Neurology | Parasympathetic Nervous System

iron engineers in this video we're gonna talk about the parasympathetic nervous system now we've already talked about the inter to the autonomic nervous system when we talked about the sympathetic nervous system in detail if you haven't already watched those videos please go watch those videos all right now we're not going to go into extreme extreme detail on each one of these cranial nerves and the reason being is that we've already covered most of the actual cranial nerves in great detail and those individual nerve videos but we're gonna do is we're gonna talk about the cranial outflow because if you remember we said that the parasympathetic nervous system alright the parasympathetic nervous system is primarily going to be what's called cranial sacral outflow okay and what do we mean by that so we said that the parasympathetic nervous system came from specific cranial nerves for example we have what's called cranial nerve three right we have another one cranial nerve what seven we have another one which is going to be cranial nerve nine and then we have another one which is going to be cranial nerve 10 and then their actual names the oculomotor and then we're gonna have facial glossopharyngeal and then we're gonna have Vegas right so these are the cranial nerves these are the ones that have parasympathetic fibers associated with them the other part of the parasympathetic nervous system is going to be the sacral division of the spinal cord so if you remember that was from s2 to s4 so the other part is going to be the sacral a part of the spinal cord so specifically we said that this was going to be from s2 to s4 so we call this collectively together as one big group we say that this is the craniosacral cranial sacral outflow or output okay so that is what we're gonna focus on so in this video we're gonna talk about the third cranial nerve it's affects seventh ninth ten same thing they're effects then we're going to talk about the the fibers of the sacral part of the spinal cord and what organs they innervate and again their overall function before we do that though we have to know because we talked about this in the sympathetic nervous system these guys don't kind of work on their own we have to have some type of structure that controls their activity so if you know there's a specific structure right here and it's called the hypothalamus right and the hypothalamus is actually connected to a structure called the pituitary gland through what's called the infundibulum but what's important to know is that the hypothalamus does have portions that are actually going to be specifically parasympathetic so they do affect the parasympathetic nervous system let's just say for this sake we draw this portion here as though this is the parasympathetic portion of hypothalamus so that's our parasympathetic portion what can happen is this can give presynaptic fibers that can descend downwards and guess what it can do it can give stimulation to this nucleus it can give stimulation to this nucleus this one and this one to stimulate the actual cranial so now let's assume that we stimulated this nerve nucleus right here okay so the third cranial nerve we already know that this is going to be three it has a specific nucleus that's associated with the oculomotor nerve oculomotor nerve you remember has parasympathetic fibers and it also has some atom motor fibers we talked about that but the specific nucleus here for three if you remember it's called the edinger Westfall nucleus the Edinger Westphal nucleus what happens is it takes parasympathetic fibers outwards right and then as it takes these parasympathetic fibers outwards and if you remember parasympathetic fibers they're preganglionic do you remember if they were long or short they're long so you have long preganglionic parasympathetic motor neurons and eventually what happens is they go to a ganglia okay what's a ganglia a ganglia by definition is a group of cell bodies within the peripheral nervous system what is this ganglia that the editor Westfall nucleus the axons of it go to it's specifically called the ciliary ganglion okay so the attagirl Westfall nucleus has axons that come out is the preganglionic long parasympathetic motor neurons they come to a ganglion Styne apps on the ciliary ganglion to be specific then what happens what's another remember we said that these ganglia for parasympathetic they're very specific what type of gangly do we call these when you have long preganglionic which pretty much go to the target we're going to even go into the target organ we call those intramural or terminal ganglia so we're going to say here that this is an example of intramural ganglia okay so it's important to remember because the sympathetic was the one that had the pre vertebral or the pair of vertebral and it didn't have that one exception which would go to the adrenal medulla via the intramural Ganga okay but now parasympathetic it's pretty much all intramural or terminal ganglia okay intramural are terminal and that specific type is the ciliary from that ganglion parasympathetic postganglionic fibers will come out and what happens is they'll pierce through the sclera and then move into like this peri coronal space and what happens is it'll actually give fibers to two different destinations one is actually gonna be the ciliary muscle the other one is going to be the pupil now if you remember we said that the ciliary muscle which is the first destination what happens to this guy so first thing it's going to do is it's going to innervate the ciliary what's gonna happen to the ciliary it's gonna contract now when the silly air is contract does O'Neill's actually become relaxed okay so whenever the silly airs contracts the zonules the suspensory ligaments which are basically connecting to the lens here that becomes very very lacks so the cine Larry's O'Neill's are going to become relaxed when the zonules relaxed what happens in this situation is it allows for this actual lens to become more globular like okay so now the lens is going to become more globular like when the zonules relaxed and the lens becomes globular what is the significance of this the whole significance of this effect right here is to help with what's specifically called near vision okay so it's going to help to undergo what's called accommodation and that accommodation response is going to help us to see things that are nearby so this is gonna help in the process of near vision okay that's the overall response there so it's gonna undergo an accommodation response where it changes the shape of the lens makes it more globular which helps us for a near vision okay the other muscle that it goes to is what's called the sphincter pupil a when it goes to the sphincter pupil a the muscles of the sphincter pupil a when it contracts it acts like a ring okay like a sphincter and when it contracts it squeezes the pupil hole small right so it's trying trying to squeeze the pupil hole and constrict the people making that pupil whole really really really small so by doing that what's that called it's going to cause pupil constriction and if you constrict the pupil that also has an effect with near vision but even more specifically it allows for less light rays to come into the eye right okay so that's the effect there on the eye all right now let's come back over here and let's go to the next one so the next one here which is gonna be a little bit lower within the pons kind of round the pons medulla Junction there's a specific nucleus here this nucleus right here so we said what was this one here called this purple one just so we remember I'm not gonna write the whole darn thing out cuz I don't even know how to spell it very well the editor Westfall nucleus okay the next one though which is that the lower pawns kind around the medulla Junction area there this is called the superior salavat Ori nucleus and this is gonna be for the facial nerve okay superior Salvatori nucleus now what happens with this guy is he's gonna come out right and again he's gonna have long preganglionic axons if you remember going back it was actually what call it what nerve I couldn't became a part of what's called the greater petrosal nerve if you remember alright but again it's actually gonna come out and it's gonna go to a ganglia and what is that ganglia here call this ganglia weird actually sigh laughs is actually has two ganglia to be specific so it's actually show here because if it goes up through the Greater petrosal nerve right it'll come up and supply the lacrimal gland and also some some Palantine glands and some nasal glands but if it goes downward it actually goes a part of the court attempt an eye which actually is going to go to the tongue right specifically for salivation so there's two ganglia if it goes as the greater petrosal nerve it'll come up here that ganglion right here is specifically called the ter ago Palatine ganglia okay that's the tear go pound tied ganglia and then these fibers will come out here and they'll come to specific glandular structures and I'll talk about that in a second but what's the other one the other one remember this one is a part of the greater patrol so nerve the one that goes at at ergo Palatine but if it actually comes do the actual middle ear if you remember there's what's called the posterior canal colliculus anterior canaliculus and then it moves out with the court attempt and then it goes to the tongue area this gangly on here is called the sub mandibular ganglion okay now these guys will come out here and it will go to some specific glands that we're going to talk about now terrico Palantine ganglia remember if i talked about in the sympathetic the sympathetic the postganglionic release norepinephrine and then the sympathetic preganglionic neurons released acetylcholine and the parasympathetic remember the preganglionic and the postganglionic motor neurons both release acetylcholine but you can have different receptors will make a video some time on that about the different types of muscarinic and nicotinic receptors so let's say that if it goes tear go Palantine ganglia what are some of the glands that it's going to go to it can go to specifically it could be the lacrimal glands it could be the nasal glands it could even be the Palatine glands okay so it can innervate a lot of these glands here lacrimal nasal Palatine lids it's going to release acetylcholine that's going to stimulate these cells to start increasing their production of these watery secretions for example lacrimal secretions nasal secretions Palatine secretions so it's going to increase the actual sea creations here so you're gonna have more of this actual tear production you're gonna have more nasal secretions and you're gonna have more Palatine secretions okay so that's the effect there via the tear go pound sign ganglia so now let's say that it comes over here right as a part of the courtesan panel and as it comes a part of the court of Japan I gives all fibers remember that goes to the submandibular ganglia then those postganglionic parasympathetic fibers are going to come over here and they're gonna stimulate specific glandular structures what type of glandular structures these ones are going to be like your sub mandibular and your sub lingual salivary glands right when it goes to these glands what's it going to do it's going to increase the production of saliva so as you start making more of this saliva it's going to be making saliva rich in a lot of different types of enzymes one specific one one specific component of the saliva is going to be what's called salivary amylase we'll talk about this more when we get into the GI but specifically this is important for being able to break down carbohydrates specifically polysaccharides so it's the first side of chemical digestion within the alimentary canal alright alright so now that takes care of that part now we got to go to the next guy okay the next guy over here is this green nucleus this green nucleus is going to be specifically called the inferior Salvatori nucleus right within the medulla now this guy is the glossopharyngeal nerve right the glossopharyngeal nerve is going to give fibers right and if you remember this is the one that goes as the part of the lesser petrosal nerve and then what happens it goes to a specific ganglion and we had a long long pathway for this guy but eventually it gets to a specific ganglia all right this ganglion is code called the otic ganglion okay now the otic ganglion is really important because from here this is going to send the remaining amount of fibers parasympathetic fibers to the last salivary gland one of the big ones on the side of your face right next to the masseter muscle this guy right here is going to be called the parotid salivary gland what it's gonna do is it's gonna stimulate release acetylcholine right onto these actual muscarinic receptors on this specific glynn and let's assume that in this case this gland is the parotid gland so the parotid salivary gland and what is it going to do it's going to stimulate this guy to start increasing the secretions right as it stimulates this guy to increase the salivary secretions again what type of substances will want to have and it'll want to have lots of salivary amylase and what else what else is important for being able to digest food lots of watery secretions you want to really moisten that bolus the food bolus right so whenever you're chewing food you want to have lots of saliva there to mix with the food bowls so not only is it making things that are rich in salivary amylase but it's increasing the actual watery secretion so you want to be a little bit more of a watery secretion okay same thing over here you're going to want to only have salivary amylase here but increase the watery secretions you want to be really be able to lubricate that that food and convert it into a compact mass called a bolus that we can push it back into the oral pharynx area whenever we undergo the deglutition response okay so that covers that guy now for the Big Mama the one who does so darn much this is going to be the dorsal nucleus of Vegas alright so this is where the vagus nerve now the vagus nerve if you don't remember any of these at least remember the vagus nerve he controls pretty much 90% of the parasympathetic responses he controls a lot of different structures 70% of the affarin neurons that are pretty much within the actual abdominal visceral area is gonna be vagus nerve so he controls so much of the parasympathetic flow now this guy again I'm not going to go over every single branch I'm going to keep it very simple and say it has various plexus right so over here one of them is it's gonna go to the lungs specifically the bronchi right now in the bronchi you have smooth muscle right and the smooth muscle is responsible for either constricting the actual bronchial or dilating it now we're resting we're not really worried about being able to get as much ventilation as possible so what are we gonna want to do waste our energy on making our bronchioles dilate no we're gonna want to constrict them all right so what what's gonna happen here is we're gonna come to this actual bronchial so we call this one specifically we call it the pulmonary plexus so we call it the pulmonary plexus and what's the overall effect here on the bronchioles so overall effect here on the bronchioles is you're going to have what's called barranco constriction okay so you're gonna have bronchoconstriction because you're not gonna want to really have those Airways dilator you don't to waste energy on that but another thing if you're resting you're not really worried about mucus production either all right so I mean you're actually you don't wanna when you're in a firefly situation you don't want mucus blocking your Airways right you want to be able to get as much oxygen in but in a parasympathetic situation you're not really gonna be running away from anybody you're gonna be chilling out resting so in that situation you don't care about the mucus production you can go ahead and do it if you want to so there is gonna be an increase in secretions specifically like the mucus secretions okay so there might be some mucus secretions there okay so that's the effect on the lungs okay the pulmonary system what about the heart there is another plexus here another plexus that's actually gonna come over here and it's going to be called the cardiac plexus okay now you know there was many branches we already went over all of that in the vagus nerve video if you haven't seen it go see it but we already have one knowing that the cardiac plexus is going to go to the heart now we have to be very careful because parasympathetic nervous system doesn't really affect the myocardium like the actual contractile cells it affects the nodal cells okay there is some literature that says they can affect some of the atrium muscle cells but not really it's specifically focusing on the nodal cells if you remember some of those structures we said that for the heart all right so for the heart what was the overall effect here it was affecting the SA node and what was the other big one AV node so it was trying to be able to affect these two guys here now if you remember we did say right vagus goes to SA node left Vegas goes to the AV node but what's really important here is what type of effect do they have on these guys so the overall effect of these guys is it tries to be able to decrease their action potentials if you decrease the amount of action potentials this SA node an AV node is sending what's the overall effect that's gonna slow down the heart rate so it's gonna decrease the heart rate so we say it has negative chrono tropic action indra mo tropic action and bath mo trip it meaning can affect various different parts of the conduction system but we're not going to talk about that so again decreases the heart rate overall effective decrease in the heart rate is you can decrease the blood pressure okay so again that's overall effective the decrease the heart rate it can lead to a decrease in the blood pressure alright sweet deal so that covers that part now what else it also gives libraries that can go to the esophagus okay so it also can get fibers here that can go to the esophagus so look at this bad boy here if it goes to the esophagus it's called the esophageal plexus right so I can give off branches here that I've become a part of what's called the esophageal plexus now if you remember there's a part called deglutition there's two phases the oral phase or that we call it the buccal phase and the friend Joe esophageal phase what happens is the esophageal plexus is important for causing the peristalsis the alternating waves of contraction and relaxation within the smooth muscle of the esophagus and the stomach and a lot of the actual GI tract so for here it's going to increase the peristalsis all right so it's going to increase the motility there the esophagus alright so that covers that so we have the pulmonary plexus the cardiac plexus and the esophageal plexus now here's where it gets a little bit tricky because what happens is the esophageal plexus can actually come over here and I can continue and give off like a posterior gastric branches and I can come over here and give off anterior gastric branches to the stomach also to increase the motility of the actual stomach so here it can affect the stomach and if it affects the stomach it's going to increase the motility of the stomach via peristalsis what else could it do to this stomach we're gonna talk about this in another video but you have what's called sub mucosal nerve plexus and a my enteric nervous it can act on those guys to increase the my enteric to increase the motility but it can act on submucosal plexus as well as other cells in this area such as parietal cells and it can cause those fried to make more gastric juices right so it can actually increase secretions all right so it can increase motility it can increase the cretians now here's where it gets a little kind of tricky here what happens is from this guy you're gonna have another structure so I'm gonna I'm not gonna be too crazy here but I'm just gonna say that from I'll say it simply you have another structure here it's mainly from the right Vegas okay and the right Vegas is gonna feed into what's called the celiac plexus okay so the celiac plexus now the celiac plexus which is mainly here I'll put it here inside it's mainly coming from the right Vegas what happens is the celiac place is going to supply a whole bunch of different structures it can give supplies to the kidney some people say that it doesn't but it can give a little bit of effect to the kidney specifically around the blood vessels there and then also the ureter okay it also can give supply to the ascending colon it can give supply to the transverse colon but specifically the proximal two-thirds of the transverse colon it can give supply to the part of the duodenum and even do genome and even ileum right so we can give supply to a lot of different parts of the colon so the ascending colon the transverse colon the proximal half of a proximal two-thirds of it it can even give supply to the pancreas right so can even get supply to the pancreas as well so there's a lot of different structures and if you want I'm not going to take the whole soccer all the way over there but it can't even go to the spleen - okay but I'm not going to take it over this so you know that if overall it can go to the kidney and so with the kidney it's basically going to try to be able specifically its bends it says that it could actually help to increase some of the contractions of the ureter and it can also help to play a role within the urine formation okay the urine formation part is a little controversial but they do say that it can help with a little bit in urine formation and then over here it's supposed to cause the contractions of the ureter okay so it can cause contractions of the ureter okay over here for the colon and for the Jew genome and the ileum and stuff like that what's the overall effect now for the colon specifically for the colon so when we talk about the actual large intestine okay the large intestine this one is more specifically on increasing motility that is its main design okay is to increase the motility alright but for the small intestine like the duodenum the jejunum the ileum it has a little bit of an effect also on secretions and some absorption so it can actually increase motility it can increase secretions and it can help to increase a little bit of the absorption processes okay for the pancreas it actually can act on specific cells in the pancreas you know there was the islet of Langerhans the islet of Langerhans are actually there and you have alpha cells and beta cells remember there are specific cells there they're called pancreatic beta cells it can act on the pancreatic beta cells and it can cause insulin to be released okay so it can help to stimulate the release of insulin it's not a powerful stimulator but it can definitely cause insulin to be released okay another one another branch here let's actually have this guy come in here we're gonna do this one here it's gonna be again a little bit more specific but this guy here all comes from the left Vegas okay this one here which I'm trying to make a little bit thicker here is coming from the left Vegas and that's going to go to the liver and it's going to go to the gall bladder and some of the biliary tree here okay why is this important this one here we need to understand this right here I'm actually gonna kind of write this one here we're gonna have the paddock plexus okay so this is called the hepatic plexus the hepatic plexus is the one that's coming mainly from the left vagus nerve now what happens is the apat ik plexus is going to go to the liver it can help deliver to be able to do a specific specific process one of those processes here is it can stimulate what's called glyco genesis okay because you're resting you're not really worried about your glucose levels being able to increase you're actually focusing on it kind of storing them you're resting you're digesting okay also it can act on the gallbladder let's say that you you just ate right you want to be able to break down that Big Mac all that fat all that different substances so what's it going to do it can actually stimulate gall bladder contractions so it can stimulate gall bladder contractions so it's been found to stimulate glyco Genesis stimulate gall bladder contractions and there's another one here it's kind of a cool one too there's a little muscle here called the apado pancreatic sphincter right or the sphincter of Oddi and what happens is it does have receptors for acetylcholine and if this actual fibers come down here and stimulate the sphincter of Oddi it can actually relax the hepato pancreatic sphincter or the sphincter of Oddi however this is more heavily regulated by a specific type of entire column called cholecystokinin okay Koli sister kind of has more of an effect on the pad of pancreatic sphincter relaxation and gallbladder contraction okay again we'll talk about that when we get into the GI okay but so far we know the basic components the basic branches of the vagus just because it's so much let's have a real quick recap ready pulmonary plexus goes to the bronchioles causes bronchoconstriction increased secretions their cardiac plexus causes a effect on the SA node AV node to decrease the heart rate which can eventually decrease blood pressure the esophageal plexus goes to the esophagus and increases the peristaltic activity there and what else we'll also have the silly act plexus which specifically comes from the right vagus that can help to increase urine formation it can also help to contract the ureters and it can supply the even parts of the stomach here to increase motility and secretions it can supply the duodenum to increase motility secretions and absorption and it can affect the large intestine specifically from the cecum all the way up to the proximal two-thirds of the transverse colon specifically there it's trying to increase motility and it can supply the spleen to okay now to finish her all up alright to come down here we have to finish the last part so the last part here is let's bring down these parasympathetic these presynaptic fibers here I had that in red my red marker so we're gonna come down here right and it's going to stimulate these nuclei here within the sacral region of the spinal cord and if you remember this was going to be s2 s3 s4 now these guys come out and specifically they say that it's in the lateral gray Horn of the spinal cord but they don't there are certain books that'll say that the lateral gray Horn of the spinal cord doesn't really isn't plentiful or isn't in large amount within the sacral region of the spinal cord but for right now we're gonna say lateral gray or now these pelvic splanchnic nerves so these are called your pelvic splanchnic nurse remember don't confuse these with the sacral splanchnic nerves because sometimes people might think Oh sacral region of the spinal cord sacral spikes difference no that was for the sympathetic okay this is for the parasympathetic now these pelvic splanchnic nerves go and supply anything that the vagus didn't supply so for example it'll come here and supply the gonads okay it'll come here and supply thee the trustor muscle of the bladder it'll supply the internal urethral sphincter it'll come over here and supply the internal anal sphincter and a supply the rectum it'll supply the sigmoid colon and the descending colon and then lastly it'll supply the last part that little distal one-third portion of the transverse colon now what are the effects there it's gonna be pretty much very simplistic it's not going to be hard if we come over here to the distal half of the transverse colon and the sigmoid colon what do you think it's gonna do it's gonna cause increase in motility so the overall effect here it's gotta be the same I'll write it down here just for the heck of it though it's gonna increase what the motility here so it's going to increase in these three points here the sigmoid colon the distal half of the transverse colon and the descending colon it's going to increase motility specifically through peristalsis and different types of segmentation and how strong contractions there's all different types of mechanisms here okay now next part it comes over here to the rectum and it can actually cause the explosive contractions there within the rectum to try to blow the poop out right but right here there's a piece of muscle right there's some smooth muscle right here around the anal canal and this smooth muscle right here is called the internal anal sphincter so what does this sucker here called it's called the internal anal sphincter now when you're in the parasympathetic mode you can go ahead and blast out a long one if you want to if you need to right because you're resting so what is it going to do it's gonna act here on the internal sphincter now if you're relaxed you're ready to go it can actually cause this guy to get stimulated if he stimulates what does he do so this will relax and if it relaxes remember this isn't the only thing you also have your somatic nervous system which innervates the external you know synced ER and if the somatic nervous system innervates the external anal sphincter and it's appropriate and you have conscious awareness that hey this is okay to drop a log here then you can go ahead and do it right but again it should have internal anal sphincter it will relax which will allow for the feces to move forward but again don't forget the somatic nervous system has voluntary control over the external anal sphincter which is skeletal muscle this one here is involuntary okay alright now next part they come over here to the bladder so the bladder again it's the resting the digesting the defecating the urinating phase right so what are you going to want to do here you're going to want to cause the actual bladder to contract so it's going to stimulate bladder contractions so it's going to try to stimulate the bladder contractions specifically by acting on the to trust our muscle and so it'll act on different types of receptors here like muscarinic like specifically type of three receptors and cause those suckers to contract what else it also can act on to the internal your wreath roles finked ur so here it'll act on this sucker here and this is called the internal urethral sphincter the internal urethral sphincter when the acetylcholine is actually released here it'll stimulate this guy what do you think he'll do he'll also relax so as a result here this guy will relax and help you to let the urine out so it's going to cause bladder contractions internal urethral sphincter relaxation again the somatic nervous system has control over another muscle right where the urogenital diaphragm is it's actually going to be called the external urethral sphincter so you do have voluntary control of when you think it's appropriate to pee but this guy will relax this win again and it's involuntary okay last part for the gonads so for the male reproductive system it's mainly remember parasympathetic point so what do you think it's going to be for and gorging the penis right so it's gonna help with erection all right so it's gonna cause it works through a mechanism generally parasympathetic nervous system doesn't affect your blood vessels directly it can do it indirectly it releases acetylcholine on to endothelial cells which can help to produce what's called nitric oxide nitric oxide can dilate blood vessels in the actual kippur a cavernosum the erectile tissue and dilate those blood vessels and increase the blood flow to engorge the actual penis with blood right to maintain the erection so for that purpose it's going to try to cause the erection now for the female it's the homologous tissue there's a structure called the clitoris right it's gonna increase the blood flow to the clitoris so what do you think is going to do there it's gonna cause clitoris engorgement so it's going to increase the actual blood flow to the clitoris and by doing that it's gonna affect the erectile tissue within the clearest yes they do have a rectal tissue also it'll actually dilate the blood vessels via nitric oxide release increase the blood flow to the clitoris which will help but they actually becoming more gold gorge right okay so we covered a lot of stuff here okay so again just remember the pelvic splanchnic tariffs are from s2 s3 s4 and I didn't mention here like I did all the other plexus but there is a plexus here that it goes to they call the hypogastric plexus if you want to remember that specifically the inferior hypogastric plexus okay alright so ninja Knights we covered so much information I hope you guys really did enjoy this video I hope you learned a lot I hope it made sense if you guys did like the video please hit the like button comment down the comments section please subscribe guys well once again we have an Instagram Facebook and a patreon account if you guys could donate to us even if it's just a dollar it would mean the difference in us being able to make the most high-quality videos for you guys alright engineers as always until next time [Music] you you

Channel: Ninja Nerd

Views: 191,769

Keywords: neurology, parasympathetic nervous system, parasympathetic

Id: F3U9pB5w0XM

Length: 36min 45sec (2205 seconds)

Published: Wed Dec 20 2017