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The Divisions of the Nervous System

The Divisions of the Nervous System. The Nervous Syste m. General Function: Controls and coordinates all of the systems in the body. Divisions of the Nervous System. 1. Central Nervous System (CNS) The “thinker” or information processor. Consists of the brain and spinal cord.

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The Divisions of the Nervous System

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  1. The Divisions of the Nervous System

  2. The Nervous System • General Function: • Controlsand coordinates all of the systems in the body.

  3. Divisions of the Nervous System • 1. Central Nervous System (CNS) • The “thinker” or information processor. • Consists of the brain and spinal cord. • The brain processes and integrates information. • The spinal cord carries impulses to and from the brain and communicates between the brain and the peripheral nervous system.

  4. Divisions of the Nervous System • 2. Peripheral Nervous System (PNS) • The “doer” it carries out action. • Connects the CNS to muscles and glands. • Includes motor and sensory nerve pairs.

  5. The Peripheral Nervous System • The peripheral nervous system has two branches, the somatic nervous system and the autonomic nervous system.

  6. The Peripheral Nervous System • Somatic System: • Function • Controls all voluntary muscles (ie. Skeletal muscles) • Some reflex action originates here. • Movement (voluntary and reflex) originates here.

  7. The Peripheral Nervous System • Kinds of nerves: • Motor neurons: • Carry information from the CNS to the muscles and glands. • Sensory neurons: • Carry information about the environment to the CNS. • Contain ganglia.

  8. The Peripheral Nervous System • Autonomic Nervous System: • Function: • Controls all involuntary actions to control homeostasis. • Controls all internal organs (ie. Heart, lungs, liver, glands…) • This system has two divisions, the sympathetic and the parasympathetic.

  9. The Peripheral Nervous System • Sympathetic Division: • The accelerator – important during emergencies. • Fight or flight response. • Uses norepinephrine as main neurotransmitter. • Norepinephrine yields adrenaline (from the adrenal cortex)

  10. The Peripheral Nervous System • Adrenaline causes: • Increased heart rate • Bronchi dilate (more oxygen for muscles) • Skeletal muscles tense for battle • Pupils dilate • Digestion inhibited • Tears inhibited

  11. The Peripheral Nervous System • The nerves in the sympathetic division originate from the middle (thoracic and lumbar) of the spinal cord. • They contain many ganglia (swellings from cell bodies). • The preganglionic fibers are short while the post are long.

  12. The Peripheral Nervous System • Parasympathetic Division: • The “brakes” • Returns system to normal resting state. • Normal digestion, heart rates, etc… • Uses acetylcholine as main neurotransmitter. • Nerves originate from the top (cervical) and bottom (sacral) of the spinal cord.

  13. The Peripheral Nervous System • Parasympathetic nerves have long preganglionic fibers and short post.

  14. The Peripheral Nervous System • For example: • Liver: • Sympathetic fibers • Stimulate glycogen conversion to glucose for more ATP • Parasympathetic fibers • Stimulate liver to release bile for normal digestion

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