Download Chapter 45 Central Nervous System BRain

Neuro – A & P, Assessment, Diagnostics
Chapter 41
Spring
News
Grey’s Anatomy Quote
• The brain is the human body's most
mysterious organ. It learns. It changes. It
adapts. It tells us what we see. What we
hear. It lets us feel love. I think it holds
our soul. But no matter how much
research we do, no one can really say
how all that delicate gray matter inside
our skull works. And when it's hurt, when
the human brain is traumatized, well...
that's when it gets even more mysterious.
Nervous System
• What does it do?
• How does it do it?
ANATOMY
Neurons
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Initiate and transmit impulses
High metabolic rate
Longevity
Typically non-mitotic
Variety of shapes and sizes
Comprised of a cell body, dendrites and
axons
Sensory vs. Motor
• Sensory Neurons (afferent)
– Transmit information to the CNS
• Motor Neurons (efferent)
– Transmit information away from the CNS
Impulse Conduction
Reflex Arc
– Functional unit that provides the pathways for
the nerve impulses
– The passage of the impulses is called
• Reflex act or Reflex
– Process of Reflex Arc
• Neural impulses
Anatomy
Neuroglial Cells
– Four types
• Capable of mitosis and replacing
damaged neurons
• Aid in neuronal development
• Do not transmit nerve impulses
• Protect, nourish and provide support for
the neurons
Anatomy
Action Potentials
– Movement of an electrical charge thru an
impulse along the axon membrane
– Allows for communication with neurons and
body cells
– Initiated by a stimulus
– Propagated by rapidly charged ions thru the
cell membrane
– Faster in myelinated fibers
Anatomy
Neurotransmitters
• Synaptic Transmission
– One way communication that link the
neurons by a chemical synapse
– Either inhibitory or excitatory
– Chemical neurotransmitters
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Acetylcholine
Norepinephrine
Dopamine
Histamine
GABA (gamma aminobutyric acid)
Serotonin
Factors Effecting
Neurotransmission
• Distance
• Strength of Stimulus
– Inhibition
– Inadequate transmitter substance
– ECF changes
• pH
• O2
• Medications
PHYSIOLOGY
Physiology
• Central Nervous System (CNS)
– Brain
– Spinal Cord
Brain Parts and Function
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Bone
Meninges
Cerebrum
Brainstem
Circle of Willis
Brain
Table 41-1 General
Functions of the Four
Regions of the Brain
Figure 41–3 Lobes of the
cerebrum and functional areas of
the cerebral cortex.
Table Functions of Lobes of
the Cerebrum and Areas of
the Cerebral Cortex
CSF
• Clear and Colorless
• From blood plasma – 99% water
– Contains protein, sodium, chloride,
potassium, bicarbonate and glucose
• 80 – 200 mL total volume
– Replaced several times per day
• Cushion for the brain and spinal column
• Provides nourishment and removes
waste
Circulation and the BBB
Circulation
• 750 mL of blood per minute
• Uses 20% of the total O2
– Needed for the metabolism of glucose – sole
source of energy.
BBB
• Allows lipids, glucose, some amino acids,
water, CO2 and O2
• Other substances are prevented from
crossing
Figure 41–5 Major arteries
serving the brain and the Circle of
Willis.
Spinal Cord
• Center for conducting messages to and
from the brain and a reflex center
• 33 vertebrae
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7 cervical
12 thoracic
5 lumbar
5 sacral
4 fused which form the coccyx
Function
Ascending tracts- start in spinal cord and
end in the brain
• Spinothalamic
• Spinocerebellar
Descending tracts - start in the brain and
end in the spinal cord
Physiology
• Peripheral Nervous System (PNS)
– 12 pairs of Cranial nerves
– 31 pairs of Spinal nerves
– Autonomic nervous system
• Sympathetic system
• Parasympathetic system
• Cranial Nerve Song
Dermatones
• Area of skin that is innervated by
cutaneous branches of a single spinal
nerve
• Provide anatomic landmarks to locate
neurologic lesions
Autonomic Nervous System
Regulates involuntary activity
(cardiovascular, respiratory, metabolic,
body temps etc)
• Sympathetic (SNS)
• Parasympathetic (PNS)
Autonomic Nervous System
Area Affected
Sympathetic
Parasympathetic
Pupil
Dilates
Constricts
Bronchi
Dilates
Constricts
Heart
Increases Rate
Decreases Rate
GI
Inhibits peristalsis
Stimulates sphincter
Stimulates peristalsis
Inhibits sphincter
Adrenal Glands
Increases secretion of EN
and NE
Bladder
Relaxes Bladder muscle
Constricts sphincter
Contracts bladder muscle
Relaxes sphincter
Neurological Assessment
History
• Family history/genetic risks
• Personal history
• Current health problems
• Social history
Mental Assessment
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Mental status
Memory
Attention
Language/Copying
Cognition
Cranial Nerve Assessment
• Done to establish a baseline for
future comparison to rule out
deterioration
Sensory Function
Assessment
• Completed on patients with
problems affecting spinal cord or
spinal nerves: trauma,
intervertebral disk disease,
infections
• Evaluate: pain, temperature
touch
Figure 41–12 Testing two-point
discrimination.
Assessment of Motor
Function
• Muscle strength
• Cerebral/brainstem integrity
• Pronator Drift
Assessment of Cerebellar
Function
• Coordination
• Gait and equilibrium
Figure 41–13 Heel-to-shin test.
Assessment of Reflex
Activity
• Deep tendon reflexes
• Cutaneous (Superfical) reflexes
• Abnormal findings
Box 41-1 Abbreviated Neurologic
Assessment (Neuro Check)
Table 41-5 Glasgow Coma Scale
Diagnostic Assessment
• Laboratory
–CSF
• Lumbar Puncture
Diagnostic Assessment
• Radiographic
–Cerebral Angiography
–CT
–PET
–SPECT
–Cerebral Blood Flow Evaluation
–Brain Scan
Diagnostic Assessment
• Other
–MRI
–EEG
–EMG
–Transcranial Doppler