Autonomic Nervous System

What component of the nervous system is represented by the autonomic nervous system?

Visceral component

What tissues are directly innervated by the autonomic nervous system?

Secretory glands, cardiac muscle, and smooth muscle

What homeostatic role is served by the autonomic nervous system?

Control of the internal environment

How are autonomic functions related to somatic nervous-system functions?

They are closely integrated

What is the highest central integration station of the autonomic nervous system?

Hypothalamus

What are the two mechanisms by which the hypothalamus regulates autonomic function?

Endocrine regulation through the hypophysis and neural regulation through descending pathways

Which brainstem structures act as central autonomic centers?

Cranial nerve nuclei and respiratory and vasomotor centers of the reticular formation

Which spinal-cord region contains autonomic preganglionic neurons?

Lateral horn of gray matter

Which limbic structures contribute to central autonomic control?

Amygdala and rhinencephalon

Which cortical areas contribute to central autonomic control?

Prefrontal and insular cortex

What structural unit underlies peripheral autonomic function?

Autonomic reflex arc

What receptors detect smooth-muscle tension in autonomic reflexes?

Mechanoreceptors

What receptors detect visceral pain?

Visceral free-nerve-ending nociceptors

Where are autonomic baroreceptors located?

Vascular adventitia

Which structures contain autonomic chemoreceptors?

Aortic and carotid bodies

What type of neurons form the afferent limb of autonomic reflexes?

Pseudounipolar sensory-ganglion neurons

What are the two efferent neurons of an autonomic pathway?

Preganglionic and postganglionic neurons

Where are autonomic preganglionic neurons located?

Visceral efferent brainstem nuclei and lateral gray columns of the spinal cord

What is the myelination status of autonomic preganglionic fibers?

Finely myelinated type B fibers

Which neurotransmitter is released by sympathetic preganglionic neurons?

Acetylcholine

Which neurotransmitter is released by parasympathetic preganglionic neurons?

Acetylcholine

What is the myelination status of most autonomic postganglionic fibers?

Unmyelinated type C fibers

How do postganglionic neurons compare numerically with preganglionic neurons?

They are more numerous

How many postganglionic neurons can one preganglionic neuron innervate?

About 15-20

Why can autonomic preganglionic divergence produce widespread effects?

One preganglionic neuron synapses with multiple postganglionic neurons

Which neurotransmitter is released by parasympathetic postganglionic neurons?

Acetylcholine

Which neurotransmitter is released by sympathetic postganglionic neurons?

Norepinephrine

What are the three classical divisions of the autonomic nervous system?

Sympathetic, parasympathetic, and enteric divisions

What is the enteric nervous system?

A network of neurons in the wall of the gastrointestinal tract

According to the lecture, what autonomic innervation pattern is typical of target structures?

Both sympathetic and parasympathetic innervation

What vascular effect is produced by sympathetic activity in the skin?

Constriction of cutaneous arteries

How does sympathetic cutaneous vasoconstriction alter systemic blood distribution?

Increases blood supply to the heart, muscles, and brain

What is the effect of sympathetic activity on heart rate?

Cardiac acceleration

What is the effect of sympathetic activity on arterial blood pressure?

Increases blood pressure

What is the sympathetic effect on sphincters?

Contraction

What is the sympathetic effect on intestinal peristalsis?

Depression

What metabolic role is served by sympathetic activity?

Mobilization of body energy stores

What is the parasympathetic effect on heart rate?

Cardiac slowing

What is the parasympathetic effect on intestinal glandular activity?

Increases secretion

What is the parasympathetic effect on intestinal peristalsis?

Increases peristalsis

What metabolic role is served by parasympathetic activity?

Conservation of body energy stores

What are the three major autonomic outflow systems?

Cranial, thoracolumbar, and sacral outflows

What spinal levels form the sympathetic thoracolumbar outflow?

T1-L3

Where are sympathetic preganglionic neurons located?

Lateral horn of the spinal cord

What structure is reached by sympathetic preganglionic fibers after leaving the spinal cord?

Sympathetic trunks

What type of ganglia form the sympathetic trunks?

Paravertebral ganglia

What are the ganglia of the sympathetic trunk called?

Ganglia trunci sympathici

What fibers connect adjacent sympathetic trunk ganglia?

Interganglionic rami

What nerves carry sympathetic fibers from the trunk toward prevertebral ganglia?

Splanchnic nerves

What type of ganglia are located anterior to the vertebral column in the sympathetic system?

Prevertebral ganglia

Where is the cervical sympathetic trunk located?

On prevertebral fascia behind the carotid sheath

What are the three cervical sympathetic ganglia?

Superior, middle, and inferior cervical ganglia

What is another name for the inferior cervical sympathetic ganglion?

Stellate or cervicothoracic ganglion

Which spinal nerves provide white rami carrying cervical sympathetic preganglionic fibers?

Upper three thoracic spinal nerves

Along which vessel does the jugular nerve from the superior cervical ganglion travel?

Internal jugular vein

Which structures are supplied by laryngopharyngeal branches of the superior cervical ganglion?

Carotid body and pharyngeal plexus

Which cardiac branch arises from the superior cervical ganglion?

Superior cardiac nerve

Which plexus is formed by the internal carotid nerve?

Internal carotid plexus

Which plexus is formed by external carotid nerves?

External carotid plexus

At what vertebral level is the middle cervical ganglion usually found?

C6

Which cardiac branch arises from the middle cervical ganglion?

Median cardiac nerve

Which plexus receives branches from the middle cervical ganglion?

Thyroid plexus

Which structure links the inferior cervical ganglion with the subclavian region?

Ansa subclavia

Which plexus carries inferior cervical sympathetic fibers to the upper limb?

Subclavian plexus

Which autonomic functions are supplied to the upper limb through the subclavian plexus?

Piloarrector, vasomotor, and sudomotor functions

Which cardiac branch arises from the inferior cervical ganglion?

Inferior cardiac nerve

Which nerve from the inferior cervical ganglion contributes sympathetic fibers to the pineal body?

Vertebral nerve

How many ganglia are usually present in the thoracic sympathetic trunk?

Eleven

Which thoracic organs receive sympathetic innervation from the thoracic sympathetic trunk?

Heart, bronchi, esophagus, and great vessels

Which thoracic splanchnic nerve arises from thoracic levels T6-T9?

Greater splanchnic nerve

Which thoracic splanchnic nerve arises from thoracic levels T10-T11?

Lesser splanchnic nerve

Which thoracic splanchnic nerve arises from T12?

Least splanchnic or renal nerve

Which ganglia are located in the upper part of the coeliac and aorticorenal region?

Coeliac and aorticorenal ganglia

Which splanchnic nerve reaches the upper part of the coeliac and aorticorenal ganglia?

Greater splanchnic nerve

Which splanchnic nerve reaches the aorticorenal ganglion?

Lesser splanchnic nerve

What is the largest major autonomic plexus?

Coeliac plexus

At which vertebral levels is the coeliac plexus located?

T12-L1

Which nerves join the coeliac plexus?

Greater and lesser splanchnic nerves plus vagal and phrenic branches

What is the phrenic plexus?

Superior extension of the coeliac ganglion

Which plexus continues inferiorly from the coeliac plexus?

Superior mesenteric plexus

Where is the superior mesenteric ganglion located?

Above the origin of the superior mesenteric artery

What is another name for the abdominal aortic plexus?

Intermesenteric plexus

Where is the abdominal aortic plexus located?

Between the origins of the superior and inferior mesenteric arteries

What autonomic fibers form the abdominal aortic plexus?

Sympathetic and parasympathetic branches from the coeliac plexus

Which plexuses connect with the abdominal aortic plexus?

Gonadal, inferior mesenteric, iliac, and superior hypogastric plexuses

What is another name for the superior hypogastric plexus?

Presacral nerve

Which sympathetic nerves contribute to the superior hypogastric plexus?

Third and fourth lumbar splanchnic nerves

Which parasympathetic nerves contribute to the superior hypogastric plexus?

Pelvic splanchnic nerves

Which sympathetic nerves contribute to the inferior hypogastric plexus?

Sacral splanchnic nerves

Which parasympathetic nerves contribute to the inferior hypogastric plexus?

Pelvic splanchnic nerves

What plexus arises from the inferior hypogastric plexus to supply pelvic viscera?

Pelvic plexus

What do the pelvic plexuses innervate?

All pelvic viscera

What is the source of the inferior hypogastric nerves?

Ascending fibers from the inferior hypogastric plexus

Which nerves comprise the abdominal and pelvic sympathetic outflow?

Lumbar and sacral splanchnic nerves

Which cranial parasympathetic nucleus supplies the oculomotor nerve?

Edinger-Westphal nucleus

Which cranial parasympathetic nuclei supply salivary pathways?

Superior and inferior salivatory nuclei

Which cranial parasympathetic nucleus supplies vagal pathways?

Dorsal motor nucleus of the vagus

What spinal levels form the sacral parasympathetic outflow?

S2-S4

Which cranial nerves carry parasympathetic preganglionic fibers?

III, VII, IX, and X

Which spinal nerves carry sacral parasympathetic preganglionic fibers?

S2-S4 spinal nerves