Anatomy Chapter 17

What does ANS stand for?

Autonomic Nervous System

What is the etymology of autonomic?

 Autos = auto
 Nomos = law

By definition the ANS is purely ________

Motor

How does transmission of a signal from the
CNS to an effector differ between the
somatic and autonomic divisions of the
nervous system (just the most basic
difference)?

It travels through 2 neurons in the ANS, only 1 in the somatic division.

What do we call the first neuron in an ANS
pathway?

Pre-ganglionic neuron

Describe a Pre-ganglionic neuron's axons

Myelinated

What do we call the second neuron in an
ANS pathway?

Ganglionic neuron

What do we call the axons of the second
neuron? Describe them.

 Post-ganglionic axons
 Unmyelinated

What are the two major divisions of the ANS?

 Sympathetic
 Parasympathetic

What is the anatomically based name for the sympathetic division?

Thoracolumbar

What is the functional (laymen’s) name for the sympathetic division?

Fight-or-flight

Where are the cell bodies of the preganglionic sympathetic neurons located?

Lateral horns (of spinal cord) from T1 – L2

What neurotransmitter is generally released by sympathetic post-ganglionic axons?

Norepinephrine

What are the two types of ganglia in the
sympathetic division and where are they
located?

Sympathetic trunk ganglia
 Parallel to vertebral column

Collateral ganglia
 Anterior to abdominal aorta

What carries sympathetic signals from the
spinal nerve to the sympathetic trunk?

White ramus communicans

What carries sympathetic signals, destined
for glands or peripheral blood vessels in the
body wall, which return to a spinal nerve for
distribution?

Gray ramus communicans

How do sympathetic impulses destined for
areas outside region of sympathetic impulse
origination (T1-L2) get to their target?

 Originate from T1-L2
 Enter the sympathetic trunk
 Travel through additional ganglia
 Every spinal nerve has a gray ramus

What do we call the nerves that carry fibers
that have passed through the sympathetic
trunk without synapsing to the collateral
ganglia where they will synapse prior to
innervating abdominopelvic viscera?

Splanchnic nerves

What are the names of the 3 collateral
ganglia?

 Celiac
 Superior mesenteric
 Inferior mesenteric

What endocrine organ is composed of short
post-ganglionic neurons of the sympathetic
division and what neurotransmitters (that
act as hormones) are released?

Adrenal medulla

What are some of the effects of sympathetic
stimulation?

 Increased alertness
 Increased cardiac and respiratory activity
 Increase muscle tone
 Energy mobilization
 Dilate pupils
 Constrict peripheral and visceral vessels
 Stimulate sweat and arrector pili muscles
 Ejaculation

What is the functional (laymen’s) name for
the parasympathetic division?

Rest-and-digest

What is the anatomically based name for the
parasympathetic division?

Craniosacral division

Where are the cell bodies of the preganglionic
parasympathetic neurons
located?

 Brainstem
 S2-S4

What cranial nerves transmit
parasympathetic impulses?

 Oculomotor
 Facial
 Glossopharyngeal
 Vagus

What neurotransmitter is generally released
by parasympathetic post-ganglionic axons?

Ach – acetylcholine

Where are the ganglia located in the
parasympathetic division?

Near or in the wall of the target organ

What are some of the effects of
parasympathetic stimulation?

 Constrict pupils
 Secretion from digestive glands
 Increase GI motility
 Constrict respiratory passages
 Reduction of heart rate
 Arousal

What region of the brain has the most direct
control over the ANS?

Hypothalamus

What region of the brain contains
autonomic reflex centers that control things
such as cardiovascular and respiratory
activity, pupil size, digestive secretion, and
peristalsis?

Medulla oblongata

What aspect of the brain (linked to the
hypothalamus) links emotion and autonomic
function?

Limbic system