1. Nervous System Assistant prof. Dr. Omar College of Dentistry 2017-2018

2. Components of the Nervous System
Figure 11.1

3. Principle Parts of Nervous System
Central Nervous System (CNS)
Components: brain and spinal cord
Functions: receives, processes, and transfers information
Peripheral Nervous System (PNS)
Components: nerves outside CNS
Sensory neurons: carry information toward the CNS
Motor neurons: carry information away from CNS

4. Types of Neurons in the Nervous System
Sensory Neuron
Interneuron
Motor Neuron
Figure 11.2

5. Communication Cells of System
Neurons: Actual Communication Cells
Cell Body
Axon (one – away)
Dendrites (grow more with learning!)
Neuroglia: Support Cells of the Nervous System
Schwann Cells (PNS)
Oligoddendrocyte (CNS)

6. Myelinated Neuron
Figure 11.3

7. Myelin Sheath on Neuron
Myelin sheath: Schwann cells in PNS
Functions:
Saves the neuron energy
Speeds up the transmission of impulses
Helps damaged or severed axons regenerate
Myelin in CNS: formed by oligodendrocytes
In multiple sclerosis the sheaths of myelinated neurons of the CNS become scarred.

8. Neuroglia of the CNS Oligodendrocytes(CNS)
Produce myelin sheath around nerve fibers in the central nervous system
Figure 7.3d
Slide 7.7a
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9. Support Cells of the PNS
Schwann cells
Form myelin sheath in the peripheral nervous system
Figure 7.3e
Slide 7.7b
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10. Neuroglia vs. Neurons Neuroglia divide. Neurons do not.
Most brain tumors are “gliomas.”
Most brain tumors involve the neuroglia cells, not the neurons.
Consider the role of cell division in cancer!

11. How Neurons Function (Physiology)
Irritability – ability to respond to stimuli
Conductivity – ability to transmit an impulse
The plasma membrane at rest is polarized
Fewer positive ions are inside the cell than outside the cell
Slide 7.17
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12. Continuation of the Nerve Impulse between Neurons
Impulses are able to cross the synapse to another nerve
Neurotransmitter is released from a nerve’s axon terminal
The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter
An action potential is started in the dendrite
Slide 7.21
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13. How Neurons Communicate at Synapses
Figure 7.10
Slide 7.22
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14. Transfer of Information from Neuron to Target
Synaptic transmission
Release of neurotransmitter
Effects of neurotransmitter:
Electrical energy converted to chemical energy
cell
Role of postsynaptic neuron: integrate and process information
Role of postsynaptic muscle cell – must respond.
Nervous system has final and absolute control over skeletal muscle cells!

15. Peripheral Nervous System: Relay Information between Tissues and CNS
Nerves: carry signals to and from CNS
Cranial nerves: connect directly to brain
Spinal nerves: connect to spinal cord
Sensory neurons: provide information to CNS

17. Motor or Output Neurons are Organized into Somatic and Autonomic Divisions
Voluntary and Involuntary Skeletal Muscle Movement
Includes Reflex arcs.
Autonomic
Carry information to smooth or cardiac muscle
Automatic
Two types: Sympathetic and Parasympathetic

18. Simple Reflex Arc Slide 7.24 Figure 7.11b, c
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19. Autonomic Functioning
Sympathetic – “fight-or-flight”
Response to unusual stimulus
Takes over to increase activities
Remember as the “E” division = exercise, excitement, emergency, and embarrassment
Slide 7.74a
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20. Autonomic Functioning
Parasympathetic – housekeeping activites
Conserves energy
Maintains daily necessary body functions
Remember as the “D” division - digestion, defecation, and diuresis
Slide 7.74b
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21. Anatomy of the Autonomic Nervous System
Figure 7.25
Slide 7.73
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22. Comparison of Somatic and Autonomic Nervous Systems
Figure 7.24
Slide 7.69
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23. Central Nervous System: Brain & Spinal Cord
CNS protection
Bone: skull and vertebrae
Meninges: dura mater, arachnoid, and pia mater
Cerebrospinal fluid: between arachnoid and pia
Blood-brain barrier: carries nutrients and waste for CNS
Spinal cord: relays information through nerve tracts in white matter

24. Ventricles of the Brain and Circulation of Cerebrospinal Fluid
Figure 11.12

25. Protection of the Central Nervous System
Scalp and skin
Skull and vertebral column
Meninges
Figure 7.16a
Slide 7.44a
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26. Brain: Major Divisions
Hindbrain: coordinates basic, automatic, vital functions
Medulla oblongata: controls automatic functions of internal organs
Cerebellum: coordinates basic movements
Pons: aids flow of information
Midbrain: coordinates muscles related to vision & hearing
Reticular Formation - Wakefulness

27. Brain: Processes and Acts on Information
Forebrain: receives and integrates information concerning emotions and conscious thought
Hypothalamus: helps regulate homeostasis
Thalamus: receiving, processing, and transfer center
Limbic system: neuronal pathways involved in emotions and memory
Cerebrum/cerebral cortex: higher functions

28. Regions of the Brain Cerebral hemispheres Diencephalon Brain stem
Cerebellum
Figure 7.12
Slide 7.27
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29. Cerebral Hemispheres (Cerebrum)
Paired (left and right) superior parts of the brain
Include more than half of the brain mass
Figure 7.13a
Slide 7.28a
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30. Cerebral Hemispheres (Cerebrum)
The surface is made of ridges (gyri) and grooves (sulci)
Figure 7.13a
Slide 7.28b
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31. Lobes of the Cerebrum
Fissures (deep grooves) divide the cerebrum into lobes
Surface lobes of the cerebrum
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
Slide 7.29a
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32. Lobes of the Cerebrum Slide 7.29b Figure 7.15a
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33. Specialized Areas of the Cerebrum
Somatic sensory area – receives impulses from the body’s sensory receptors
Primary motor area – sends impulses to skeletal muscles
Broca’s area – involved in our ability to speak
Slide 7.30
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35. Specialized Area of the Cerebrum
Figure 7.13c
Slide 7.32c
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36. Sensory and Motor Areas of the Cerebral Cortex
Figure 7.14
Slide 7.31
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37. Thalamus -Surrounds the third ventricle
-The relay station for sensory impulses
-Transfers impulses to the correct part of the cortex for localization and interpretation
Slide 7.35
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38. Hypothalamus Under the thalamus
Important autonomic nervous system center
Helps regulate body temperature
Controls water balance
Regulates metabolism
Slide 7.36a
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39. Hypothalamus An important part of the limbic system (emotions)
The pituitary gland is attached to the hypothalamus
Slide 7.36b
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40. Hind Brain: Pons The bulging center part of the brain stem
Mostly composed of fiber tracts
Includes nuclei involved in the control of breathing
Slide 7.40
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41. Medulla Oblongata The lowest part of the brain stem
Merges into the spinal cord
Includes important fiber tracts
Contains important control centers
Heart rate control
Blood pressure regulation
Breathing
Swallowing
Vomiting
Slide 7.41
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42. Cerebellum Two hemispheres with convoluted surfaces
Provides involuntary coordination of body movements
Slide 7.43a
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43. Cerebellum Slide 7.43b Figure 7.15a
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46. Brain Activity continues during sleep!
Sleep: Midbrain
Brain Activity continues during sleep!
Sleep center: reticular activating system (RAS)
Stages: based on electroencephalograms (EEGs)
Stage 1: transitional, random small waves on EEG
Stage 2: skeletal muscles relax, little eye or body movement, EEG shows sleep spindles

47. Sleep Stage 3: heart and respiration slower, EEG shows slow wave sleep
Stage 4: difficult to awaken, heart and respiration slowest, body temperature decreased
REM (rapid eye movement) Sleep: dreaming, EEG same as awake. Lack of REM = sleep deprivation
Sleep cycles through these stages, REM occurring every 90 minutes of so.

48. Memory: Storing and Retrieving Information
Short term: working memory, information from previous few hours
Occurs in the Limbic System
Long term: information from previous days to years
Occurs in the Cerebral Cortex
Permanent Change to Neurons
“Builoding Dendrites

49. Alzheimer’s Disease Progressive degenerative brain disease
Mostly seen in the elderly, but may begin in middle age
Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons
Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death
Slide 7.51
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50. Traumatic Brain Injuries
Concussion
Slight brain injury
No permanent brain damage
Contusion
Nervous tissue destruction occurs
Nervous tissue does not regenerate
Cerebral edema
Swelling from the inflammatory response
May compress and kill brain tissue
Slide 7.49
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51. Cerebrovascular Accident (CVA)
Commonly called a stroke
The result of a ruptured blood vessel supplying a region of the brain
Brain tissue supplied with oxygen from that blood source dies
Loss of some functions or death may result
Slide 7.50
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52. CNS DEFINITIONS Nucleus-collection of nerve cells inside the CNS
Ganglion-collection of nerve cell bodies outside the CNS
Centers- collections of cell bodies and dendrites in the CNS
Tracts-bundles of axons within the CNS