Autonomic Nervous System (ANS) - Chapter 18 Flashcards
The ANS governs what kind of actions?
involuntary
Are the functions of the ANS voluntary or involuntary?
involuntary
Which neurons of the ANS innervate smooth and cardiac muscle and glands?
motor neurons
Which neurons can excite or inhibit cells in the viscera?
motor neurons
The first neuron in an ANS pathway is called the what?
preganglionic neuron
The second neuron in the ANS pathway is called the what?
postganglionic neuron
Where is the cell body of the preganglionic neuron located?
brain or spinal cord
Where is the postganglionic neuron housed/located?
within an autonomic ganglion in PNS
The postganglionic axon extends to where?
effector (target) cells
What is the role of the parasympathetic division?
conservation of energy and replenishment of nutrient stores (“rest-and-digest”)
What is the role of the sympathetic division?
preparation of the body for emergencies (“fight-or-flight”)
Describe the length of the pre- and post-ganglionic axons in the sympathetic division.
preganglionic axon = short, postganglionic axon = long
Describe the length of the pre- and post-ganglionic axons in the parasympathetic division.
preganglionic axon = long, post ganglionic axon = short
Which division is responsible for a global response?
sympathetic (“fight-or-flight”)
Which division is responsible for a local response?
parasympathetic (“rest-and-digest”)
Where are ganglionic neurons found? (2 possible locations)
in terminal ganglia close to the target organ or intermural ganglia in the wall of the target organ
Which cranial nerves are part of the parasympathetic division?
- oculomotor nerve (CN III)
- facial nerve (CN VII)
- glossopharyngeal nerve (CN XI)
- vagus nerve (CN X)
The preganglionic neuron cell bodies in the thoracolumbar division of the sympathetic division are housed where?
in lateral horn between T1 and L2
What does the sympathetic trunk ganglia house?
sympathetic ganglionic neuron cell bodies
The cervical portion of the sympathetic trunk is partitioned into 3 ganglia, what are they?
superior, middle, and inferior ganglia
What does the cervical sympathetic ganglia innervate?
structures in the head and neck
The middle and inferior cranial ganglia house what?
neuron cell bodies that extend axons to the thoracic viscera
What does the rami communicantes connect?
sympathetic trunk to each spinal nerve
What does the white rami communicantes contain?
preganglionic sympathetic axons - myelinated
What does the gray rami communicantes contain?
postganglionic sympathetic axons - unmyelinated
What are splanchnic nerves composed of?
preganglionic sympathetic axons that did not synapse in a sympathetic trunk ganglion
What are larger nerves that extend from the sympathetic trunk ganglia? (5)
- greater thoracic splanchnic nerves
- lesser thoracic splanchnic nerves
- least thoracic splanchnic nerves
- lumber splanchnic nerves
- sacral splanchnic nerves
Splanchnic nerves usually terminate where?
prevertebral (collateral) ganglia
Prevertebral ganglia include which ganglia?
celiac ganglia, superior mesenteric ganglia, and inferior mesenteric ganglia
Where is the celiac ganglion located?
adjacent to origin of celiac artery
Where is the superior mesenteric ganglion located?
adjacent to origin or superior mesenteric artery
Where is the inferior mesenteric ganglion located?
adjacent to origin of inferior mesenteric artery
Preganglonic axons of the celiac ganglion carry which nerves?
greater thoracic splanchnic nerves
Postganglionic axons of the celiac ganglion innervate which parts of the body?
stomach, spleen, liver, gallbladder, proximal duodenum, part of pancreas
Preganglionic axons of the superior mesenteric ganglion carry which nerves?
lesser thoracic splanchnic nerves
Postganglionic axons of the superior mesenteric ganglion innervate which parts of the body?
distal duodenum, part of the pancreas, the remainder of small intestine, proximal large intestine, kidneys, part of ureters
Preganglionic axons of the inferior mesenteric carry which nerves?
lumbar splanchnic nerves
Postganglionic axons of the inferior mesenteric ganglion innervate which parts of the body?
distal colon, rectum, urinary bladder, distal ureter, and most reproductive organs
Axons exit the sympathetic trunk ganglia by which 4 pathways?
- spinal nerve pathways
-postganglionic sympathetic nerve pathway - splanchnic pathway
- adrenal medulla pathway
Which 2 pathways are the most common axon exits from the sympathetic trunk ganglia?
- spinal nerve pathway
- postganglionic sympathetic nerve pathway
Spinal cord to effectors; which pathway?
spinal nerve pathway
spinal cord to thoracic cavity, internal organs, and effectors of skin of head; which pathway?
postganglionic sympathetic nerve pathway
spinal cord to abdominal and pelvic organs; which pathway?
splanchnic pathway
spinal cord to direct innervation of adrenal medulla; which pathway?
adrenal medulla pathway
What is the purpose of the adrenal medulla?
release hormones within the bloodstream to promote flight-or-flight response
Which hormones does the adrenal medulla release?
epinephrine and norepinephrine
What are autonomic plexuses?
collections of sympathetic postganglionic axons, paraganglionic and preganglionic axons, and visceral axons
Name autonomic plexuses (5):
- Cardiac plexus
- Pulmonary plexus
- Esophageal plexus
- Abdominal plexus
- Hypogastric plexus
What does the cardiac plexus consist of?
postganglionic sympathetic axons from thoracic sympathetic trunk ganglia and preganglionic axons of vagus nerve
Increasing sympathetic activity of cardiac plexus results in what?
increase heart rate and blood pressure
Increasing parasympathetic activity results in what?
decrease heart rate
What does the pulmonary plexus consist of?
postganglionic sympathetic axons from thoracic sympathetic trunk ganglia and preganglionic axons from the vagus nerve
What does parasympathetic stimulation cause in the pulmonary plexus?
bronchoconstriction and increased mucus gland secretion in bronchial tree
Sympathetic innervation of pulmonary plexus causes what?
brochiodilation
What is dual innervation?
innervation by postganglionic axons from both ANS divisions
What is the antagonistic effect?
actions of the ANS divisions usually oppose each other
What does the esophageal plexus consist of?
preganglionic axons from the vagus nerve
What does parasympathetic activity of the esophageal plexus result in?
coordinates smooth muscle activity during swallowing reflex in inferior wall and cardiac sphincter in inferior esophagus
What is the abdominal aortic plexus composed of?
postganglionic axons projecting from the prevertebral ganglia and preganglionic axons from the vagus nerve
What does the hypogastric plexus consist of?
postganglionic sympathetic axons and preganglionic parasympathetic axons from the pelvic splenic nerve
What does the hypogastric plexus innervate?
viscera within the pelvic region
