Chap 21: ANS – Snow College Anatomy
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What part of the vertebrate nervous system innervates smooth and cardiac muscle and glandular tissues and governs involuntary, vital functions?
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The autonomic nervous system
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If we follow a nerve impulse from the CNS to an effector within the SNS, how many motor neurons would be involved?
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One
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If we follow a nerve impulse from the CNS to an effector within the ANS, how many motor neurons would be involved?
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Two
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A motor neuron within the ANS that lies between the CNS and a ganglion is what type of neuron?
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Preganglionic neuron
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A motor neuron within the ANS that lies between a ganglion and an effector is what type of neuron?
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Ganglionic neuron
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What is the axon of a ganglionic neuron within the ANS?
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Postganglionic axon
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What are the two divisions of the ANS?
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Parasympathetic Sympathetic
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What division of the ANS is primarily concerned with conserving energy and replenishing nutrient stores and has been nicknamed the "rest-and-digest" division?
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Parasympathetic
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What division of the ANS is primarily concerned with preparing the body for emergencies and is often referred to as the "fight-or-flight" division?
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Sympathetic
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What is another term for the parasympathetic division?
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Craniosacral division
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Where are the cell bodies of the preganglionic neurons for the parasympathetic division located?
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Brainstem Gray regions of S2-S4 spinal cord segments
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Where are the ganglia of the parasympathetic division found?
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Next to or within the organs they innervate
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What cranial nerves carry parasympathetic fibers?
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Oculomotor (CN III) Facial (CN VII) Glossopharyngeal (CN IX) Vagus (CN X)
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The parasympathetic division innervates what structures through the oculomotor nerve?
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Ciliary muscle Pupillary constrictor muscle of the iris
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The parasympathetic division innervates what structures through the facial nerve?
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Lacrimal gland Nasal mucosa Submandibular and sublingual salivary glands
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The parasympathetic division innervates what structures through the glossopharyngeal nerve?
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Parotid salivary gland
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The parasympathetic division innervates what structures through the vagus nerve?
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Airways Heart Abdominal viscera
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What specific regions of the spinal cord house the cell bodies of the parasympathetic division of the ANS?
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Lateral gray regions of the S2-S4 spinal cord segments
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What nerves carry fibers of the parasympathetic division of the ANS through the pelvis?
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Pelvic splanchnic nerves
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What does "splanchnic" mean?
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Visceral
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You miss lunch and only have time for a bag of chips. What division of the ANS brings about an increase in the production of saliva as you eat?
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Parasympathetic
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You walk from a relatively dim building into the brightness of a sunny winter's day. Your pupils constrict. What division of the ANS brings about this constriction?
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Parasympathetic
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A test in the Testing Center takes longer than you anticipated. Now you're late for your next class. You jog. You arrive and settle into your seat. The airways in your lungs constrict was you catch your breath. What division of the ANS brings about this constriction?
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Parasympathetic
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A bit of dirt gets blown into your eye. Tears flow. What division of the ANS brings about the flow?
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Parasympathetic
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What is another term for the sympathetic division of the ANS?
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Thoracolumbar division
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From what regions of the CNS does the sympathetic division arise?
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The lateral horns of the T1-L2 regions of the spinal cord
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What part of spinal nerves do the preganglionic sympathetic axons travel within as they leave the lateral horn of the spinal cord?
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Anterior root
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What sympathetic ganglia lie on the left and right sides of the vertebral column from T1-L2?
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Sympathetic trunk (paravertebral or chain) ganglia
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What structure the sympathetic division of the ANS has the appearance of a pearl necklace?
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Sympathetic trunk (paravertebral or chain) ganglia
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What clusters of ganglia of the sympathetic division of the ANS lie within the neck?
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Cervical ganglia
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What are the connections between the spinal nerves and the sympathetic trunks?
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Rami communicates (communicating rami)
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What structures carry preganglionic sympathetic axons from the T1-L2 spinal nerves to the sympathetic trunk?
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White rami communicantes (white rami)
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What structures carry postganglionic sympathetic axons from the sympathetic trunk to the spinal nerves?
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Gray rami communicates (gray rami)
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What structures are composed of preganglionic axons that do not synapse in a sympathetic trunk ganglion?
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Splanchnic nerves
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Splanchnic nerves of the sympathetic division of the ANS terminate in what structures?
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Prevertebral (collateral) ganglia
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What structures are singular rather than paired, are anterior to the vertebral column, and are located only in the abdominal cavity?
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Prevertebral ganglia
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List the three prevertebral ganglia.
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Celiac ganglion Superior mesenteric ganglion Inferior mesenteric ganglion
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What pathway is a postganglionic axon within if it travels through a gray ramus that is at the same level as the ganglionic neuron to innervate blood vessels or arrector pili muscles or sweat glands?
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Spinal nerve pathway
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What pathway is a postganglionic axon within if the preganglionic neuron synapses with a ganglionic neuron in a sympathetic trunk ganglion, but the postganglionic axon does not leave the trunk via a gray ramus, but instead the postganglionic axon extends away from the sympathetic trunk ganglion and goes directly to the effector organ?
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Postganglionic sympathetic nerve pathway
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What pathway is postganglionic axon within if it passes through the sympathetic trunk ganglia without synapsing and extends to the prevertebral ganglia?
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Splanchnic nerve pathway
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What pathway is a sympathetic axon within if it goes to the adrenal medulla?
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Adrenal medulla pathway (aka sympathoadrenal pathway)
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The pupil dilates when a person walks into a relatively dark building from a bright, snowy winter's day. What division of the ANS brings about this dilation?
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Sympathetic division
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A test in the Testing Center takes longer than you anticipated. You're late for your next class. You jog. As you do the airways in your lungs dilate. What division of the ANS brings about this dilation?
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Sympathetic division
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After class you go for a game of racquetball and work up a sweat. What division of the ANS causes the formation of sweat?
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Sympathetic
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If you are driving a Sanpete County road on winter's day and a deer suddenly takes a suicidal leap in front of your car, what is the general response of your ANS?
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Fight-or-flight
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Usually both divisions of the ANS innervate organs. Where does this dual innervation not occur?
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In the skin and skeletal muscles -There is only sympathetic innervation here.
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What are collections of sympathetic postganlionic axons and parasympathetic preganglionic axons, as well as some visceral sensory axons?
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Autonomic plexuses
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List the five autonomic plexuses.
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Cardiac plexus Pulmonary plexus Esophageal plexus Abdominal aortic plexus Hypogastric plexus
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What part of the CNS has the greatest control over the ANS?
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Hypothalamus
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What part of the CNS holds nuclei which have a great deal of influence over autonomic function?
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Brainstem
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What division of the ANS may process and control certain functions at the level of the spinal cord without involvement of the brain?
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Parasympathetic
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What cranial nerve carries nearly 80% of the parasympathetic output?
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Vagus
