Module 10 - Autonomic Nervous System Flashcards
What kind of contractions does the somatic nervous system cause?
voluntary (contraction of the skeletal muscles)
What kind of contractions does the autonomic nervous system cause?
involuntary (contraction of cardiac and smooth muscle as well as glandular tissue)
In the autonomic nervous system, does stimulation excite or inhibit its effector?
both
How many lower neurons does the somatic nervous system have and where does it travel?
one; travels from the spinal cord to the effector muscle
What is dual innervation?
when target effectors receive innervation from both the sympathetic and parasympathetic divisions - the situation we are in depends on which division is most active
What is the preganglionic neuron?
the first neuron in the pathway running from the spinal cord to the ganglion to synapse with the second neuron
What is the postganglionic neuron?
the second neuron in the pathway, running from the ganglion to the effector
In what nervous system division do the ganglia sit close to the spinal cord?
the sympathetic system
The sympathetic division has a short ____________ axon and a long __________
preganglionic; postganglionic
In the somatic NS, the lower motor neurons have what kind of myelination if any?
highly myleinated
Does the somatic nervous system have fast or slow conduction speed?
Fast
In the autonomic NS, the axons have what kind of myelination if any?
contains lightly myelinated or unmyelinated axons
The autonomic NS has what kind of conduction speed?
slow
Which NS division has pathways that originate from the thoracic and first two lumbar levels of the spinal cord?
The sympathetic NS
Which NS division pathways originate from the brainstem, traveling to effectors via cranial nerves, or from sacral levels S2-S4 in the spinal cord
The parasympathetic NS
The sympathetic division has a short ____________ axon and a long __________
preganglionic; postganglionic
In what NS division are the ganglia located either near or in the target organ?
the parasympathetic division
What are terminal ganglia?
cell bodies that are located near the target organ
What are intramural ganglia?
cell bodies that are located within the wall of the target organ
Which division can only have a very local effect and why?
The parasympathetic division because the postganglionic system is really short – can’t travel far from the ganglion because its so short
Which division has a more widespread effect and why?
the sympathetic; two postganglionic neurons that synapsed in the ganglion with the same preganglionic neuron can travel to effector tissues that are further from each other as well as the adrenal gland can secrete hormones into the blood stream
What is a plexus?
a web of intertwining axons and nerves traveling to their destination; a plexus will contain preganglionic parasympathetic fibers and postganglionic sympathetic fibers
What are neurotransmitters?
signaling molecules released at synapses
In the parasympathetic division, Acetylcholine is secreted in which two synapses?
-Synapse between the preganglionic and postganglionic neurons
-Synapse between the postganglionic neuron and the effector
In the sympathetic nervous system, where is Acetylcholine secreted? Norepinephrine?
-Synapse between the preganglionic and postganglionic neurons = Acetylcholine
-Synapse between the postganglionic neuron and the effector = Norepinephrine
Which NS division involves neurons that originate in the brainstem and the sacral spinal cord?
parasympathetic
Describe the vagus nerve?
cranial nerve X, carries parasympathetic fibers to organs of the thorax and abdomen, cardiac plexus through the superior mesenteric plexus
What are preganglionic axons from the sacral region originating from the S2-S4 level of the spinal cord called?
pelvic splanchnic nerves
What are the three main plexus’s in the thorax?
-cardiac
-pulmanory
-esophageal
What is the esophageal plexus?
Fibers traveling to portions of the esophagus; inhibit or allow digestion
What is the pulmonary plexus?
Fibers traveling to the lungs and bronchi; will increase or decrease respiratory rate
What is the cardiac plexus?
Fibers traveling to the heart; will slow or increase HR
Which two plexus’s are involved in the abdomen?
-celiac plexus
-superior mesenteric plexus
What is the celiac plexus?
fibers that travel to organs of the foregut (alimentary tract organs from the very inferior esophagus through the first two parts of the duodenum, also the liver, pancreas, and gallbladder)
What is the superior mesenteric plexus?
fibers that travel to the midgut organs (third part of the duodenum through the first two thirds of the transverse colon)
What do the pelvic splanchnic nerves (S2-S4) do?
These nerves supply the distal aspect of the alimentary (digestive) tract and pelvic organs.
What is the inferior mesenteric plexus?
fibers that travel to the hindgut organs (last two thirds of the transverse colon to the rectum)
What is the hypogastric plexus?
fibers that travel to pelvic organs, including the bladder and reproductive organs.
Which division of the NS involves neurons that originate from the lateral horns of the thoracic and first two lumbar segments of the spinal cord?
sympathetic
What are the sympathetic chain ganglia?
a network of the majority of ganglia of the sympathetic system
What is the sympathetic chain (trunk)?
where the sympathetic chain ganglia are located; runs alongside the vertebral column
What are the superior, middle, and inferior cervical ganglia?
the three ganglia extend superiorly past the T1 level.
What are the prevertebral ganglia? What organs do they control?
situated anterior to the vertebral column and receive inputs from splanchnic nerves; they are associated with controlling organs in the abdominal cavity
What are the three prevertebral ganglia?
The celiac ganglion, the superior mesenteric ganglion, and the inferior mesenteric ganglion.
What is referred pain?
when you feel pain in a part of your body that is different from where the actual injury or source of pain is located
Describe the white rami communicantes
preganglionic sympathetic axons of T1-L2 spinal nerves; myelinated (EVERY pathway uses)
Describe the gray rami communicantes
postganglionic sympathetic axons from the sympathetic trunk to the spinal nerve; unmyelinated
What occurs in the spinal nerve pathway?
-only pathway that involves the gray rami communicantes
-uses the spinal nerve and its branches to get out to its targets in the skin (heading to integument structures)
-innervates the arrector pili muscles, allowing our hair to “stand up,” our sweat glands to increase sweating for heat dissipation, and the blood vessels in our skin, causing vasodilation to cool blood at the surface of the body (heat dissipation)
What occurs in the postganglionic sympathetic path?
-after entering the sympathetic chain from thoracic levels T1-T5, these fibers ascend to the middle and inferior cervical ganglia where they synapse
-From there they simply exit the sympathetic chain and travel to the following plexuses: cardiac (increase HR), pulmonary (increase respiratory rate), and esophageal (inhibit digestion)Wh
What occurs in the Splanchnic nerve pathway? *most complex pathway
-controls the functions of the gut and pelvic organs. The splanchnic nerves include the greater, lesser, and least splanchnic nerves
-the greater splanchnic nerve (T5-T9) travels to the celiac ganglion. postganglionic fibers join the celiac plexus and travel to organs of the foregut
-the lesser splanchnic nerve (T10-T11) travels to the superior mesenteric ganglion. postganglionic fibers join the superior mesenteric plexus and travel to the midgut organs
-the least splanchnic nerve (T12) sends fibers either to the superior mesenteric ganglion or the inferior mesenteric ganglion
-the lumbar splanchnic nerves (L1-L2) travel to the inferior mesenteric ganglion. postganglionic fibers join the inferior mesenteric plexus and travel to the hindgut organs
-Sacral splanchnic nerves emerge from the sacral extension of the sympathetic chain. Unlike the other splanchnic nerves, they have their synapse in the sacral sympathetic chain ganglia, and the splanchnic nerves that emerge are postganglionic. They join the hypogastric plexus to innervate pelvic organs
What occurs in the adrenal medulla pathway?
-does not have ganglion
-the axons that originate in the spinal cord travel to the adrenal medulla, the interior portion of the adrenal gland
-drenal medulla releases the hormone norepinephrine into the bloodstream, using the blood rather than the postganglionic neurons to communicate with target structures
What three zones is the cortex divided into?
the zona glomerulosa, the zona fasciculata, and the zona reticularis
Why are the hormones secreted by the adrenal cortex important?
important for the regulation of the long-term stress response, blood pressure and blood volume, nutrient uptake and storage, fluid and electrolyte balance, and inflammation.
What is the adrenal medulla?
neuroendocrine tissue that secretes epinephrine and norepinephrine in response to sympathetic stimulation
In order, the foregut includes which 6 organs?
Lower esophagus, stomach, gallbladder, liver, spleen, duodenum (1st and 2nd parts)
What organ is NOT a digestive organ?
the spleen
In order, the midgut includes which 7 organs?
Duodenum (3rd and 4th parts), jejunum, ileum, cecum, appendix, ascending colon, transverse colon (proximal 2/3)
In order, the hindgut includes which 4 organs?
Transverse colon (distal 1/3), descending colon, sigmoid colon, rectum
What is another name for the parasympathetic division?
Craniosacral
What is another name for the sympathetic division?
Thorracolumbar
