Parasympathetic vs. Sympathetic

[Music of People’s Court: DA-da-da, da-da-DA-da…]

Court reporter: Here we are outside Judge Wapner’s People’s (Physiology) Court, listening in on the divorce trial of Parasympathetic vs. Sympathetic, to see if they can resolve their “irreconcilable differences.” We all know that “When opposites attract, eventually you end up in DIVORCE COURT”

Ted: All rise for the honorable Judge Peterson.

Judge: Please be seated. Let’s begin the hearings for Parasympathetic vs. Sympathetic nervous systems. I believe both sides have filed ‘irreconcilable differences’ as the reason for all of us being here today, and we also have a custody dispute over the enteric nervous system. Exhibit A on the wall behind me summarizes the main points of each side. Would the lawyers representing the clients please begin presenting their evidence?

Para: Let me start by explaining a bit of the anatomy of my client your honor. My client, parasympathic, stems from the brain. Specifically, cranial nerves 3, 7 ,9 , and 10. A noble place to be from. [Refer to Exhibit B here.]

Sym: This is true your honor, but the lawyer is forgetting about Parasympathetic’s other home, the sacrum- commonly known as the butt!

Para: Well, at least that is better than the thoracic lumbar region ( T1- L2), where the sympathetic stems from. He is also organized in something called the sympathetic chain ganglia. You don’t want to know what their function is.

Sym: This is also true your honor and something my client is not all too proud of. He did not have what many would consider a typical upbringing, and was raised in the lumbar thoracic region of the body. A bit of a troubled past, and for that your honor- like his name applies- please allow him some sympathy (drum roll for that amazing joke!)

Judge: All right, enough background, what are the alleged actions of the two parties?

Para: your honor, my client knows her role in the body and doesn’t mess around. When she acts, she acts with precision on specific target organs in the body; as a result of postganglionic fibers synapsing on the target organ.

Sym: It is good to be specific and all, your honor, but because of my clients close ganglia anatomical association, he can tie the entire unit system together so that they tend to act as a single unit. Unlike the parasympathetic which are made up of relatively independent components.

Para: Differences aside your honor, one thing we both agree in is that both of us use acetylcholine as the major neurotransmitter released between pre- and post ganglionic neurons in the autonomic ganglia. [Refer to Exhibit B here (again)]

Sym: True true…but the similarity with acetylcholine end there. My client, sympathetic, uses norepenephrine as the major transmitter between the post-ganglionic neuron and the effecter cell. In the Parasympathetic division, acetylcholine is the major neurotransmitter between the postganglionic neuron and the effector cell.

Para: oh yeah, what about your clients ‘special friend’ that you see from time to time…I believe you have sole innervation of her…what’s her name again? Does adrenal medulla ring a bell?

Sym: Do I sense some jealousy? My client’s relationship with adrenal medulla is strictly professional. It is true, your honor, that my clients preganglionic neurons control the secretion of the adrenal medulla. It lets her release a mixture of 80% epinephrine and 20 % norepinephrine into the blood- all of which aids in the goal of fight or flight. Which helps my client get as far away from her as quickly as possible!

Judge: Enough--extra-sensory accusations were not part of the original claims. What is the essence of your irreconcilable differences?

Para: We’re just getting to this, your honor. We just can’t seem to agree on any action we take when acting on the same organ. We have dual innervations of many of the same organs, but he is usually gung ho and wants to speed things up, my client prefers to take life a bit easier and isn’t so wound up and uptight like sympathetic. My client likes to relax and enjoy the good things in life, like a good meal and glass or wine. (and watching the tube)

Sym: oh yeah, without my clients function of flattening the lens you would not be able to see far away! – and the t.v.!

Para: That’s great, but my client controls the lens to allow you to see near.

Sym: My client’s actions on the heart increases everything from heart rate, contraction, and conduction velocity, while parasympathetic busies its slow self with keeping things nice and easy. Remember that last time my client was chased by a bear? If it was up to you, parasympathetic, we would have just sat there under that tree and been dinner. Nice and easy you say, well it is because of my fantastic fight or flight mechanism that we survived that little episode. [Refer to Exhibit C here]

Para: Oh yeah, well my clients actions contract the lungs!

Sym: mine relax the lungs!

Para: my client increases motility, relaxes the sphincters, and stimulates secretion in the stomach and intestine.

Sym: oh yeah, without my client you would be nothing but a leaky sieve, always secreting…everything opening and running all the time. My client decreases motility, contracts the sphincters, and inhibits digestion throughout the GI tract.

Para: speaking of ‘leaky’, is it not my client that contracts the gallbladder, while you insist on relaxing it?

Sym: sure, but my client inhibits the secretion of the exocrine gland of the pancreas.

Para: without my client no exocrine gland would be stimulated in the first place!

Sym: My client relaxes the bladder wall, and contracts the sphincter!

Para: Mine contracts the bladder wall and relaxes the sphincter.

Judge: Enough of this constant bickering! With all this fighting, you’ve completely overlooked an important aspect of this case—the custody dispute over the enteric nervous system. From what I can tell, the ENS has been operating pretty independently, with neither of you in control of her! You may be interested to know her whereabouts, she hangs out in the submucosal and myenteric plexuses of the GI tract. She’s in league with a large gang of hormones, of which the ringleaders include gastrin, GIP, CCK, secretin, and motilin. While you two think you’ve been in control of all the organs, including the GI tract, these guys have a lock on large parts of GI tract activity… For example, the feedback mechanism from duodenum to stomach that slows gastric emptying; and they influence motility, by regulating the intensity of the pacemaker cells in the stomach and small intestine. From what I understand, those upstart pacemaker cells are behaving in a highly unstable manner, always on the go and won’t listen to anyone else.
So, I’d like to know if either of you can control the enteric nervous system?

Para: well, your honor, with all due respect I must point out that ENS is a highly sophisticated coordinating center that is meant to handle the short reflexes that are part of the GI system, that at times operate without input from the CNS. So, we can coordinate with ENS but we can’t control her.

Judge: Fine, then she will remain independent but continue to coordinate with you. Is there anything else Para and Symp can agree on?

Sym: well, umm….when it comes to reproduction….um… we kinda need each other to function. All I can do is shoot, which usually doesn’t happen unless parasympathetic is helping me point.

Para: truth be told your honor, my client and sympathetic rarely operate independently and the autonomic response generally represents the regulated interplay of both sympathetic as well as parasympathetic.

Judge: so you’re telling me that even though you both do many different things, you both need each other for survival?

Para and Sym: “yes”

Judge: Well, then, this case is closed. I need to move on—the duodenum is suing the stomach for gastric dumping, and the large intestine is suing the small intestine for contaminating its water supply. You’re dismissed.