The autonomic nervous system
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Created by:
phisigmaria on December 16, 2011
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15 terms
Terms | Definitions |
|---|---|
 ANS | The system of motor neurons that innervates smooth and cardiac muscles and glands. |
| 3 differences b/w ANS and PNS | effectors, efferent pathways, target organ responses to neurotransmitter. |
| type of ANS pathway? | two neuron chain to its effector |
| preganglionic neuron | cell body of first neuron that resides in brain or spinal cord |
| preganglionic axon | axon of preganglionic neuron, synapses with 2nd motor neuron, ganglionic neuron. lightly myelinated thin fibers. |
| ganglionic neuron | second motor neuron resides in autonomic ganglion outside CNS. |
| postganglionic axon | axon of the ganglionic neuron, it extends to the effector organ. Even thinner axon and unmyelinated. |
| autonomic ganglia | collections of nerve cell bodies, belonging to the autonomic division of the peripheral nervous system, sites of synapse and information transmission from preganglionic to ganglionic neurons. |
| norepinephrine | neurotransmitter released onto visceral organs by postganglionic autonomic fibers secreted by sympathetic fibers. |
| ACh | neurotransmitter released by parasympathetic fibers. |
| effects of ANS neurotransmitters | either excitation or inhibition. |
| divions of ANS | sympathetic and parasympathetic division |
| sympathetic division | a branch of the autonomic nervous system and prepares the body for quick action in emergencies; fight or flight; busiest when frightened, angry, or aroused; increases heart rate, increases breathing rate, enlarges pupils, stops digestion; connects to all internal organs; sudden reaction (E division: exercise, excitement, emergency, embarrassment) |
| parasympathetic division | the part of the autonomic nervous system that monitors the routine operations of the internal organs (ex. elimination of feces and urine.) and returns the body to calmer functioning after arousal by the sympathetic division. "resting & digesting" (D division: digestion, defecation, diuresis) |
| Anatomical differences b/w sympathetic and parasympathetic divisions | 1-origin sites: parasympathetic fibers emerge from brain and sacral spinal cord, sympathetic originate in thoracolumbar region. 2-relative length of fibers: Parasympathetic long preganglionic and short postganglionic fibers, sympathetic have opposite. 3-location of their ganglia: parasympathetic located in visceral organs, sympathetic located close to spinal cord. |
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