Textbook Question
What two distinctive results are produced by the stimulation of sympathetic ganglionic neurons?
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14. The Autonomic Nervous System
Introduction to the Autonomic Nervous System
Problem 22
Textbook Question
Why does sympathetic function remain intact even when the anterior roots of the cervical spinal nerves are damaged?
Verified step by step guidance1
Understand the role of the sympathetic nervous system: The sympathetic nervous system is part of the autonomic nervous system, responsible for the 'fight or flight' response. It controls functions such as heart rate, blood pressure, and pupil dilation.
Identify the anatomical pathway of sympathetic fibers: Sympathetic fibers originate from the thoracolumbar region of the spinal cord (T1-L2), not the cervical spinal nerves. These fibers travel through the sympathetic chain ganglia, which are located adjacent to the vertebral column.
Recognize the role of the sympathetic chain ganglia: The sympathetic chain ganglia allow sympathetic signals to be distributed throughout the body, including the cervical region, even if the anterior roots of the cervical spinal nerves are damaged.
Clarify the independence of sympathetic function from cervical spinal nerves: Sympathetic function in the cervical region is maintained because the sympathetic fibers bypass the cervical spinal nerves and instead travel through the sympathetic chain ganglia.
Conclude the explanation: Damage to the anterior roots of the cervical spinal nerves does not affect sympathetic function because the sympathetic fibers originate from the thoracolumbar region and use the sympathetic chain ganglia to reach their target organs.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Sympathetic Nervous System
The sympathetic nervous system is a part of the autonomic nervous system responsible for the body's 'fight or flight' response. It originates from the thoracolumbar region of the spinal cord and controls involuntary functions such as heart rate, blood pressure, and digestion. Understanding its pathways is crucial for comprehending why sympathetic functions can persist despite damage to cervical spinal nerves.
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Spinal Nerve Anatomy
Spinal nerves are composed of anterior (ventral) and posterior (dorsal) roots, which carry motor and sensory information, respectively. The anterior roots are primarily responsible for motor functions, while the sympathetic fibers can travel through different pathways. Damage to cervical anterior roots may not affect sympathetic pathways that originate from other spinal levels, particularly those in the thoracic region.
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Autonomic Pathways
Autonomic pathways include both sympathetic and parasympathetic systems, which can operate independently. The sympathetic system has a complex network of ganglia and fibers that can bypass damaged areas. This redundancy allows sympathetic functions to remain intact even when specific spinal roots are compromised, highlighting the resilience of autonomic control in the body.
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