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THE NERVOUS SYSTEMExploring a Few Chords
Ruth DuBois, BScN, MA
2018
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FUNCTIONS OF THE NERVOUS SYSTEM
u Senses changes inside and outside body
u Integrates incoming information
u Effects responses (i.e. muscles and glands)
u Works with the endocrine system
u Highly complex, rapid electrical impulses
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CENTRAL NERVOUS SYSTEM
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PERIPHERAL NERVOUS SYSTEM
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AUTONOMIC NERVOUS SYSTEMSYMPATHETIC
ü “FIGHT OR FLIGHT”
ü Increased heart & blood pressure
ü Dilation of respiratory passages
ü Stimulates epinephrine release
ü Sweat glands stimulated
ü Dilated pupils
ü Liver releases glucose (from glycogen)
ü Inhibition of digestion, urination, and defecation (sphincters tighten)
ü Causes ejaculation of semen
PARASYMPATHETIC
ü “MAINTENANCE, HOUSEKEEPING”
ü Stimulates digestive, urinary functions
ü Slows heart rate
ü Constricts respiratory passages
ü Constricts pupil, bulges lens of eye for close vision
ü Causes erection of the penis
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SUPPORTING CELLS
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NEURON§ Over 100 billion neurons in the brain and spinal cord; represents over 965 km. in length
§ Excitable: Receives stimuli and transmits impulses by electrical and chemical means, up to 100 meters/second
§ Neurons transmit sensory information towards the CNS, and motor information away from the CNS to effectors (muscle, gland)
§ Transmission: unidirectional, all-or-none action potentials
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The SYNAPSE
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NEUROTRANSMITTERS
u Neurotransmitters act to carry a message from the axonal end of a neuron across the synapse to another neuron, muscle cell, or gland
u Response of the post-synaptic cell is either stimulation or inhibition of post-synaptic transmission of impulse
EXAMPLES:
u Norepinephrine (adrenaline)
u Acetylcholine
u Dopamine
u Serotonin
u GABA (gamma-aminobutyric acid)
u Endorphins
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u https://www.youtube.com/watch?v=GIGqp6_PG6k
Dance of the Neurons
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‘NEW’ UNDERSTANDING OF THE BRAIN
u NEUROPLASTICITY vs. a locationist view of the brain
u ‘The ability of the brain to form and reorganize synaptic connections, especially in response to learning or experience or following injury’
u Lifelong capacity though plasticity is most highly reflected during early development of the brain
u Debate surrounds whether new neurons can be ‘born’ and integrated into the hippocampus of human brains after infancy
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Brain Mapping
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THE BRAIN
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THE BRAIN
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REFLEX ARCS
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Normal Aging of the Nervous System
u Gradual decrease in sensory neurons
u Decreased position sense affecting balance and coordination
u Reduced sensations of thirst, objects in the throat, urine in the bladder, and feces in the rectum
u General gradual decline in # motor neurons, leads to reduced muscle mass (age 60+)
u Slowed reflexes
u Slight decrease in short term memory after age 70+
u Long term memory may even improve
u Sleep changesThis Photo by Unknown Author is licensed under CC BY-SA
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PAIN
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Perception of Acute Pain—A Warning
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Gate Control Theory Melzack & Wall
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COMPARISON: ACUTE AND CHRONIC PAIN
u Purposeful, warning sign of danger
u Associated with muscle spasm and sympathetic nervous system response
u Usually a NORMAL response to inflammation, tissue injury, disease process
u Self-limited until healing, or resolution of the disease
u If treated effectively, pain goes away in days or weeks as healing proceeds
u No biologic purpose
u Disease of ‘pain’
u May result from inadequate relief of acute pain, influenced by physical and psychological factors
u No end-point
u Elicits on-going stress response
u Treatment must be multi-modal, involving multi-disciplinary team
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Acute and Chronic Pain Presentations
Face of a Person in Acute Pain
Face of a Person With Chronic Pain
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Understanding Pain as a Disease
u https://www.ted.com/talks/elliot_krane_the_mystery_of_chronic_pain/discussion?ga_source=embed&ga_medium=embed&ga_campaign=embedT
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What importance might the information provided by Dr. Elliot
Krane have for you?
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LEARNING IN ALMONTE: THE NERVOUS SYSTEM
RECOMMENDED READING/VIEWING
BOOKS YOU MIGHT REALLY LIKE
u Doidge, N. (2007). The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science
u Doidge,N. (2016). The Brain’s Way of Healing: Remarkable Discoveries and Recoveries from the Frontiers of Neuroplasticity
Internet Programs
u https://ed.ted.com/lessons/the-mystery-of-chronic-pain-elliot-krane
u http://www.cbc.ca/natureofthings/episodes/the-brains-way-of-healing