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Chapter 9
Nervous System
https://www.youtube.com/watch?v=qPix_X-9t7E
The Nervous System
Central Nervous System
Brain
Spinal Cord
Peripheral Nervous System
Cranial Nerves
Spinal Nerves
Autonomic Nervous System
Sympathetic Nerves
Parasympathetic Nerves
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Introduction
Nervous system:
• Complex: 10 billion nerve cells
• Voluntary and involuntary functions
• Nerves carry electrical messages
• External and internal receptors
2
Nervous System
Two major divisions:
• Central nervous system
– Brain
– Spinal cord
• Peripheral nervous system
– cranial nerves: Cranial nerves carry electrical impulses
between the brain and the head and neck (except
vagus nerve).
– spinal nerves: Spinal nerves carry impulses between
the spinal cord and the chest, abdomen, and
extremities.
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Vagus Nerve
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General Structure of the Nervous
System
• Cranial and spinal nerves
– Sensory nerves carry messages toward the brain.
– Motor nerves carry messages from the brain.
– Mixed nerves carry both sensory and motor
fibers.
–
• Sensory receptors
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General Structure of the Nervous
System (cont’d.)
Autonomic nervous system:
• Carries impulses from the central nervous
system to organs.
• The autonomic nervous system contains a large
group of nerves that function automatically.
• It controls heart, blood vessels, glands, and
involuntary muscles like intestines, and hollow
organs such as stomach and urinary bladder.
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Automomic Nervous System
• Sympathetic nerves stimulate body under
stress.
• Parasympathetic nerves balance sympathetic
system.
– Slow heart rate
– Lower blood pressure
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Divisions of the Central and
Peripheral Nervous System
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Neurons, Nerves, and Glia
Neuron = individual nerve cell
• Dendrite – branching fibers of neuron
• Cell nucleus
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Neurons, Nerves, and Glia
• Axon – carry impulses away
– Myelin sheath – fatty tissue that covers
the axon giving it a white color (white
matter)
– Gray Matter – cell bodies of neurons not
covered with a myelin sheath.
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Neurons, Nerves, and Glia
• Synapse – space where nervous impulse jumps from
one neuron to another
• Terminal end fibers - (secrete neurotransmitters)
• Neurotransmitters - transfer impulse across synapse
• Ganglia - small clusters of nerve cell bodies outside
the brain and spinal cord.
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Neurotransmitters – chemicals that control
the transfer of an impulse across the synapse
•
•
•
•
•
•
Acetylcholine
Norepinephrine
Epinephrine
Dopamine
Serotonin
Endorphins
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The Brain– Controls body activities,
weighs about 3 lbs
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The Brain
• The brain is divided into right and left
hemispheres.
• The brain consists of four major lobes,
including the frontal lobe, parietal lobe,
temporal lobe, and occipital lobe.
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The Cerebrum
– Largest section of brain
– Surface has nerve cells called cerebral
cortex.
– Manages speech, vision, smell,
movement, hearing, and thought
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Cerebral Cortex
• the outer layer of the cerebrum
(the cerebral cortex ), composed of folded
gray matter and playing an important role
in consciousness
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Cerebrum
• Spaces in the middle of the cerebrum are
called ventricles.
• Ventricles contain cerebrospinal fluid
(CSF). This fluid cushions the brain.
• CSF can be removed for testing or relief of
pressure on the brain.
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The Brain
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The Brain
• Cerebellum
– Coordinates voluntary movements
– Maintains balance
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The Brain
• Thalamus
– Integrates and monitors impulses from skin
(pain)
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• Hypothalamus
– Controls body temperature, sleep, appetite,
sexual desire, and emotions
– Regulates release of hormones from
pituitary gland
– Monitors sympathetic and parasympathetic
nervous systems
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The Brain
The Brainstem
• Pons
– Bridges cerebrum and cerebellum with rest of
the brain
– Houses nerves for face and eyes
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The Brainstem
• Medulla oblongata
– Connects spinal cord to brain
– Nerve tracts from side to side
– Regulates:
• Blood vessels
• Heart
• Respiratory system
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Pons and Medulla
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Thyroid Gland
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The Spinal Cord and Meninges
Spinal cord
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• The spinal cord is the column of nervous
tissue from the medulla oblongata to
second lumbar vertebra.
• It serves as a pathway for impulses to and
from the brain.
• The inner section of the cross-section of
the spinal cord is gray matter.
• The outer section of the cross-section of
the spinal cord is white matter.
• What is the difference between efferent
and afferent neurons?
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Meninges
Meninges
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• Meninges are the three layers of
connective tissue membranes that
surround the brain and spinal cord.
• What is the function of the outer dura
mater? (channels blood to brain tissue)
• What fluid lies between the arachnoid
membrane and the subarachnoid space?
• The inner pia mater offers a rich supply of
blood vessels.
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Meningitis
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Combining Forms – p. 419
• Cephal/o
head
• Cerebr/o
cerebrum
• dur/o
dura mater
• Encephal/o
brain
• Gli/o
glia (nervous
tissue)
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Combining Forms – p. 419
• Mening/o
• Meningi/o
meninges
• Myel/o
spinal cord
• Neur/o
nerve
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Combining Forms
• comat/o
• esthesi/o,
• esthesi/a
• kines/o, -kinesia
Deep sleep
Feeling, nervous
sensation
(anesthesia
without this
feeling)
movement
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Suffixes
• -paresis
partial paralysis -
• -phasia
speech
• -plegia
paralysis -
hemiparesis
quadraplegia
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Suffixes
• -asthenia
weakness
• alges/o, algesia
sensitivity to pain
• Algia
pain
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QUICK QUIZ:
3. Which term means nerve
pain?
A.
B.
C.
D.
cephalgia
analgesia
hypalgesia
neuralgia
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Pathologic Conditions
• Hydrocephalus – abnormal
accumulation of fluid in the brain
• Spina bifida
–Spina bifida cystica
–Spina bifida occulta
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Spina Bifida
•Spina bifida occulta is the most common
and least severe spinal cord defect.
•Incomplete closure of one or more
vertebrae without protrusion of spinal cord
or meninges. Spinal cord is covered with a
layer of skin.
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Spina Bifida
•Spina bifida cystica has two classifications:
– Meningocele—sac contains only
meninges and cerebrospinal fluid (CSF).
– Meningomyelocele―sac contains
meninges, CSF, and a portion of the
spinal cord.
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Meningomyelocele
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Degenerative, Movement, and Seizure
Disorders
• Alzheimer disease
(AD)
• Amyotrophic lateral
sclerosis (ALS)
• Epilepsy
• Huntington disease
• Multiple sclerosis (MS)
• Myasthenia gravis
(MG)
• Palsy
• Parkinson disease
• Tourette syndrome
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Bell Palsy
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Infectious Disorders
• Herpes zoster (shingles)
• Meningitis
• Human immunodeficiency virus (HIV)
encephalopathy
52
• Shingles, also known as zoster or herpes
zoster, is a painful skin rash caused by the
same virus responsible for chicken pox:
the varicella zoster virus. Even if you
hadchicken pox in the past, you can still
contract shingles
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Brain Tumor
• Glioblastoma multiforme (GBM) is
the most common and deadliest
of malignantprimary brain tumors in
adults and is one of a group
of tumors referred to as gliomas.
Classified as a Grade IV (most serious)
astrocytoma, GBM develops from the
lineage of star-shaped glial cells, called
astrocytes, that support nerve cells.
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Neoplastic Disorders
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Traumatic Disorders
• Cerebral concussion:
–Temporary brain dysfunction after
injury, usually clears within 24
hours
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Cerebral Contusion
Bruising of brain
tissue through
direct trauma to
head
– Neurological
deficits persist
longer than 24
hours
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CVA cerebral vascular accident –
• Thrombotic — blood clot in artery
leaving to the brain
• Embolic — dislodged clot that travels to
cerebral arteries
• Hemorrhagic — a blood vessel, such as
the cerebral artery breaks, and bleeding
occurs
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Vascular Disorders
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TIA
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Clinical Procedures
X-ray Tests
–Cerebral angiography
–Computed tomography (CT) of the
brain
–Myelography
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Clinical Procedures
–MRI - Magnetic resonance Imaging
–MRA - Magnetic resonance
angiogram
–PET - Positron emission scan
–EEG - Electroencephalography
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Lumbar Puncture (LP)
 A needle
is inserted in the spinal cord for
removal of CSF.
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MRA and MRI
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MRI
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CT Scan
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PET scan reveals the cellular level metabolic
changes occurring in an organ or tissue.
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PET Scan - Positron Emission
Tomography
• The red color shows the highest level of
glucose utilization, yellow represents less
utilization and blue shows the least.
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Abbreviations page 429
• AD
Alzheimer disease
• ALS
amyotrophic lateral sclerosis
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Abbreviations – page 429
CNS
central nervous system
CT
computed tomography
CVA
cerebrovascular accident
CSF
cerebrospinal fluid
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Abbreviations
• EEG
Electroencephalogram
• ICP
intracranial pressure
• LP
lumbar puncture
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Abbreviations
• MG
myasthenia gravis
• MRA
magnetic resonance
angiography
• MRI
magnetic resonance
imaging
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Build Medical Terms
1.pertaining to the cerebrum and spine:
2.incision of the cranium (skull):
3.crushing a nerve:
4.hernia(tion) of meninges and spinal cord:
74
Build Medical Terms
1.pertaining to the cerebrum and spine:
cerebrospinal
2.incision of the cranium (skull): craniotomy
3.crushing a nerve: neurotripsy
4.hernia(tion) of meninges and spinal cord:
meningomyelocele
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Build Medical Terms
5.inflammation of gray matter of spinal
cord:
6.paralysis of four (limbs):
7.tumor of nerve, embryonic cell:
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Build Medical Terms
5.inflammation of gray matter of spinal
cord: poliomyelitis
6.paralysis of four (limbs): quadriplegia
7.tumor of nerve, embryonic cell:
neuroblastoma
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Build Medical Terms
8.pertaining to the cerebrum:
9. condition of water in the head:
10. separation, destruction, or loosening of
a nerve:
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Build Medical Terms
8.pertaining to the cerebrum: cerebral
9. condition of water in the head:
hydrocephalus
10. separation, destruction, or loosening of
a nerve: neurolysis
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Craniotomy
– Incision of the skull to gain access to
the brain during neurological
procedures.
– Performed to control brain bleeds,
relieve intracranial pressure (ICP),
and remove brain tumors.
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Pharmacology
•Anesthetics
• Produce partial or complete loss of
sensation, with or without loss of
consciousness.
• General anesthetics act on brain to produce complete
loss of consciousness.
• Local anesthetics act on nerves or nerve tracts to
affect a local area only.
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Pharmacology
•Anticonvulsants
– Prevent or reduce severity of epileptic or
other convulsive seizures; also called
antiepileptics.
•Antiparkinsonian agents
– Control tremors and muscle rigidity associated
with Parkinson disease by increasing
dopamine levels in the brain.
82
Pharmacology
•Antipsychotics
– Alter neurotransmitters in the brain to
alleviate symptoms of psychosis, paranoia,
and schizophrenia.
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