Autonomic Nervous System and Visceral Sensory Neurons

What is the definition of the sympathetic division?

"Fight, flight, or fright" activated during exercise, excitement, and emergencies

What is the definition of the parasympathetic division?

"Rest and digest" concerned with conserving energy.

What three prevertebral ganglia synapse on the abdominal aorta?

1. Celiac 2. Superior mesenteric 3. Inferior mesenteric

What two differences does the autonomic nervous system?

1. Chain of two motor neurons (preganglionic neuron--CNS to ganglia and postganglionic neuron--ganglia to targets) 2. Conduction is slower due to thinly or unmyelinated postganglionic axons

What are two points about the cranial outflow of the parasympathetic division?

1. Comes from the brain and nuclei of cranial nerves (III, VII, IX, and X) 2. Innervates organs of the head, neck, thorax and abdomen

What are five points about the sacral outflow of the parasympathetic division?

1. Emerges from S2-S4 2. Innervates organs of the pelvis and lower abdomen 3. Pre-ganglionic cell bodies are located in visceral motor region of spinal gray matter (lateral horns) 4. Axons run in ventral roots to ventral rami that forms the pelvic splanchnic nerves that run through the inferior hypogastric plexus 5. Post-ganglionic cell bodies are located: intramurally (inside the walls of the organs)

What are the three thoracic splanchnics?

1. Greater splanchnic nerve 2. Lesser splanchnic nerve 3. Least splanchnic nerve

What are the three purposes of the ANS?

1. Innervates smooth muscle, cardiac muscle, and glands 2. Regulates visceral functions such as heart rate, blood pressure, digestion, urination 3. The general visceral motor division of the PNS

Two points about the sympathetic pathways to the body periphery?

1. Innervates sweat glands, arrector pili muscles, peripheral blood vessels 2. Pre- to post- synapse is within the sympathetic chain at or near the vertebral level of the target cells

What are four points about the basic organization of the sympathetic division?

1. Issues from T1-L2 2. Preganglionic fibers form the lateral horn of gray matter of the spinal cord 3. Supplies visceral organs and structures of superficial body regions 4. Contains more ganglia than the parasympathetic division

What are three points about the sacral outflow of the parasympathetic division?

1. Lateral horns of spinal gray mater (S2, S3, S4) 2. Supplies remaining abdominal and pelvic organs 3. Pelvic splanchnic nerves

What are six points about the sympathetic trunk ganglia?

1. Located on both sides of the vertebral column 2. Linked by short nerves into sympathetic trunks 3. Joined to ventral rami by white and gray rami communicantes 4. Generally a ganglion at each vertebral level 5. Fusion of ganglia in a few spots--> fewer ganglia than spinal nerves. Only 3 cervical (superior, middle, inferior). Superior cervical ganglion is usually the largest 6. Fusion of inferior cervical ganglion with first thoracic= "stellate" ganglion

What four places do the preganglionic fibers run in the parasympathetic division?

1. Oculomotor nerve III (spincter pupillae m.) 2. Facial nerve VII (lacrimal gland, nasal mucosa, submandibular and sublingual salivary glands) 3. Glossopharyngeal nerve IX (parotid alibary gland) 4. Vagus nerve X

What are the two divisions of visceral motor?

1. Parasympathetic division 2. Sympathetic division

What are four points about prevertebral ganglia?

1. Unpaired, not segmentally arranged 2. Occur only in abdomen and pelvis 3. Lie anterior to the vertebral column on the surface of the aorta (near the branches of major arteries) 4. Primary collateral ganglia are celiac, superior mesenteric, inferior mesenteric, inferior hypogastric

What is the definition of the ANS?

A system of motor neurons

What neurotransmitter is released by the parasympathetic postganglionic axons?

Acetylocholine (cholinergic)

What does the sympathetic pathways to the abdominal organs inhibit?

Activity of muscles and glands in visceral organs

What is the anatomical name of the parasympathetic division?

Also called the carniosacral division.

What do postganglionic fibers do in sympathetic pathways to the head?

Associate with large arteries and are carried to glands, smooth muscles (like the dilator pupillae) and vessels throughout the head

What is the purpose of the sympathetic and parasympathetic divisions?

Chains of two motor neurons that innervate mostly the same structures that cause opposite effects.

Where are preganglionic cell bodies located in the parasympathetic division?

Cranial nerve nuclei in the brain stem

Where do the pre-ganglionic cell bodies of the parasympathetic division lie in the thorax?

Dorsal motor nucleus of X

What are the post ganglionic cell bodies are located in the parasympathetic division?

Four ganglia in the head and upper neck 1. Ciliary ganglion (III) 2. Pterygopalatine ganglion (VII) 3. Optic ganglion (IX) 4. Submandibular ganglion (VII). Intramurally in the thorax and abdomen (X)

Where do the postganglionic fibers proceed from in the sympathetic pathways to the pelvic organs?

From plexus to pelvic organs

Where do preganglionic fibers originate in the sympathetic pathways to the abdominal organs?

In spinal cord (T5-L2). Pass through adjacent sympathetic trunk ganglia (NO SYNAPSE) Leave the sympathetic chain as splanchnic nerves such as the thoracic and lumbar splanchnic nerves.

What do preganglionic fibers originate in sympathetic pathways to the head?

In spinal cord from the lateral horns (still motor, ventral root) and travel through white ramus to sympathetic chain and fibers ascend in the sympathetic trunk but synapse in superior cervical ganglion

What is the anatomic name of the sympathetic division?

Issue from different regions of the CNS. Also called the thora-columbar division. Through the spinal cord.

Where do the pre-ganglionic cell bodies of the parasympathetic division lie in the abdomen?

Lateral horn of S2, 3, 4

What is the abdominopelvic sympathetic pathways of the stomach/liver/gallbladder/spleen?

Lateral horn to ventral root to spinal nerve in the ventral ramus to the white ramus to the sympathetic chain to the greater splanchnic nerve to the celiac gnaglion to synapse to follow celiac trunk to follow artery to target

What are the general visceral motor functions?

Motor innervation of smooth muscle, cardiac muscle, and glands; equivalent to autonomic nervous system.

What neurotransmitter is released by the sympathetic postganglionic axons?

Nor epinephrine (adrenergic)

What two differences does the somatic motor system have?

One motor neuron extends from the CNS to skeletal muscle. Axons are well myelinated, conduct impulses rapidly

Where do preganglionic fibers originate in the sympathetic pathways to the pelvic organs?

Spinal cord. Some fibers synapse in sympathetic trunk. Other preganglionic fibers synapse in prevertebral ganglia such as the inferior mesenteric and the inferior hypogastric

What are the general visceral sensory functions?

Stretch, pain, temperature, chemical changes, and irritation in viscera; nausea and hunger

How do the two divisions differ in branching of axons?

Sympathetic-high branched, influences many organs Parasympathetic-fewer branches, localized effect

How do the two divisions differ in length of postganglionic fibers?

Sympathetic-long Parasympathetic-short

What happens if synapse doesn't occur in the sympathetic chain?

They move out of the chain and synapse later in prevertebral ganglia (some call them collateral or pre-aortic)