Lecture 17 Flashcards
Which are the three main parts of the autonomic nervous system (ANS)
Sympathetic, Parasympatheic, and Enteric
Which part of the ANS is the “rest and digest” branch?
Parasympathetic
Why is the rest and digest branch also described as “craniosacral”?
Because the cell bodies of the preganglionic nerve fibers are located in the brain stem and the sacral portion of the spinal cord.
Where are the postganglionic fibers located in the parasympathetic nervous system?
In the wall of the target organ.
Name 5 examples of organs innervated by the parasympathetic NS?
Heart, lungs, small intestine, stomach, kidneys
Which part of the ANS is the “fight or flight” branch?
Sympathetic
Anatomically, how can the “fight or flight” branch also be described?
Thoracolumbar
Name 5 organs innervated by the sympathetic nervous system
Adrenal gland, pancreas, heart, lungs, liver
Where are the preganglionic and postganglionic cell bodies of the sympathetic NS located?
Preganglionic: in the lateral horn of the thoracolumbar spinal cord.
Postganglionic: cell bodies are located in the ganglia of the sympathetic chain that runs parallel to the spinal cord. They are also located in the celiac ganglia and hypogastic ganglia.
What are the two main parts of the enteric nervous system?
Myenteric plexus and submucosal plexus
What si the function of the Myenteric (Auerbach’s) plexus?
Muscle tone, rhythmic contraction, peristaltic movements of the GI tract
What is the function of the Submucosal (Meissner’s) plexus?
Secretion, Absorption, localized contractions
What is the main neurotransmitter in the enteric NS?
Seratonin
What is the neurotransmitter in all preganglionic neurons of the ANS?
Acetycholine
Which receptor activates all postganglionic neurons?
Nicotinic Acetycholine Receptor
Which neurotransmitter is used in postganglionic neurons of the parasympathetic nervous system?
Acetycholine
What kind of neurotransmitter receptors are found on target tissues of the parasympathetic nervous system?
Muscarinic acetycholine receptors
How are the receptors of the parasympathetic nervous system target tissues numbered and what does it tell you?
M1, M2, M3, M4, M5
Odd-numbers muscarinic receptors are excitatory and are located in M1: neuronal; M3: glands and smooth muscle
Even-numbered are inhibitory and M2 is located in cardiac muscles.
In contrast to the parasympathetic nervous system, what is the neurotransmitter used by postganglionic neurons of the sympathetic nervous system?
Norepinephrine
Name the neurotransmitter receptors on sympathetic nervous system target tissues, and what is one exception?
Adrenergic receptors (Alpha 1, alpha 2, beta 1 and beta 2). The exception is sweat glands which have mACHR and are stimulated by acetycholine rather than norepinephrine.
Which receptors does epinephrine activate and what are its effects in target tissues?
Epinephrine non-selectively activates adrenergic receptors but the beta-2 receptors on postganglionic neurons/cells are selective for EPI.
It’s effects on target tissues are: increased cardiac output, dilate bronchi, constrict blood vessels to skin and viscera, dilate blood vessels to skeletal muscles, increase fatty-acid mobilization, increase glycogenolysis in liver, increase release of ACTH and TSH, and decrease intestinal motility. It will also relax bladder muscles and constrict bladdder sphincter.
What are “NANCs”?
They are non-adrenergic, non-cholinergic transmitters that can be released by the ANS.
Examples: Serotonin, ATP, and nitric oxide (NO)
Which body functions are controlled by the ANS?
All homeostatic body functions.
What are examples of the opposing effects of the sympathetic and parasympathetic nervous systems?
Bladder: PNS constricts bladder muscles and relaxes urinary sphincter. SNS has the opposite effects.
Bronchi: SNS dilates bronchi, PNS constricts bronchi
Intestines: SNS decreases intestinal motility, PNS increases it.
