s disease.