30 Questions
Which division of the nervous system is responsible for motor innervation of organs and glands?
Parasympathetic division
What type of response is associated with sympathetic activity?
Increase in heart rate
In the autonomic nervous system, what does the parasympathetic activity result in?
Increase in intestinal peristalsis & glandular activities
Where is the cell body of the postganglionic neuron in the sympathetic division located?
In the ganglion in the PNS
What type of transmission occurs at the synapse between preganglionic and postganglionic neurons in the sympathetic division?
Acetylcholine (ACh) to norepinephrine (NE)
What is the origin site of synapse for parasympathetic outflow?
Pelvic splanchnic nerves
Where are 75% of all parasympathetic fibers located?
Vagus nerve
What type of receptor does acetylcholine act on in the parasympathetic division?
Muscarinic receptor
9
Cranial nerves III, VII, IX, X have a parasympathetic component
What is the function of sympathetic activity?
Increase in heart rate & blood pressure
Which part of the nervous system directly connects to organs without synapsing at ganglia?
Prevertebral ganglia
Which region of the spinal cord contains parasympathetic neurons for the PNS?
T1L3(2) region
Which nerves provide parasympathetic input to most thoracic and abdominal viscera?
Vagus nerve
Which part of the nervous system is responsible for regulating peristalsis, gastrointestinal secretions, and gastrointestinal blood flow?
Vagus nerve
Which part of the SNS surrounds arteries?
Cervical sympathetic ganglia
Which sympathetic ganglia include the greater, lesser, and least splanchnic nerves?
Thoracic sympathetic ganglia
Which part of the nervous system has neurons located at the intermedio-lateral cell column of the spinal cord?
Parasympathetic nervous system (PNS)
Which nerves are innervated by sympathetic fibers without synapsing at paravertebral ganglia?
Prevertebral ganglia
Which part of the nervous system has independent fibers that directly connect to organs without synapsing at ganglia?
Prevertebral ganglia
Which part of the nervous system has four nuclei in the medulla oblongata and two sensory ganglia?
Vagus nerve
Which cranial nerve is responsible for innervating the parotid gland?
Glossopharyngeal nerve (Cranial Nerve IX)
Which ganglia contain the cell bodies of preganglionic neurons in the sympathetic division?
Paravertebral ganglia
Which nerve is responsible for regulating the viscera of the neck, thorax, foregut, midgut, and gastrointestinal tract?
Vagus nerve (Cranial Nerve X)
What is the primary pathway for sympathetic outflow?
Sympathetic trunk
Which clinical syndrome is caused by damage to the superior cervical sympathetic ganglion or its fibers?
Horner's syndrome
Where do preganglionic sympathetic fibers originate from?
Spinal cord
Which fibers leave the sympathetic trunk via gray rami communicantes?
Postganglionic fibers
Where do postganglionic fibers from the superior cervical ganglion innervate?
Dilator pupillae, smooth muscle of arteries, and head sweat glands
What is an exception to the general pattern of sympathetic outflow?
Adrenal medulla
What type of transmission occurs at the synapse between preganglionic and postganglionic neurons in the sympathetic division?
Cholinergic transmission
Study Notes
- Constrictor pupillae of the iris and the cilliary muscles are controlled by the parasympathetic system, while the sympathetic system regulates the dilation of the pupil.
- The facial nerve (Cranial Nerve VII) is responsible for the function of the submandibular, sublingual, and lacrimal glands, nasal mucosa, and the gag reflex.
- The glossopharyngeal nerve (Cranial Nerve IX) innervates the parotid gland.
- The vagus nerve (Cranial Nerve X) regulates the viscera of the neck, thorax, foregut, midgut, and gastrointestinal tract.
- The sympathetic outflow originates from the thoracolumbar outflow, specifically the T1-L2 spinal cord levels, and reaches the spleen, smooth muscle, and glands through the thoracic and lumbar splanchnic nerves.
- The sympathetic chain ganglia (paravertebral ganglia) are located in the sympathetic trunk and contain the cell bodies of preganglionic neurons. These neurons send fibers to other ganglia for synapses, and postganglionic fibers continue into head and neck tissues.
- Prevertebral ganglia (collateral ganglia) lie around the origins of the large branches of the abdominal aorta. Some preganglionic sympathetic fibers pass through the sympathetic trunk and synapse at these ganglia, while others synapse directly in the same level paravertebral ganglia.
- Postganglionic fibers leave the sympathetic trunk via a gray rami communicans and distribute to effector tissues through peripheral branches of the anterior and posterior rami of the same spinal nerve.
- The sympathetic outflow can follow various courses, including synapsing in higher level paravertebral ganglia, descending to synapse in lower paravertebral ganglia, synapsing directly in a paravertebral ganglion at the same level, or traveling without synapsing to prevertebral ganglia.
- Postganglionic fibers from the superior cervical ganglion innervate the dilator pupillae, smooth muscle of arteries, and head sweat glands, while those from the middle cervical ganglion innervate the heart, trachea, bronchi, and lungs.
- The sympathetic outflow can also be distributed through splanchnic nerves, such as the greater, lesser, and least splanchnic nerves, which reach various organs in the abdominal and pelvic cavities.
- The adrenal medulla is an exception to the sympathetic outflow, as it releases epinephrine and norepinephrine directly into the bloodstream without synapsing.
- Horner's syndrome is a clinical syndrome caused by damage to the superior cervical sympathetic ganglion or the fibers arising from that ganglion. Symptoms include pseudoptosis, miosis, enophthalmos, anhidrosis, and flushing of the face on the affected side.
- White and gray rami communicantes are nerves that connect two other nerves, carrying postganglionic and preganglionic fibers, respectively. They differ in myelination.
- The sympathetic fibers reach the end organ through various pathways, including synapsing in paravertebral or prevertebral ganglia, directly innervating the adrenal medulla, or traveling without synapsing to prevertebral ganglia.
- The sympathetic trunk, consisting of paravertebral ganglia, is the primary pathway for the sympathetic outflow. It contains 22-23 ganglia, including the ganglion impar, which shows patterns of synapsing of sympathetic fibers.
- Preganglionic sympathetic outflow fibers travel through the sympathetic trunk, originating from the spinal cord. White rami communicantes carry preganglionic fibers, while gray rami communicantes carry postganglionic fibers.
Test your knowledge of the divisions and functions of the autonomic nervous system with this quiz. Explore topics such as the sympathetic and parasympathetic divisions, motor innervation of organs and glands, and involuntary responses related to homeostasis.
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