Central Nervous System

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Central Nervous System

• Chapter 9
• READ CHAPTER

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Central Nervous System

• Cerebral ganglia (brain)
• Spinal Cord

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6 Major Regions of the Brain

• 1.) Cerebrum
• 2.) Diencephalon
• 3.) Cerebellum
• 4.) Midbrain
• 5.) Pons
• 6.) Medulla Oblongata

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Cerebrum
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Cerebrum

• Cerebral Gray Matter
• Interior of cerebrum contains 3 clusters of cell
  bodies
• 1.) Cerebral Cortex
• 2.) Basal ganglia corpus striatum
• Control of movement
• 3.) Limbic System

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Cerebral Cortex

• Neurons of the cortex are arranged in
  anatomically distinct horizontal layers, and
  functionally distinct vertical columns
• Higher brain functionreasoning

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(Parietal)
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Limbic System

• Region of the cerebrum that surrounds the brain
  stem
• Link between higher cognitive functions such as
  reasoning and emotions
• Major areas of Limbic System
• 1.) amygdalalinked to emotion and memory
• 2.) cingulate gyruslinked to emotion
• 3.) hippocampuslearning and memory

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Limbic System

• Also includes centers within the hypothalamus
  responsible for
• 1.) emotional statesrage, fear, and sexual
  arousal
• 2.) control of reflexes that can be consciously
  activated like chewing, licking, and swallowing

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Figure 9-13
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Cerebral Lateralization

• Language/Verbal left
• Dominant for Right handed people
• Spatial Skills Right

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External Support For Nervous Tissue

• BONE Casing
• Skull or cranium brain
• Vertebral column spinal cord

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External Support for Nervous Tissue

• Cerebrospinal Fluid (CSF)
• Salty solution continuously secreted into
  ventricles (hollow cavities) of the brain

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Choroid Plexus

• Choroid plexus specialized tissue found on the
  walls of the ventricles
• Secretes CSF
• Consists of capillaries and transporting
  epithelium Ependyma
• Ependyma actively pump Na and other solutes
  into the ventricles, creating an osmotic gradient
  that draws water into the ventricles

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CSF

• 1.) Physical protection
• 2.) Regulate extracellular fluid environment
• Concentrations of K, Ca, HCO3-, and glucose are
  lower, and H is higher in CSF as compared to
  plasma
• CSF contains very little protein, and no blood
  cells

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Blood-Brain Barrier

• Capillaries in the brain are much less permeable
  than most capillaries of the body
• Endothelial cells connect through tight junctions
• Tight junction formation induced by paracrine
  release from adjacent astrocytes

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Spinal Cord

• Major Pathway of information between brain and
  the skin, joints, and muscles
• Network for locomotion

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Spinal Cord

• 4 Regions
• Cervical
• Thoracic
• Lumbar
• Sacral

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Figure 9-4b (2 of 2)
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Spinal Cord

• Roots Just before a spinal nerve joins the
  spinal cord, it divides into 2 branches
• Dorsal root incoming sensory (afferent)
• Dorsal root ganglia cell bodies of sensory
  neurons

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Spinal Cord

• Ventral Roots information from CNS to muscles
  and glands efferent

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Spinal cord

• Interneurons of dorsal horn synapse with fibers
  from the dorsal roots
• Interneurons of the ventral horn synapse with
  fibers from the ventral roots

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Spinal Cord

• Ascending tracts sensory information to the
  brain dorsal and extra-lateral portions
• Descending tracts ventral and interior lateral

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Figure 9-7 - Overview
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Figure 9-8
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REVIEW of CHAPTER 9

• End of Chapter review questions
• Review Questions on the Web

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Chapter 10

• Sensory Neurobiology
• Pain Perception
• pp. 327-343

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Figure 10-1 - Overview
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Table 10-1
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Table 10-2
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Figure 10-2
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Intensity and Duration

• Cannot be directly calculated from a single
  sensory neuron action potentialall or none
  response
• 1.) Number of receptors
• 2.) Frequency of stimulus

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If stimulus persistssome receptors adaptcease
to respond

• 1. Tonic receptors Slowly adapting receptors
  that fire rapidly when first activated, then slow
  and maintain firing as long as stimulus is
  present
• Example Baroreceptors, irritant receptors,
  tactile receptors, proprioceptors

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• 2.) Phasic receptors rapidly adapting
  receptors that fire when the first receive
  stimulus, but cease firing if the strength of the
  stimulus remains constant
• Phasic receptors respond to a CHANGE in
  parametersonce a stimulus reaches steady state,
  phasic receptors turn off
• Example Olfactory receptors

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Somatic Senses
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Figure 10-9 - Overview
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Figure 10-11
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Table 10-4
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Nociceptors

• Receptors that respond to a variety of strong,
  noxious stimuli (chemical, mechanical, or therma)
  that cause or have the potential to cause tissue
  damage
• Sensory input initiates adaptive, protective
  responses, such as a reflexive action

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Nociceptor Pathways

• 1.) reflexive protective responses that are
  integrated at the level of the spinal cord
• 2.) ascending pathways to the cerebral cortex
  that become conscious sensation (pain or itch)

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Table 10-5
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Figure 10-12 - Overview
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Pain Management

• 1.) Aspirininhibits prostaglandins and slows
  transmission of pain signals from the site of
  injury
• 2.) opiates (morphine)-act directly on CNS opioid
  receptors to block pain perception