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Nervous SystemUnit 2: Cells, Tissues & Organ Systems
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OverviewThe human brain contains about 100 billion
nerve cells or neurons
Each neuron may communicate with thousands of other neurons
All animals except sponges have a nervous system
What distinguishes nervous systems of different animal groups is how neurons are organized into circuits.
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The Nervous System
The central nervous system (CNS) consists of a brain and spinal cord
The peripheral nervous system (PNS) contains all the nerves to relay information from the environment to the brain. It also controls
involuntary body responses such as digestion and breathing.
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Nerve Tissue
Nerve tissue is made up of cells called neurons.
100 billion in the human brain
Conduct electrical signals (nerve impulses) from one area to another.
Insulated by myelin
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Information ProcessingNervous systems process information in three
stages: Sensory input Integration Motor output
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Sensory ReceptorsSpecial cells or tissues that receive input from
the external environment and send signals along the peripheral nervous system to the central nervous system.
Eyes, ears, mouth, muscles and skin have sensory receptors
Information goes to different parts of the brain.
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LE 48-3
Sensor
Sensory input
Motor output
Integration
EffectorPeripheral nervous
system (PNS)Central nervous
system (CNS)
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Different parts of the brain receive information from various senses
Cerebellum
Brainstem
Cerebrum
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ReflexesReflexes are actions that do
not need involvement of the brain. That is the brain is not involved in the decision to move.
Examples Knee jerk Moving hand away from a hot
stove
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Diseases of the Nervous SystemMultiple sclerosis
Huntington’s
Concussion
Epilepsy
Stroke
Parkinson’s
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Videos and Additional Information to Checkout for Homework!! http://www.youtube.com/watch?v=i-NgGKSNiN
w&feature=related
http://www.youtube.com/watch?v=xRkPNwqm0mM&feature=related (nervous system - 51 sec)
http://www.youtube.com/watch?v=QmNQdLkkJHM (on reflexes) (19 sec)
http://kidshealth.org/PageManager.jsp?lic=1&article_set=59295&cat_id=20607 (animation - ~ 3 min)
http://www.youtube.com/watch?v=fY7J7bccNoU (concussions – 20 sec)
http://www.youtube.com/watch?v=oY19-JI648Q (teenage with a concussion – 3 min)