neuro – a & p, assessment, diagnostics chapter 41 spring news news
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Neuro – A & P, Assessment, DiagnosticsChapter 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
• 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
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
• 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
• 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– 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
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 SystemArea Affected Sympathetic Parasympathetic
Pupil Dilates Constricts
Bronchi Dilates Constricts
Heart Increases Rate Decreases Rate
GI Inhibits peristalsisStimulates sphincter
Stimulates peristalsisInhibits sphincter
Adrenal Glands Increases secretion of EN and NE
Bladder Relaxes Bladder muscleConstricts sphincter
Contracts bladder muscleRelaxes sphincter
Neurological Assessment
History• Family history/genetic risks• Personal history• Current health problems• Social history
Mental Assessment
• 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
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