Transcript The Nervous System - McGraw Hill Higher Education

PowerPoint® to accompany
Medical Assisting
Chapter 27
Second Edition
Ramutkowski  Booth  Pugh  Thompson  Whicker
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
The Nervous System
Objectives:
27-1 Explain the difference between the central
nervous system and the peripheral nervous
system.
27-2 Describe the functions of the nervous system.
27-3 Describe the structure of a neuron.
27-4 Describe the function of a nerve impulse and
how a nerve impulse is created.
27-5 Describe the structure and function of a synapse.
27-6 Describe the function of the blood-brain barrier.
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The Nervous System
Objectives:
27-7 Describe the structure and functions of meninges.
27-8 Describe the structure and functions of the spinal
cord.
27-9 Define reflex and list the parts of a reflex arc.
27-10 List the major divisions of the brain and give the
general functions of each.
27-11 Describe the differences between the somatic
nervous system and autonomic nervous system.
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The Nervous System
Objectives:
27-12 Explain the two divisions of the autonomic
nervous system.
27-13 Explain the functions of the cranial and spinal
nerves.
27-14 Describe the location and function of
cerebrospinal fluid.
27-15 Describe various disorders of the nervous system
and how they are diagnosed and treated.
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Introduction
Nervous system is a
highly complex system
divided into two major
parts;
Controls all other organs
systems and is important
for maintaining balance
within those systems.
 Central nervous system
(CNS)
 Peripheral nervous
system.
Disorders of the nervous system are numerous and often very
difficult to diagnose and treat because of the complexity of this
system.
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General Functions of the
Nervous System
 Detect and interpret
sensory information,
 Make decisions about
the sensory
information that is
received,
 Carry out motor
functions based on
the decisions made.
For example, if you feel
pain, your brain might
decide you need to move
away from the painful
stimulus.
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Neuron Structure
 Transmit
electrochemical
messages called nerve
impulses to other
neurons and effectors
(muscles or glands)
 Neurons lose their
ability to divide
 When destroyed by
disease, they cannot be
replaced
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Neuron Structure (cont.)
Neurons have cell
body processes called
nerve fibers that
extend from the cell
body.
 Dendrites - short function is to receive
information (nerve
impulses) for the neuron
 Axons - long - function
is to send information
(nerve impulses) away
from the cell body.
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Nerve Impulse
 Nerve impulse is the flow of electric current along
the axon membrane
 At rest, or in its polar state, more sodium (Na+) is on
the outside of the membrane, which makes the
outside positive and the inside negative.
 When sodium moves into the cell, the membrane
depolarizes, which means that the inside becomes
more positive.
 The membrane repolarizes when potassium (K+) and
later sodium move to the outside of the cell
membrane.
9
Synapse
 Synaptic knobs contact dendrites, cell bodies and
the axons of other neurons
 Synaptic knob is contacting is called a postsynaptic
structure.
 Within synaptic knobs are vesicles or small sacs that
contain chemicals called neurotransmitters. When
the nerve impulse reaches the synaptic knobs, the
neurotransmitters are released onto postsynaptic
structures.
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Neurotransmitters
 Functions:
 Causes muscles to contract or relax
 Causes glands to secrete products
 Activates neurons to send nerve impulses,
inhibiting neurons from sending nerve
impulses.
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Apply Your Knowledge
What is the function of a dendrite?
12
Apply Your Knowledge -Answer
What is the function of a dendrite?
Dendrite’s function is to receive information
(nerve impulses) for the neuron.
13
Central Nervous System
 Includes the spinal cord and brain.
 Has a blood-brain barrier:
 Barrier prevents certain substances from
entering the tissues of the CNS
 Tight capillaries form the blood-brain
barrier.
Meninges are membranes that protect the
brain and spinal cord.
14
Cerebrospinal fluid
 Location:
 Between the arachnoid mater and
pia mater is an area called the
subarachnoid space
 Function:
 Cushions the CNS
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Spinal Cord
 Slender structure that is continuous with the
brain
 Descends into the vertebral canal and ends
around the level of the first or second lumbar
vertebra.
 31 spinal segments:





8 cervical segments
12 thoracic segments
5 lumbar segments
5 sacral segments
1 coccygeal segment
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Spinal Cord (cont.)
Name the spinal
segments and tell how
many of each segment
are present on the spinal
cord.
8 cervical segments
12 thoracic segments
5 lumbar segments
5 sacral segments
1 coccygeal segment
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Spinal Cord –
Gray and White Matter
 Gray matter - inner tissue with darker color
 contains neuron cell bodies and their dendrites
 divisions are called horns and the divisions of
the white matter are called columns (funiculi)
 columns contain groups of axons called nerve
tracts
 central canal runs down the entire length of the
spinal cord through the center of the gray
matter
 White matter - the outer tissue
 contains myelinated axons
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Spinal Cord - Ascending and
Descending Tracts
 Function of the spinal cord
is to carry sensory
information to and from
the brain
 Ascending tracts - carry
sensory information up to
the brain
 Descending tracts - carry
motor information down
from the brain to muscles
and glands
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Spinal Cord Reflexes
 Function of the spinal cord is to participate in
reflexes
 Reflex - a predictable, automatic response to
stimuli
Receptor
Sensory Neurons
Interneurons
Effectors
Motor Neurons
20
Apply Your Knowledge
What are the descending tracts of the
spinal cord?
21
Apply Your Knowledge -Answer
What do the descending tracts of the
spinal cord do?
Descending tracts carry motor
information down from the brain
to muscles and glands
22
The Brain
Four Parts:




Cerebrum
Diencephalons
Brain stem
Cerebellum
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The Brain - Cerebrum
 Largest part of the
brain
 Two halves cerebral
hemispheres
 Thick bundle of
nerve fibers called
the corpus callosum
connect the two
hemispheres
 Lobes
 Frontal
 Parietal
 Temporal
 Occipital
 Cortex
 Ventricles
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The Brain - Diencephalons
Located between the cerebral hemispheres
and is superior to the brain stem
 Thalamus - relay
station for
sensory
information that
heads to the
cerebral cortex
for interpretation
 Hypothalamus maintains balance
by regulating many
vital activities such
as heart rate, blood
pressure, and
breathing rate.
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The Brain - Brain stem
Connects the cerebrum to the spinal cord
Midbrain controls both
visual and
auditory reflexes
Pons - regulates
breathing
Medulla oblongata controls many vital
activities such as
heart rate, blood
pressure, and
breathing
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The Brain - Cerebellum
 Inferior to the
occipital lobes of
the cerebrum
 Posterior to the
pons and medulla
oblongata
 Coordinates
complex skeletal
muscle
contractions that
are needed for
body movements
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Apply Your Knowledge
The patient has had trauma to the pons
of the brain. What type of problems
would you see in the patient?
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Apply Your Knowledge -Answer
The patient has had trauma to the pons
of the brain. What type of problems
would you see in the patient?
The patient could not breath
without assistance.
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Preventing Brain and Spinal
Cord Injuries
 Always wear
appropriate protective
gear while playing any
sport.
 Avoid diving headfirst
into unknown waters.
 Always wear your
safety belt.
 Follow safety rules on
playgrounds.
 Make sure children use
car seats that are
appropriate for their
age and weight.
 Be familiar with ways
to get help quickly in
emergencies.
 Follow traffic rules and
signs while walking,
biking, or driving.
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Peripheral Nervous System
Consists of nerves that branch off
the CNS.
These nerves are called peripheral
nerves and are classified in 2 types:
 Cranial nerves
 Spinal nerves
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Cranial Nerves – 12 Sets
I. Olfactory nerves carry smell information
to the brain for interpretation.
II. Optic nerves carry visual information to
the brain for interpretation.
III. Oculomotor nerves are found within the
muscles that move the eyeball, eyelid and
iris.
IV. Trochlear nerves act in the muscles that
move the eyeball.
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Cranial Nerves (cont.)
V. Trigeminal nerves carry sensory
information from the surface of the eye, the
scalp, facial skin, the lining of the gums, and
the palate to the brain for interpretation.
They also are found within the muscles
needed for chewing.
VI. Abducens nerves act in the muscles that
move the eyeball.
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Cranial Nerves (cont.)
VII.
Facial nerves are found in the muscles
of facial expression as well as in the
salivary and tear glands. These nerves
also carry sensory information from the
tongue.
VIII. Vestibulocochlear nerves carry hearing
and equilibrium information from the
inner ear to the brain for interpretation.
34
Cranial Nerves (cont.)
IX. Glossopharyngeal nerves carry sensory
information from the throat and tongue to the
brain for interpretation. They also act in the
muscles of the throat.
X.
Vagus nerves carry sensory information from
the thoracic and abdominal organs to the brain
for interpretation. These nerves are also found
within the muscles in the throat, stomach,
intestines and heart.
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Cranial Nerves (cont.)
XI. Accessory nerves are found within the
muscles of the throat, neck, back, and
voice box.
XII. Hypoglossal nerves are found within the
muscles of the tongue.
36
Spinal Nerves
 Spinal nerves are peripheral nerves that originate
from the spinal cord.
 31 pairs of spinal nerves:





8 pairs of cervical nerves (C1 through C8)
12 pairs of thoracic nerves (T1 through T12)
5 pairs of lumbar nerves (L1 through L5)
5 pairs of sacral nerves (S1 through S5)
One pair of coccygeal nerves (Co)
37
Somatic and Autonomic
Nervous Systems
 Consists of nerves that connect the CNS to skin
and skeletal muscle.
 Somatic nervous system - “voluntary” nervous
system because it controls skeletal muscles, which
are under voluntary control.
 Autonomic nervous system consists of nerves that
connect the CNS to organs and other structures
such as the heart, stomach, intestines, glands,
blood vessels, and bladder (among others) “involuntary” nervous system.
38
Neurologic Testing
 Typical neurologic examination:




State of consciousness
Reflex activity
Speech patterns
Motor patterns
39
Diagnostic Procedures
Common diagnostic procedures
Lumbar Puncture  Computerized
Magnetic
Tomography (CT)
Resonance
Scan
Imaging (MRI).
 Electroencephalogram
Positron Emission
(EEG)
Tomography
 X Ray
(PET) Scan
40
Reflex Testing
Biceps reflex - The absence of
this reflex may indicate spinal cord
damage in the cervical region.
 Knee reflex - The absence of this
reflex may indicate damage to
lumbar or femoral nerves.
 Abdominal reflexes - These
reflexes are used to evaluate
damage to thoracic spinal nerves.

41
Apply Your Knowledge
What is the somatic nervous system?
42
Apply Your Knowledge -Answer
What is the somatic nervous system?
Somatic nervous system (“voluntary”)
nervous system because it controls skeletal
muscles, which are under voluntary control
43
Diseases and Disorders of the
Nervous System
 Alzheimer's Disease - a progressive,
degenerative disease that occurs in the brain.
 Amyotrophic Lateral Sclerosis (ALS) - a
fatal disorder characterized by the
degeneration of neurons in the spinal cord
and brain.
 Bell's Palsy is a disorder in which facial
muscles are very weak or totally paralyzed.
44
Diseases and Disorders of the
Nervous System (cont.)


Brain Tumors and
Cancers - abnormal
growths in the brain
Epilepsy and Seizures
- occur when parts of
the brain receive a
burst of electrical
signals that disrupt
normal brain
functioning.

Guillain-Barré
Syndrome - a disorder
in which the body's
immune system attacks
part of the peripheral
nervous system.
45
Diseases and Disorders of the
Muscular System
Headaches affect almost
everyone at some point in
their life
 Tension Headaches
 Cluster
 Migraine
Multiple Sclerosis (MS) a chronic disease of the
central nervous system
in which myelin is
destroyed.
Stroke - brain cells die due
to an inadequate blood
flow.
46
Diseases and Disorders of the
Muscular System (cont.)


Meningitis is an
inflammation of the
meninges.
Neuralgias are a
group of disorders
commonly referred
to as nerve pain


Parkinson's
Disease is a motor
system disorder
Sciatica occurs
when the sciatic
nerve is damaged.
47
Apply Your Knowledge
The doctor has told your patient she has
had a stroke. How would you explain
this to the family?
48
Apply Your Knowledge -Answer
The doctor has told your patient she has
had a stroke. How would you explain
this to the family?
A stroke happens when brain cells are
damaged or die due to an inadequate blood
flow.
49
Summary
Medical Assistant
Functions of the nervous system include detecting and
interpreting sensory information, making decisions about
that information, and responding to and carrying out motor
functions based on those decisions.
Knowledge of this system is essential when assisting the
physician during a neurologic exam.
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End of Chapter
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