Autonomic Nervous System Review

Flashcards covering the functional anatomy, physiology, and organizational structures of the Autonomic Nervous System, including sympathetic, parasympathetic, and enteric divisions.

What is the primary function of the Autonomic Nervous System (ANS)?

Homeostasis.

How does the motor neuron-effector path differ between the Somatic and Autonomic systems?

The Somatic system uses a one cell path (direct), while the Autonomic system uses a two cell path consisting of pre- and post-ganglionic neurons.

Where are the somas of pre-ganglionic and post-ganglionic neurons located in the Autonomic system?

Pre-ganglionic somas are in the Lateral horn of the SC or Brain stem; post-ganglionic somas are in the Autonomic ganglion.

What is the effect of Sympathetic versus Parasympathetic stimulation on the heart rate?

Sympathetic stimulation increases heart rate, while Parasympathetic stimulation decreases it.

Approximately how long does it take to clear catecholamines from the blood after stimulation of the adrenal medullae?

$3-4\,\text{minutes}$.

What percentage of the adrenal medulla's secretion is composed of epinephrine?

$80\%$.

In the sympathetic pre-vertebral ganglia, one pre-ganglionic neuron can synapse on how many post-ganglionic neurons?

As many as $200$ post-ganglionic neurons.

Which spinal segments correspond to the Superior cervical ganglion?

$C1-C4$.

What type of nerve fibers are Sympathetic post-ganglionic neurons?

Unmyelinated C fibres.

Which specific cranial nerves (CN) constitute the Cranial parasympathicus?

$\text{CN III, VII, IX, and X}$.

Which cranial nerve and nucleus are responsible for the innervation of the lacrimal and nasal glands?

The Facial nerve ($\text{CN VII}$) and the Superior salivatory nucleus (synapsing in the Pterygopalatine ganglion).

What is the result of a brain stem transection below the medulla regarding arterial pressure?

Arterial pressure falls to less than one-half normal.

What are the primary functions of the Myenteric and Submucosal (Meissner's) nerve plexuses in the enteric NS?

The Myenteric nerve plexus controls motility, and the Submucosal nerve plexus regulates fluid and ions.

How does very strong Sympathetic Nervous System (SNS) stimulation affect the enteric nervous system?

It inhibits it, causing increased tone of the sphincters and decreased motility and secretion.

Through which structure do Sympathetic pre-ganglionic myelinated B fibres travel to reach the ganglion?

White communicating rami.