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Autonomic Nervous System
- Peripheral Nervous System (PNS)
- Motor (efferent) Division
- Transmits from CNS to effectors
- Involuntary
- Innervates smooth muscle, cardiac muscle, glands
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Two Neuron Chain
Preganglionic neuron > Ganglionic neuron
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Preganglionic Neuron
- Cell body lies within the brainstem or spinal cord
- Extends from the cell body and exits the CNS in either a cranial nerve or spinal nerve
- Attaches to Ganglionic Neuron in PNS
- Presynaptic neuron
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Ganglionic Neuron
- post-synaptic neuron
- cell body in autonomic ganglia
- Take impulse from Preganlionic Neuron transmits to effector organ
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Divisions of the Autonomic Nervous System (ANS)
- Parasympathetic and Sympathetic divisions
- Both innervate same organs but with opposite effects (Antagonistic) Originate from different CNS regions
- Both have myelinated preganglionic axons and unmyelinated postganglionic axons
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Crainosacral division
parasympathetic division
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Thoracolumbar division
Origin of Sympathetic division
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Parasympathetic Divsion
- "Rest & Digest"
- Energy conservation
- Cell bodies in brainstem & S2-S4 lateral gray horns
- Axons exhibit little or no branching
- Long preganglionice axon
- Short postganglionic axon
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Sympathetic Division
- "Fight or Flight"
- More complex vs parasympathetic
- Cell bodies located in T1 & L2 lateral gray horns
- Both axons are more highly branched
- Short Preganglionic axon
- Long Postganglionic axon
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Ganglionic Neurons (Parasympathetic)
- Either found in terminal ganglia, which are located close to the target organ
- Or intramural ganglia, which are located within the wall of target organ
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Ganglionic neurons (Sympathetic)
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