so exam three exam three is uh in the rear view mirror tends to be one of the more challenging exams that in exam four which is coming up and the reason for is because of the content like muscle physiology and then nerve physiology that we're going to be covering in exam 4 those are the two most challenging um mechanistic processes this semester so three and four exams exam three and exam four tend to be the ones that are the most challenging uh the average uh total uh was 69% so it was down a little bit from where one and two were and um and I think four will probably be in the same range hopefully it'll be up a little bit but just historically that's kind of how those exams play out and then exam five the last one uh I think is probably one of the most straightforward exams special Senses um we have the least number of lectures it's really focused material yes there's review uh maybe a little bit more than a typical exam uh the the final or exam five is more like an exam five than the true final it's probably about 20 maybe 25% review and and then 75 to 80% new material focused on special census okay so if you're dropping your lowest and you go into the exam five or the final and you're like I got to do well on this one to kind of earn the grade that I'm looking for you're well situated exam five is not the the hardest exam of the semester does that make sense I'm reluctant to say it's the easiest because then people like oh my gosh you said it was the easiest it was hard right it like shoots you in the foot but it tends to be the most straightforward so we drop your lowest how that's going to work is you'll know exactly where you are going into the final and if you've performed solid all semester and exam five you don't need because you have the grade that you want without exam five then you can skip exam five only if that's going to be the lowest exam that you draw does that make sense so we're going to really want to double check and make sure that that is truly the case for you so there aren't any surprises so you saw probably the messages that I sent uh I sent one over the weekend saying now your exam three total score is inputed and your canvas overall score should be fairly accurate so we'll we'll do that again towards you know exam four and exam five we'll have a lot of practice before we get to exam five so you know exactly where you are any questions on how that works okay uh this week you actually have two quizzes due Friday quiz nine and quiz 11 so the peripheral nervous system quiz nine and quiz 11 is due Friday by 11:59 PM okay so don't forget I think it'd be great to go to SI sessions and review sessions this week if only for the purpose of reminding you what to do Friday evening okay that's not the only benefit but that's a huge assistance for you so we're in peripheral nerves the peripheral nervous system the pns today and Wednesday and then we're in ner physiology next week and then the week after that we'll finish out ner physiology in an online lecture you'll see that on the syllabus and then we actually have no class the Wednesday before the exam maybe we'll do a review session that because I'm gonna be out of town that week I'm in I'm out a uh soccer um uh tournament out out of state so that's been on the syllabus since the beginning of the semester because I knew that I was going with my daughter okay so then we'll schedule the exam when I get back so I'm here so that Wednesday before the exam we'll probably do some sort of extended review session in class for those that want to be here make sense all right why was six afraid of seven because seven eight n you guys have heard that one you have dads too that's amazing who earns a driving who earns a living driving people away who earns a living driving people away a taxi driver you could substitute it more you know waycom or uh Uber driver lift driver okay what has two holes no legs and runs two holes no legs and runs a nose well done very well done speaking of that what do you call the hair under a cow's nose a mustache very well done very well done all right I appreciate the class participation that is fantastic so the peripheral nervous system and then nerve physiology now if you remember I shared with you that was about a year and a half ago maybe two years ago uh there is this conservative effort to make some adjustments and the adjustments are what you're you're experiencing where we actually lectured on muscle physiology before we muscle we lecture on nerve physiology and the rationale is to be a little bit like more in sync with lab now historically I fought it because you can't actually get a muscle contraction unless you send an electrical signal to it so I and many of my colleagues have always taught nerve conduction first and then the muscle contraction um so many of your predecessors actually gave feedback back in formal questionnaires we actually read those like you're going to get a notification for student survey feedback I promise you it's Anonymous unless you're like hey it's uh Joe Anderson from your section one you know um if you do that obviously it's not Anonymous and some students do that right but if you need to give genuine feedback and you wan to be anonymous with it you can and that's what that platform is all about and so we take those in consider ation I mean some of them obviously you know students are like hey it'd be a way better class if there's no exams like yeah and then it's not called the class and then you can't get credit for it and it's not college but I hear you um but some but your your predecessor said hey I we would like to see a little bit more in sync with lab and so we made this conservative to move things around now I don't think it's perfect but I think it does help us line up a little bit more and so what we're getting into is we're going to move out of the central nervous system into the periphery as we move into the peripheral nervous system remember it's going to link back up to the CNS that we just left and then next week we're going to start nerve physiology which is out in the periphery see this is my you know attempt to try to make it look like it's nice and smooth and we intended it this way but it works right we're going to be out in the periphery and we're going to receive electric signals out into the periphery it's got to originate the central nervous system system to the peripheral nervous system out into the periphery so it can go to the working muscle or the muscle that's about to work that's where we're connecting all these dots now you know I've said this lots of times in this class the body doesn't really care that we're in chapter nine and chapter 11 that's what your quizzes are for Friday it doesn't think about it everything is connected but we have to segment these things out so that we can actually create content that's in bite-sized pieces so that we can study them and we can understand how everything links up and so this picture in the upper left these are autonomic neurons in the anic nervous system of the digestive tract and we'll see that so the digestive tract is littered with nervous tissue in fact it has both what we're going to refer to as sympathetic itic nervous system Innovation as well as parasympathetic nervous system Innovation and it has its own like internal nervous system known as the anic nervous system it can operate essentially on its own it has a motility that's generated on its own that's how important it is for the contractions of the smooth muscle in the GI track to actually move so that you don't actually have to think about moving the food through so you can absorb the nutrition so this peripheral nervous system if we look at a schematic of where we are this peripheral nervous system consists of sensory and motor and we saw a little bit of that in the last part of the last lecture and I'm going to refresh from there we're going to kind of take a half step back and then move forward we're see some familiar slides that we've already seen on sensory and motor and and that's intentional so that we can kind of move from the central nervous system to the periphery because again there is this harsh delineation that we make but the body doesn't see it that way right but the central nervous system I mean we like to be very organized like we want to have our label maker out and we say here's the brain and the spinal cord and that's the central nervous system and everything else is not part of the central nervous system and that's how we Define it so where do cranial nerves sit where do cranial nerves sit are they in the central nervous system or the peripheral nervous system what's that I heard both answers they're not in the central we talked about in the central but if you recall I said asri I'm introducing them here but they're not technically part of the central nervous system they're actually out in the periphery right but you look at them with the sheet brain on the underside right and you identify him underneath the sheet brain and so you kind of think as a student which is understandably so that the cranial nerves are part of the central nervous system but they're out in the periphery so that's a perfect example of kind of how it's sort of arbitrary where we draw these lines so we left this now we're moving over into here we're going to talk about sensory and motor that actually is divided further into visceral and somatic visceral another name for it is autonomic nervous system the a omic nervous system part of the visceral motor the autonomic nervous system is made up of sympathetic this is fight or flight and parasympathetic rest and digest things that ramp you up increase your heart rate increase your breathing get you ready for activity things that actually slow you down and get you ready to take a nap so is it more complicated in the central nervous system according to this slide you would think think so I don't think either one is more complicated than the other I think the more complex the biggest complexity is understanding that we kind of arbitrarily refer to this as the CNS and we arbitrarily refer to this as the pns but they are completely linked does that make sense so the autonomic nervous system what is the autonomic nervous system the ANS do also known as this visceral motor system from that prior slide this modulates a lot of homeostatic activity a lot of basic body functions you can see the list here like body temperature digestion heart rate metabolism breathing defecation urination that's pooping and peeing and then pupil diameter and hopefully you can appreciate all the different outflows of the sympathetic division on your left side and the parasympathetic division on the right the sympathetic being the ones that kind of ramp you up get you like enthusiastically ready for activity and the parasympathetic which kind of slows you down makes you tired in all of the organ systems in the middle here some of which have dual inovation and we'll talk about that on Wednesday they're inovated by both sympathetic as well as par parasympathetic so you can say for example the heart the heart has fibers that are of the sympathetic variety as well as fibers that are of the parasympathetic variety so it makes sense you get into a situation where you need to increase heart rate so you send sympathetic outflow sympathetic signal to the heart to speed it up there are other times you want it to slow down and rest because you want to go to sleep have you ever gone to sleep and you have a racing heart it's hard to fall asleep because you can hear your own heartbeat right you can you can feel it like in your eardrum or you know you just kind of feel your heartbeating you're like I wish it would slow down for crying out loud then that makes you more anxious and then it speeds up so the parasympathetic outflow is what slows down your heart rate what's interesting about the heart is the heart and you'll see this in 202 next semester the heart has an intrinsic pacemaker it's Auto rythmic and it beats at about 100 beats a minute so if you take a heart out of the body and you peruse it it'll actually beat at 100 beats a minute what do you think your resting heart rate is right now you could probably check it real quick what is it 70 80 well now that you asked 115 color what is it anybody in the 60s your neighbors asleep look at their watch and tell me if they're in the 50s okay so anything below 100 is going to be parasympathetic innervation of the heart slowing heart rate down then anything above a 100 is sympathetic activity stimulating the heart rate to go up so when you go from a resting state you're sleeping at night fire alarm goes off your heart rate immediately jumps in the next couple seconds the first thing that happens is the Paras sympathetic interation slows down the outflow from the parasympathetic side decreases and it immediately takes your heart rate from resting of 40s or 50s to 100 and then the sympathetic adrenaline epinephrine nor epinephrine takes it up from 100 to say 115 125 150 so that's how the organ of the heart works and it does it really quickly okay you've seen the slide before we've talked about the different parts of a reflex we've talked about the main characteristics four main characteristics who can remind us what those four main characteristics are four characteristics of a reflex stereotypical fast rapid involuntary it needs stimulation now we're connecting the central nervous system out into the periphery this was our link between last unit and this unit with the parts of a reflex and we went over the different sensory receptors we talked about the muscle spindle the afferent fiber the interneuron in the spinal cord the efferent neuron going to the muscle itself and we said that it's a sematic reflex which is skeletal muscle and we said that it's a visceral reflex if it's smooth or cardiac now this terminology of visceral should make sense right because we're talking about autonomic nervous system so one of your classmates was in my uh office before the exam kind of wrestling over visceral this terminology right and hopefully this kind of connects the dots a little bit that's autonomic where we sit today we also had a a question that looked like this that wasn't on the exam right but now that I'm showing it to you could it make its way on the next exam yeah it should it could sure could because it's in lecture now so it's game on so let's review this the Left Post Central dri receives information about the texture of a fabric you're touching with your hand along which spinal nerve did the signal enter the spinal cord on its way to the brain who wants to dissect this for us we already did it once in class let's do it again real fast any takers on last Wednesday you were ready for this I know you were a is it a it is a why is it a sensory information goes into the poster aspect the poster horn it it's it's on the the right side of the spinal cord and it's going to decussate at the level of which structure the medulla To the Left Post Central gyrus so it's on the right crossing over to the left perfect okay we talked about muscle spindles we talked about how they give you an indication and changes of what muscle length or tension length length we talked about the GGI tendon organ giving us information about changes in muscle what tension so these are reflexes that are in the central nervous system or are they out in the periphery they're out in the periphery and so last week on Monday a week ago we introduced some of the peripheral nervous system as we categorized it under reflexes because the central nervous system and the peripheral nervous system are both involved in reflexes right they both have a role because the spinal cord is part of the central nervous system but these organs the Gogi tendon and the muscle spindle are out in the periphery so where do you test on that you test on central nervous system or do you test on in the periphery do you see the conundrum we have but for sake in completeness now we kind of tell the story again and you can kind of see the link between the central nervous system spinal cord and the periphery where we're out with our reflexes okay so now what I want you to do is I want you to partner up you have to partner up so look at your partner and you have to look into their eyes yes you're like oh my gosh okay look into their eyes Okay I want you to look into their eyes you got to be close you two have to be closer that's you can't like gaze into each other's eyes from afar you have to be able to appreciate the size of their pupils okay the pupil is the dark part of the eye I know we're not at special Senses yet so way to make this brighter in here okay all right y'all ready look at each other's eyes okay can you see the can you see their pupils can you see their pupils don't be weird about it but like you know you got to get close enough you can see if your glasses are dirty you G have to wash them okay ready all right all right I'm gonna shut off the lights don't freak out I'm shutting off the lights okay shutting off the lights and I should probably dim this screen okay St you're gonna be staring at each other's eyes hang on Staring at you's eyes I know you're like I can't see their eyes you're gonna see their eyes oh now I can't see you're GNA see their eyes here shortly okay you remember where their eyes are right remember where their eyes are now I want you guys to find the pupil quickly and see what happens to it watch it ready wait for it uh which button is it there it [Laughter] is okay all right here's another variation it's more fun to turn off the lights pull out your phones turn on your flashlights don't like damage and blind your neighbor's eye but if you look get their permission you can kind of move the light in front of their eye and you'll watch the pupil change okay let's see it check it out it's the only time in class you're allowed to pull out your phones so for our future doctors right you guys do this in the exam room so what's happening what's happening what's happening somebody somebody describe what's taking place right now other than the light show how many you how many you have parents that like they walk around with the flashlight on in their back pocket yeah I know that's me my daughters like Dad Dad your your butt's glowing like all right so what's what's the purpose of this exercise what's happening with this pupil what what's it doing I mean it's not a complicated like I don't know if it's parison but don't worry about that is this the central nervous don't just tell me what's happening they're getting bigger they're getting smaller when do they get bigger when do they get smaller just use simple words oh did I thought you were raising your hand they're constricting and dilating okay when do they constrict when the light's bright it constricts that means it gets smaller to allow less lighting in they dilate they open up when do they open up when when it's dim or there's less light so this is a reflex because you're not like bright light bright light you know constrict constrict constrict you know you're not telling it what to do right here's another example of a reflex an easier example than last Monday with the muscle spindle and the goldi tendon I know you guys are studying that for the exam and you're like he didn't you know really ask much on there stay tuned right but this one this is another we have lots of reflexes and last week I just introduced two and we're we're going to talk about a couple more but the whole purpose of the reflex right stereotypical fast faster than Keller can even find the button Hit the lights right fast stereotypical um needs a stimulus like some activity right these are all character istics what was the fourth one that I'm missing oh involuntary yeah that's the easy one involuntary you're not thinking about it so with this pupil response it's trying to set up these different types of reflexes that are automatic or autonomic reflexes they're unconscious they're stereotype they're in some cases they might even be slower and they involve visle receptors or affector organs like the heart is the tissue of in in this next one this one's actually referred to as the Barrow receptor reflex and this Barrow receptor reflex is going to control the heart based upon the pressure that's being detected so I've got a little video for you reflex is one of the mechanisms the body uses to maintain stable blood pressure levels or homeostasis bar reflex is a rapid negative feedback loop in which an elevated blood pressure causes heart rate and hence blood pressure to decrease reversely a decrease in blood pressure leads to an increased heart rate returning blood pressure to normal levels The Reflex starts with specialized neurons called Barrow receptors these are stretch receptors located in the wall of the aortic Arch and kateed sinus increased blood pressure stretches the wall of the aorta and kateed arteries causing Barrow receptors to fire Action potentials at a higher than normal rate these increased activities are sent via the vus and glossal nerves to the nucleus of the tractus solitarius the NTS in the brain okay let me just pause it there as remember I told you when we see the cranial nerve NES I will Point them out right because when you're studying them in lab and you're just memorizing like okay Vegas nerve is cranial nerve 10 Keller is saying they're not part of the central nervous system they're out in the periphery well the Vagas nerve here is sending information from the heart back to the brain stem that controls cardiac centers we learned about that in the last unit right so this is a peripheral nerve we call it a cranial nerve but it actually is helping to manage heart rate as it relates to if your blood pressure is high or your blood pressure is low same with cranial nerve nine the GL glossal fenial nerve is how we refer to that this lady is a little robotic is the NTS activates the parasympathetic system the PSNS and inhibits the sympathetic system the SNS as the PSNS and SNS have opposing effects on blood pressures PSNS activation and SNS inhibition work together in the same direction to maximize blood pressure reduction parasympathetic stimulation decreases heart rate by releasing acetal choline which acts on the pacemaker cells of the SA node inhibition of the sympathetic division decreases heart rate stroke volume and at the same time causes vasod dilation of blood vess together these events rapidly bring down blood pressure levels back to normal when a person has a sudden drop in blood pressure for example when standing up the decreased blood pressure is sensed by barel receptors as a decrease in tension bar receptors fire at a lower than normal rate and the information is again transmitted to the MTS the MTS reacts by inhibiting parasympathetic and activating sympathetic activities the sympathetic system releases norepinephrine which acts on the sa Noe to increase heart rate on cardiac myocytes to increase stroke volume and on smooth muscle cells of blood vessels to cause Vaso constriction together these events rapidly bring up blood pressure levels back to normal bar reflex is a short-term response to sudden changes of blood pressure resulting from everyday activities and emotional states if hypertension or hypotension persists for a long period of time the bar receptors will reset to the new normal levels in hypertensive patients for example bar reflex mechanism is adjusted to a higher normal pressure and therefore maintains hypertension rather than suppresses it okay so let's talk through a little of this but I think that does a nice job of explaining a totally unique reflex a little bit more complicated than a pupil dilation or constriction reflex a little bit more complicated than last week and today's muscle spindle and Goldy tendon that are measuring length and tension respectively um but critical right so throughout your day your blood pressure is going to change and and don't think of blood pressure changing as being like Oh like old people that have health problems just throughout your day you get up in the morning you wake up and you get out of bed your blood pressure changes okay you have a meal you sit down you go to lecture your blood pressure changes you get ready to go work out in the afternoon your blood pressure is going to change and so these reflexes are important for giving you this Dynamic capability to manage your blood pressure throughout the day and you see this probably you've seen this even in young people that they run into problems where they stand up too fast and their blood pressure crashes and they faint right maybe you have friends that are in this this category there's this vasovagal Syncopy is they stand up too quickly they get up from bed or from a sitting position too fast and all the blood rushes down from their you know ahead and they get dizzy and they they pass out and the reason for that is because this reflex isn't happening quick enough right if you get up from a standing from a sitting position real quickly you should adjust and increase your blood pressure in the next couple of heartbeats so that you're able to accommodate the change in activity so these reflexes are really critical for everyday activity everyday life um we've got a couple of things labeled here that I want to walk through so we can see here that in the in the lecture video as well as here on this slide these Barrow receptors that are found in the kateed artery are like door sensors like your car has a very simple sensor to let you know when your doors open even even if you have a very basic car right there's a dome light in your very basic car that has a setting that if a door's open the light's on you guys know what I'm talking about you can turn it to off or you can turn it on and sometimes if you turn it on and you think it's to the door setting you close your door and you look in and you you don't pay attention your battery could be dead the next morning right so that door sensor light is like what's happening here but this isn't this isn't detecting what the door is closed or open it's detecting the the pressure which is very very similar to what I just described and so when there's an increase in blood pressure in the kateed artery The receptors see that and send it via cranial nerve nine and and 10 this one's showing just the glossal fenial but it's also um the Vegas that goes to the brain stem and then there's an neuron that sends the the uh outflow via inhibitory neurons down the vegus nerve cranial nerve 10 to the heart and this terminal gangon is a cluster of nerve cell fibers and innervates onto the heart to lower heart rate and so this feedback loop has all the same kind of components that we looked at last week now I want to watch um I want to show you um a uh mition reflex so this is the reflex that's associated with urination or peeing tuition reflex when the bladder is full stretch receptors in the wall of theion this part of the reflex is involuntary and is predominant in infants and young children as the central nervous system URS it requires voluntary control over the external ureal spin urination is controlled mainly by the MCU Center in the P this Center receives sensory signals from the bladder and communicates with the cortex about the appropriateness of urinating at the moment at times when it's not convenient to urinate the center sends back an invatory signal the fing is close and prevent voiding when you wish to urinate this inhibition is removed the spinal cord instructs the musle of the bladder to contract and the to open to let the urine out okay another example of seemingly a more complicated reflex but really really important right and so you saw there's two components here we've got an involuntary component that's the reflex and then we have voluntary control over the external sphincter that we can train and that's potty training right so what happens in geriatric populations when you know your par your uh patients parents too right eventually your patients lose the ability to control voiding and a lot of geriatric patients are wearing diapers right depends because they have lack of control over urination so what's happening in those circumstances well that feedback loop that's a sensor feeling the stretch of the bladder which is Transitional epithelium so it can give a little bit and accommodate but it's some point you know that urge to pee you know what I'm talking about it's pretty strong and you're like I got to find a bathroom fast right it gets very uncomfortable and that signal goes up to the brains in the sensory cortex and is giving you that feedback and it's sending it to the motor cortex and you're saying not right now okay and that's your frontal cortex conscious thought overriding this reflex and so that sends an inhibitory signal down to the external sphincter to contract and say no right and it closes down and that along with you know fancy dancing or crossing of the legs keeps you from peeing all over yourself well as you get older muscle control becomes a little bit less tenable right muscles atrophy they become come a little weaker they're not as responsive you see that in elderly patients with skeletal muscle you see it with cardiac muscle because they have cardiac problems it happens with these sphincter muscle controls as well and so they may have to go to the bathroom more frequently because they know I can't hold it as long as I used to and then at some point there's really no more control over that okay that's all reflex that's connecting our central nervous system to our pereral nervous system so already we've talked about five different reflexes in in pretty great detail muscle spindle gy tendon pupil dilation barer receptor and mition reflex and reflexes are the best way for me to connect the central nervous system to the peripheral nervous system does that make sense give me trying to give you tangible examples of what's going on okay so let's talk about these visions of the autonomic nervous system the autonomic nervous system parasympathetic and sympathetic so I said earlier that the sympathetic nervous system is the fight ORF flight response that's like physical activities that's going to increase your heart rate that's going to increase blood pressure increase breathing increase blood glucose availability yeah that's a lot to fit in that line I get that it's going to increase skeletal muscle profusion all of these activities of increasing get you ready for activity heart rate goes up breathing goes up um blood pressure goes up perfusion of the muscles glucose sugar availability in the bloodstream why does sugar availability in the bloodstream go up what's the purpose of that if you're getting ready to exercise what's that ATP thank you via what mechanism glycolysis absolutely fast energy right really quick and it's going to decrease blood profusion to the skin and blood profusion to the digestive tract so you have a limited amount of blood and the average individual you have about five to six liters of blood and so if you're getting ready to exercise you want to shunt that blood away from areas that really don't need it at that moment in time it's not the time to digest a meal and sit down so you shunt it away from the GI tract so you decrease profusion to the GI tract or the digestive tract and you decrease profusion to the skin because the skin takes a lot of blood flow it's the largest organ in the body now once the activity is happening and you become hot and you need to Thermo regulate you may start shunting some blood to the skin so that you can start sweating but that comes later the parasympathetic nervous system and we usually abbreviate this PSNS sometimes you'll see it as pns but the confusion between pns referring to parasympathetic is some students see it as peripheral nervous system so my favorite is to say uh parasympathetic nervous system PSNS but you just need to look for contextual Clues because sometimes I forget okay and some textbooks do forget as well so the PSNS is the parasympathetic nervous system the SNS is the sympathetic nervous system and the PSNS or the sympathetic nervous system is rest and digest or feed or breed calming activities so this is going to reduce energy expenditures you're going to supervise is an interesting word but it supervises or oversees digestion and waste elimination and so waste elimination you saw maturation reflex right you actually have to relax the muscles in order to pee so that's a calming activity of relaxing to actually eliminate urine it's the same thing with defecation is you actually have to relax the sphincter muscles not contract them in now in order to defecate or to poo okay and so there is a clinical situation that happens a lot in elderly patients unfortunately have heart problems and um sometimes in in in medical uh er um response it's called commode mode where or mode commode where a patient actually has a heart attack on the toilet because they're trying to poo okay they're trying to defecate and they're trying to relax and expel go to the bathroom and it LO it crashes their heart rate and they pass out that's why in a lot of retirement homes if you go ever go visit and you see Grandma or Grandpa and you go use the restroom like why is there like a chain or a button right next to the toilet paper that's conveniently placed in case they're having heart problems because that's a very common location for that to take place because supervising waste elimination and digestion are things that slow down the system including the heart make sense often both of these things are active in some simultaneous fashion like we said with the heart like the example I gave with the heart where you've got sympathetic and parasympathetic ination and both of them can control the heart in circumstances where both are active we call it autonomic tone where the organ or the target tissue actually has some basil amount of electrical stimulation from both the parasympathetic as well as the sympathetic nervous system autonomic tone so the sympathetic nervous systems we refer to this as the thoral lumbar division thoral lumbar because the nerves are generated out of the thoracic and the lumbar spine thoral Lumbar and so you can kind of appreciate on this slide um the nerves coming out of the sympathetic nervous system occupy the thoracic region as well as the lumbar region we don't see anything out of the cervical region in green and much of it innervates glands glands specifically like the Adrenal medulla that sits right above the kidney the Adrenal medulla that sits right above the kidney located right here this gland is a modified sympathetic ganglion and and a ganglion is basically just a mass or a collection of nerve cell bodies and so the kidneys obviously have nothing to do with the Adrenal medulla or the adrenal gland just location because the kidneys filter urine and the adrenal gland specifically the Adrenal medulla has nothing to do with urine but has everything to do with manufacturing and secreting epinephrine and norepinephrine epinephrine is referred to as adrenaline and norepinephrine is referred to as noradrenaline so when you have a rush of adrenaline right you've heard this man I got like a rush of adrenaline and I'm ready just to go I'm all wound up well what's happening is your sympathetic nervous system specifically the Adrenal medulla is secreting copious amounts of epinephrine which is a sympathetic nervous system uh sympathetic nervous system stimulant and what does it do what does it do tell me what it does if it ramps up the sympathetic nervous system adrenaline increases your heart rate that's the first thing that comes to mind right what else is on the list increases respirations what else blood pressure secre of sweat if the activity is happening I would agree not right away but if the activity starts happening yeah okay does that kind of put put things in perspective that it's starting to kind of come together so this is a schematic diagram of the adrenal gland the Adrenal medulla is the middle portion the adrenal cortex is the outer portion the Adrenal medulla actually manufactures epinephrine and norepinephrine into the circulation and it's the spinal cord that's actually telling the a sympathetic preganglionic neuron manufacture this get it into the bloodstream and so let's use that middle of the night smoke alarm fire alarm or maybe it's the 6: a.m. Apple alarm telling you it's time to wake up and and you're not one of those people that you know and it's not one of those like like accelerating or or gently increasing with the lights you know those that are really sensitive help you to sensitively wake up right it's just like you know those kind that you hate but they work you hear it you pop up you count to like 101 100002 and you can then you feel your heart just like pounding because that's the amount of time that it takes for that adrenaline that epinephrine to get into the circulation and make its way around to your heart that's why there's a few second delay okay parasympathetic nervous system I I took the time to modify the slide yours probably just say pns I I said you know PSNS for the prior little notation so that you don't get confused this one is cranial sacral so if you can appreciate it's going to come out of the cranial outflow and the satral region now the obvious question is okay well why is the sympathetic nervous system out of the thoral lumbar and the parasympathetic out of the cranial sacral why are the nerves organized that way Dr Keller I have no idea that's the simple answer a theory is for thoral lumbar it makes sense because the Adrenal medulla is actually in the abdomen so it kind of needs to be sort of the lower part of like T8 or n maybe all the way to L1 or two that makes sense but for the rest I I don't really have a great answer for you but but what I do know and this could be part of the answer is this cranial sacral most of these are these cranial nerves that you're studying in lab and so you can see all these cranial nerves that are labeled here as they outflow out of the underside of the brain part of the peripheral nervous system and you're still not there yet I was just looking in lab at the I think it's next week you'll be in brain and brain cranial nerves so you're going to be studying this next week in lab so we're we're kind of approximating the flow of lab we're a little bit ahead still but you can hopefully appreciate um you know here's the ocular motor nerve this one goes to the eye the facial nerve the the glossal fenial nerve cranial nerve nine this goes to a lot of the salivary glands like prior to a meal right so prior to a meal it goes without fail like in my house our little Portuguese water dog she's very food motivated she eats six 12 and six okay she's very very static and about 5:45 she wakes me up because it takes me about 15 minutes to wake up and get a coffee and be in front of the pantry where she's sitting there drooling literally drooling so I open the pantry and I have a little like towel and I with my slipper I go like this and and and I'm pretty good at it I hold my coffee I'm halfway away I just do this and it goes right underneath her muzzle because her glossal fenial nerve is on 120% and she's just drooling waiting for that scoop of food it's unbelievable you can see we finished this out Vegas nerve which is cranial nerve 10 look at all of the sites that the Vegas nerve interat not just the heart that we looked at but the lungs actually inates um uh the abdomen areas like all of this from the Celiac ganglion into uh the liver and the gut uh the stomach as well as the gut the the Vagas nerve is probably one of the more complicated and the most sophisticated nerves of the cranial nerves cranial nerve 10 so the best answer I can tell you is because it's cranial sacral parasympathetic a lot of the outflow out of the brain and maybe because food and digestion is so critical for our activity and is dominated by the parasympathetic nervous system coming out of the brain right away is probably some evolutionary significance right we wouldn't survive if we didn't have really good methods to make sure sure that we have a meal right if my dog can't wake up Dad on time every morning she may not make it okay the anic nervous system and I kind of hinted at this earlier we'll finish out kind of the remaining time of this lecture talking a little bit about the anic nervous system um and then how these nerves kind of inter ate and then how they're organized and that's where we're going to finish today but the anic nervous system has both sympathetic as well as parasympathetic nervous system I think in your older version that you probably downloaded it says pns but I updated it with PSNS so maybe you make that notation and the parasympathetic nervous system and the sympathetic nervous system that inates the anic nervous system you can kind of appreciate um so this is the diaphragm that's right up here and this is the esophageal Hiatus uh this is actually the extending of the esophagus and this is the theme as it turns into the stomach makes its way into the small intestine into the large intestine that enteric nervous system which is made up of this myeric plexus and this submucosal plexus is contiguous throughout the GI track until it leaves the body right and the duties of it are to regulate motility and secretion your the purpose is to regulate how it moves via pistolic motion so that motion is you squeeze here you squeeze here you squeeze here you squeeze here and it moves the food that way right like squeezing a tube of toothpaste so you squeeze here you squeeze here now you don't want to squeeze too quickly because you don't want to move the food through the GI tract too fast you move it too fast you don't absorb enough nutrition and if you move it too fast which is a protective mechanism you eliminate what's in there very very quickly if there's something that's irritating the GI tra and then you have diarrhea if you move it too slowly you absorb too much of the fluid you leave behind too much of the waste that's solid and becomes a little bit more complicated to eliminate and that's constipation so it's really important for it to move at just the right interval and again tying it back to geriatric medicine what is the number one medical issue that the elderly go to the doctor for do you think it's cardiac do you think it's respiratory do you think it's cancer it's gut problems it's this it's the number one problem for the elderly is something is not going on correctly in their GI system believe it or not okay really really important so this plexus of the anic nervous system directly controls the GI track there's a plexus of about a 100 million neurons in the wall of the digestive system so this enteric nervous system is also considered kind of its own unique system all right so now I want to kind of finish out this little segment as we move on and I want to talk about um the anatomy or the architecture or the structure of the sympathetic nervous system and it's actually quite simple there's really only three main pre synaptic Pathways so what's a synapse what's a synapse when I say a pre synaptic pathway what am I talking about you remember the neuromuscular Junction so use that prior history and help me Define what is a synapse as it relates here to a pre synaptic pathway we've got three we've got a spinal nerve a a sympathetic nerve and a spanic nerve and they're circled for you so you can see from the central nervous system the spinal nerve outflow right here circled this spinal nerve outflow number one goes to sweat glands pector muscles blood vessels skin and skeletal muscles see number two the sympathetic nervous system goes up sympathetic nerve sympathetic nerve excuse me goes to Iris salivary glands lungs heart thoracic uh blood vessels and the esophagus and then the last one is the splenic nerve which basically goes to the abdomen right liver spleen adrenal gland stomach intestines kidneys urinary bladder reproductive organs so three Pathways that disseminate a widespread effect so what is a synapse back to the original question the point where a nerve fiber meets either another nerve or a muscle or some Target organ absolutely where the nerve fiber meets or inates to another nerve to another or to a muscle or to some affector organ that's all the synapse is and this is how we disperse this widespread effect via these three main pre synaptic Pathways now the anatomy or the architecture of the parasympathetic nervous system is a little different there's long PR synaptic axons they travel to a terminal ganglia right so for example in contrast here these tracks come out and they go through these three main routes or pathways here you have lots of different Pathways like cranial nerves and they go to these little ganglions you see these like celc ganglions the one that I talked about with the Vegas ner so these are like relay centers that are located out in the periphery slightly different organization now why is that significant because as we finish out today and we're going to end a little early but as we finish out today we we've got a somatic eer intervation and we've got an autonomic eer intervation and so I want you to be able to see these two different Pathways and we've got synapses so here's a synapse here it meets the definition that was just defined by one of your colleagues we had a nerve fiber that's coming out and instead of going onto another nerve it's going on to a skeletal muscle but there's still a synapse here fact this one's very much like identical like the neuromuscular Junction that we looked at previously here's the nerve and here's the muscle and look there's acetylcholine that was the neurotransmitter that we learned about already so this is the architecture of a somatic eer inovation somatic meaning like body like skeletal muscle now we're in autonomic autonomic eperen ination now autonomic this isn't a skeletal muscle because skeletal muscle is under somatic control autonom autonomic is under involuntary control like the heart so now we have two synapses right and I'm kind of doing this work for you instead of you with your partner on this one but I'll point out a couple of the things here in a second that I want you to talk about so share with me some of the differences that you see with autonomic we've got two synapses what are some other unique observations that you make voluntary up top involuntary down low has norepinephrine where the second one right so it's acetylcholine on the first one and then it could be acetylcholine or it could be norepinephrine on the second one now why would we use different neurotransmitters what's the point there why would you change the neurotransmitter availability okay that's a good guess stronger relay okay maybe one's more effective than another anything else these are good guesses speed speed okay another good guess for different functions is my favorite answer for different functions so you have more options available if you use different neurotransmitters now you have to have different receptors but this is really to give you this or gives you choices right this is you could go right or you could go left to your destination right this you put in the address and then you get like three different Roots do you want the fastest right do you want the the short distance do you want the least stops or right you know how these algorithms work the body operates in a very similar way okay so comparing and contrasting sematic versus anomic this is in a schematic this is in a table some of you are visual some of you are categorical this is the same information that we just saw previously on the previous slide so look at the feature the affector organ the target that's what that word means somatic is skeletal muscle that's this one right here and autonomic are glands smooth muscle or cardiac muscle like we saw in this example all three of those are involuntary or autonomic you look at the control just like I said voluntary under sematic usually involuntary under autonomic eer pathway one nerve fiber from the CNS to the effect organ no ganglia this is a ganglia that is the ganglia that we keep talking about when we say these different ganglion over here we have two nerve fibers from the CNS to the effective organ and there's a synapse at a gangon right in the middle like a relay Center the neurotransmitter on somatic is only a acetylcholine here it utilizes acetylcholine as well as norepinephrine the effect on the target cell with somatic is always excitatory anomic it could be excitatory or it could be inhibitory there is your option right you could have it be excitatory or it could be inhibitory because you have different neurotransmitters that you can use if you cut the nerve or if the nerve becomes damaged or there's trauma associated with the nerve what's the result denervation somatic you have flaccid paralysis we learned about that term in the last unit meaning flaccid paralysis you de innervate you are stuck in a relaxed State paralyzed unable to contract that's flaccid paralysis you dein on the autonomic side you have hyper sensitivity the Target tissue becomes hypers sensitive to the next response or the next signal so here's what I want you to do in the next couple of minutes and then we're done I just want to I just want to hear the chatter when you turn to your partner the one that you were gazing into their eyes just a moment ago I'm sure there was a connection because the lights were out okay I want you to define a sematic reflex arc on partner a and identify its major parts partner B I want you to define a visceral reflex arc autonomic and identify its major parts you understand what the what the task is so you're basically explaining this material to each other okay all right you're like uh yeah we understand okay so what do we do okay practice right now before you leave so that it sinks in right see1 do one teach one right spe everybody feeling pretty good about that okay so the last thing that I want to share with you and then I'll let you all go g leave a little early so unit three and unit four tend to be the most challenging material and next lecture I really want you you to read you have two quizzes 9 and 11 and I want you to at the minimum look at the lecture slides because there's often lots of questions about these different Pathways that we're going to talk about on Wednesday there's there's often a lot of confusion about these different Pathways that we talk about in the next lecture it's a great time if some of this is not setting in for you to get over to T a review sessions SI sessions ASAP so you don't fall behind because we're only in peripheral nervous system this week and then we move directly into nerve physiology which is a whole another category of of challenging information um with different types of minutia that you have to understand all right so now's our time to kind of be alert you guys okay with that all right well have a great evening I'll see you on Wednesday please look ahead at the material