hey everyone welcome to Professor Lawrence lectures in anatomy and physiology as you guys know I'm professor long-wear this kovin shut down and I'm converting my face-to-face courses to online so these videos are done quickly they're done crudely they're usually done in one take actually this one's on about takes six or seven because I'm dealing with two major emergencies that have interrupted me in the middle of these lectures where I've had to start over it's getting rather frustrating but I just got a lot going on but I'm no different I know y'all got a million things going on too so these videos are intended for those of you taking my anatomy classes at Del Mar College this video in particulars for my human anatomy and physiology one course I'm hoping this is the last lecture if not it'll be the next to the last lecture and we're done for the semester as you guys you know if you're not in my class well then I hope you learned something from it if anyone has some constructive criticism please provide it sometimes I get thrown off and distracted so these videos aren't as smooth as I'd like them to be there's certainly not the quality of production and slickness that I would like to have but I and I got kids and dogs and and things going on that are interrupting I'm dealing with some emergencies so occasionally I get a text and I have to look down at my phone and I'm trying to keep this rolling it's distracting so anyway if you're in my part one class where we're in the nervous system we did a whole series of quizzes on how neurons function how action potentials work and synaptic activity you've got to know that you must know action potentials sodium and potassium and the release of neurotransmitter and its breakdown and binding to postsynaptic membranes that is a huge concept in Physiology that's going to help y'all in the long term for your health careers and as students in in biology now once we got past that we started talking about the brain structures we went over the basic functions I mean a very fundamental understanding of which parts of the brain do some basic functions it's far more complex than I led you to believe and then we've gone into the spinal cord we went over the well the the first series of lectures the first lecture in this series for lecture test 6 or the series of quizzes that will be lecture test 6 was over the Ventura goals and cerebral spinal fluid and the meninges and then we went into the anatomy of the spinal cord and then we went into the physiology of what's happening inside the spinal cord now we are going to do chapter 15 and 16 these are two very big chapters especially 15 that are very complex and I want you guys to know something sort of undoes another disclaimer I have my I graduated with honors and biology a lot of my research was a lot of my work and my studies were in cell and molecular biology I also worked in a research lab as an undergraduate and got my name on some abstracts and did some presentations at some national and neuroscience meetings and things and my research was in neuroscience and neuro anatomy and physiology of the hippocampus or memory and learning occurs and then my Master's I went on I did a whole bunch of biochemistry in the brain some protein biochemistry but in neurobiology so my Master's is a neuro and then I did a I started the ph.d program and went through different neuro labs I finally wound up in a guys lab where we did a bunch of neurobiology really of the eye but it was all neuro I have a very strong understanding of the nervous system I know that there's three great frontiers left in research that are largely unexplored some people might argue there's a few others but the deepest space we know very little about we're just now touching that the deepest parts of the ocean were just getting to that in the past ten years and the deepest parts of the nervous system and how it really functions as a whole we know a lot but the more questions over the more answers we come up with the more questions it has the brain is extremely complex and there's no way in a single physiology or two physiology or two semesters of physiology and Anatomy that I can you know give you any comprehension know how this works so we're keeping it very simple and basic and fundamental also as my other disclaimer is a lot of my students are health science majors so I could go into all this complex biology and rattle off you know a hundred different powerpoints of all this stuff but how much are they really going to learn so I want my students a fundamental understanding of the brain and the spinal cord and what the structures doing and we're going to do some integration in chapter 15 and then we're gonna reiterate the sympathetic parasympathetic the autonomic nervous system in chapter 16 which we really have already done but we're going to touch on it again and test on it some more since it's so vital to your career so now that I've rambled for five minutes chapter 15 is integration the term integration and to integrate means to take other bits of pieces of things and put them together into a bigger picture okay so neural integration means we're taking all this sensory input sight sound smell taste touch vibration temperature pain we're taking all of this information feeding it into our brain and our brain has to make decisions to increase our chances to survive as an individual and as a species ultimately all organisms are designed to do two things are all animals anyway survive as an individual that means look around the world find food and water and resources for survival for constant consuming energy and avoid predators avoid becoming food for another organism so while we're eating and looking for food we have to be wary of predators if you watch the TV shows alone or naked and afraid or these survival type shows and I'm not talking about the TV show survivor that gets an associate on directions in psychology but I'm talking about physical survival when you're in the middle of nowhere what do you got to do to survive the second major function of survival is the species so once we've taken care of food and shelter and that survival the ability to avoid predators then we can worry about our DNA existing in the universe long after we die and that's what survival as a species is about find a mate make as many miniature versions of you that have your genetic information in it and hopefully when you're dead and gone your DNA will be surviving for generations and generations and generations and an incredible amount of our physiology and our sociology our social behaviors would be your psychology and all of this stuff you know really goes around those two things finding food and avoid becoming food finding mates and reproducing we really are machines for jeans and we are driven genetically biochemically to continue our survival into the future even after we're dead and gone that's why reproduction is such a strong drive and invokes so much emotion and energy now while we're integrating while we're taking information in we are really at the most fundamental levels thinking does this situation increases my chances of survival as an individual or as a species if the answer is yes you don't change it the answer is no you better have some kind of change in your interaction in the environment and so integration is helping us both take in sensory information and make sense of it but also to make decisions and send motor commands out the spinal cord to our effectors to adjust our ability to survive so that's all that integration is about taking small pieces of the puzzle figuring out what's going on and sending out the possible the proper proper motor commands there's a few definitions we have to go one of these definitions is a stimulus now we did this at the beginning of part 1 EMP but I'm going to repeat it and I'm going to take another look at it a stimulus originally is defined as any detectable change and the environment and that can be the internal or the external environment so if a car backfires in Houston Texas and I'm sitting down here in Corpus Christi I'm not going to hear it it's not a stimulus to me so some other organisms it might be but to me no the second one is going to if a thunderstorm is happening you know a few miles away and thunder goes off I'm going to hear that that's a detectable change that's a stimulus now in the world of neuroscience what that can also mean is this and this is going to lead us to this idea of integration when we take a sensation into the nervous system and up to our brain there's usually a series of three yawns and I'm talking about a lot of our somatic sensations for right now but usually there's a series of three neurons that go from the periphery into our spinal cord up to our brain and then to our conscious awareness not all of them work this way but I'm going to do these for my class from now and then later on you guys can figure out other details as you move on in your education so let's say I have something like touching my finger I have a sensory neuron out of the periphery that's going to extend to the spinal cord and as you guys know when we study the spinal cord I'm only going to draw half of the spinal cord here we have the dorsal root ganglia on our spinal nerve we have all this information okay so we're feeding information into the CNS at the spinal cord and then we have our gray horns a sensory neuron is going to come in through the dorsal root and synapse in the posterior gray horn and there's so much of the dorsal root ganglia okay so now I'm going to erase this in a second but ultimately the neuron coming in from the periphery into the posterior a gray one it's called the first ordered neuron because it was the first one in a series of three now that neuron is going to synapse on another neuron here in the posterior great horn that's going to send an axon out through one of the white columns up to our brain so we have a second neuron that's going to go up and usually not always and we're gonna learn the exceptions of a couple of minor exceptions in a minute but usually it's gonna go from the spinal cord up to the thalamus or wherever it goes up to which part of the brain it goes up to it's gonna be called these second order neuron because it's the second one in the in the series of three now the third order neuron usually is going to go from somewhere in the brain some higher center from this one we're going to use the thalamus and it's going to go to the post central gyrus if you remember we had the tree and the post central gyrus with the central sulcus the post central gyrus was the primary sensory cortex and some sensation in the body is going to be somewhere along the coast central gyrus that neuron that extends from the thalamus to the postcentral gyrus is going to be called the third order neuron so if you're following in my note set then we're on page 91 we have the definitions up here we talked a little bit about integration we have the definition of a stimulus we're going to add sensation and we're going to add a third one that's not there called perception in a moment but if you get to the bottom part of the page it tells you all sensory pathways or many of them pass over a series of three neurons from the periphery to our cerebral cortex they're called the first order neuron the first order neuron extends from the periphery to the posterior gray horn and synapse are at soma lies in the dorsal root ganglion so you need to know that information that's what's in bold in my notes set that's what I want you to know the second-order neuron you need to know where the soma lies it lies in the posterior great horn and it will send its axon through an a sending tract of the spinal cord usually to some higher center right now we're talking about the thalamus so you need to know that about the second order neuron the third order neuron starts in some nucleus or since or high up in the brain right now we're talking from the thalamus and it will usually extend to the cerebral cortex in some way or form so you need to know all of that information it's let's embolden the note set it'll be in the worksheet for you to fill in and what I want you to know is because our brain is taking in sensory information and making sense of it all sensory tracts that enter the spinal cord have to go up the spinal cord to higher centers so anytime you hear the term a sending tract you should automatically think a sending tract equals sensory tract all sensations are going to come into the spinal cord the tracks and the spinal cord will go up the white columns one of these white columns here and in these areas we have little bundles of axons and you know in three dimensions they would be traveling up and down the spinal cord a little Reed all this prettier in a moment oh that's why we call them traps than bundles of axons and if I have information coming in from a particular region of the spinal cord they're all going to share the same tract now when we're talking about a stimulus and we're talking about this set up all they sending tracts are sensory now what I want to get to is a cup of things okay let me erase this and we're going to talk about this in a little bit more detail but before I do so imagine this if you guys were sitting in a room and I have someone else in a second room and I have you staring at a monitor and that monitor is showing us an action potential for this first-order neuron and it's sitting here at resting membrane potential minus 70 millivolts okay you can tell me if this person detected a stimulus if I'm sticking electrodes in here and running it into a box and reading the voltages like we do in an action potential and you see this if the resting membrane potential is never disturbed and that that neuron then you know they haven't received a stimulus okay now this is where the general senses the special senses we have to monitor a different cell call to receptor cell we'll get to that later part two now if while you're reading this you see these little positive EPS piece or iPS piece you know something has caused the cell to open sodium or potassium channels that's a stimulus if it fires an action potential then that changes from a stimulus into what we call a sensation but for now a stimulus is anything that alters the resting membrane potential of your receptor cell or first order neuron so anything that alters the resting membrane potential of this first neuron at least in the general senses is going to be called the stimulus okay now if it does reach threshold and fire an action potential we know that neurons can release a ton of neurotransmitter at this synapse if someone else is monitoring this neuron and you see changes in interesting potential or it fires an action potential that's what we get to which call the sensation now in one sense a sensation is any stimulus that is processed by this CNS well if this neuron never reaches threshold the first order neuron we're never going to have it reach here it would be shut down before it gets there once this neuron fires an action potential we will actually turn this into a sensation another way to define a sensation is any stimulus strong enough to alter the resting membrane potential of the second order neuron any stimulus strong enough to alter the resting membrane potential of the second order neuron anything that disturbs that we call the sensation now not all sensations reach our conscious awareness many times this sensation will fire but somehow someway our thalamus has the ability to filter out a lot of sensations over 99% of them because we can only pay attention to what's important for example while I'm talking to you and waving my hands you guys are very much unaware that there's a little ledge right here or there's a metal border around this or that I'm holding markers in my hand over here because you're trying to pay attention to what's important and your brain has to filter out the seat pressing on your butt your clothes on your body get all filtered out so that we can pay attention to important information if the third-order neuron fires an action potential and we become consciously aware then that's the definition of perception perception is the conscious awareness of a sensation if we're not aware of it it has to reach to our perception so perception is the conscious awareness of the sensation at least for now so the three definitions you need to know and on two of them you need to know two variations the stimulus is any detectable change in the environment or anything that alters the resting membrane potential of the first order neuron a sensation is any stimulus that reaches the CNS or any thing that alters the resting membrane potential of the second order neuron perception is the conscious awareness of the sensation now when it comes to our sensory pathways all sensory pathways are a sending we don't have any structures up here that interpret sensory information and an integrative way and so in order for information to be processed by my brain I have to send it up the spinal cord into my brain or into a cranial nerve higher up so whenever I talk about and we said this a second ago an a sending tract the word a sending tract and immediately trigger you to think oh this is sensory because the sensations have to go up the spinal cord and if we do look at the spinal cord in cross-section there's a bigger version of it you guys kind of know this Anatomy now from the previous lectures these white collars are actually divided up and let me redraw this one this one has two little funky bumps in it called fascicles the one that's closer to the posterior median sulcus here is called the fasciculus gracilis okay and then the one that comes after that or next to it I should say is called the fasciculus cuneus all right so the fasciculus gracilis and the fasciculus Kuni artists these two fascicles player or these two structures have a lot of sensory tracts in them so this next month next to this is called the fasciculus Kuni honest okay on the opposite side of the spinal cord I'd have the fasciculus bacillus in the fasciculus Kuni honest near the outer edges of the posterior white column when we look at all of these areas of the spinal cord there are little round structures in here that if stained them and dyed them we would see these little round structures in here and inside of them these little dots would be excellence coming up the spinal cord and if we looked at the spinal cord in three dimensions and we would have this tract would look like a long tall column that's why we call these white areas of the spinal cord white columns and essentially each white column has tracts running up and down the school cord and within those tracks our axons that share common origins and destinations for example I'm gonna erase this right here I'm going to try to give you an example of what I mean so that all of this will make sense if I have a bunch of sensations coming in from my finger they're all going to synapse in a certain level of the spinal cord and then all these axons coming from here and going up are going to be bundled together and they might be found let's say in this particular tract so I would have a bunch of axons coming up from some level of the spinal cord going up through a particular tract to my brain if I have another level of the spinal cord where other sensory information is coming in it may ascend and I might find all those axons running through a totally different track in a different light maybe even on the other side of the spinal cord so we call the white areas white columns because within those white columns there are tracts bundles of axons with common origins and destinations in our nervous system what that means is if I compress a certain part of the spinal cord I may disrupt incoming sensory information or maybe outcoming motor information right now we're worried about the sensory traps so now all sensory pathways are going to travel over a series of three neurons first order leads to the spinal cord second order from the spinal cord up to the brain third order from some area of the brain up to the cortex all sensory tracks are a sending and I'm going to skip a page for a moment and we're going to skip over to page 93 when we look at the name of a tract the name of the tract will tell you if it's a sending and sensory or descending in motor in most instances there are some exceptions and I'll tell you how to make sense of those let's make it easy first then we throw in a couple of exceptions and you know at all you can be able to answer all the questions you need to know and know if it's a sending in sensory or descending in motor there are usually two words that are stuck together before we get to the word trapped in the knee the first half of the word tells you where the trap - starts in the nervous system the second half of the word shows you are the tract ends these traps are either going to go from somewhere in the spinal cord to the brain or for somewhere up haider down into the spinal cord in most instances so all sensory tracts are going to start with or most of them are going to start somewhere with the word spine up now there's usually not a - but I'm going to put one in here and the second half of the word tells you where it ends so if I tell you I have a spinal dynamic tract that tells you the tract starts in the spinal cord and ends in the thalamus of the brain therefore it must be going up or a sending therefore it must be sensory now when you look at the page 93 the first two tracks are called the lateral spinothalamic tract and the interior spinothalamic tract so there's two spine with the lamech tracks the first word of the name the anterior or lateral tells you which white column you will find that tract in the lateral spinothalamic tract is found in the lateral white column the enter your spider thalamic tractors in the anterior white column so the name of the tract gives you a tremendous amount of information and since it goes through the spinal cord to the thalamus it must be sensory now it turns out that these two tracks carry a lot of sensory information about pain and temperature and very crude touch a very crude sense of touch so you should also know that about the spinothalamic tracts they do pain temperature and some very crude touch okay now I'm going to skip the next two and we're going to do the the last two a sending or sensory tracts of the spinal cord there's a posterior spinocerebellar tract and an anterior spinal cerebellar tract so look at the name spinal cerebellar starts in the spinal cord ends in the cerebellum so what does the cerebellum do the cerebellum does motor coordination so these are going to take proprioceptive information so that we can make we can become coordinated if you're trying to learn how to juggle then they're sending sensory information about your body positioning and if you keep dropping the ball then you need to make some kind of motor adjustment and so they help with motor coordination because they're sending the information proprioception about our body positioning into the cerebellum there's one in the posterior a horn called the posterior spinocerebellar tract there's I'm sorry in the posterior Y column the posterior Y column contains the posterior spinocerebellar tract and the anterior white column has the anterior spinocerebellar tract in it they do a proprioception cerebellum coordination the spinothalamic tracts are doing sensations like touch temperature pain crude touch I should say now the fasciculus Kuni artists and fasciculus gracilis if you look at the word fascicle that starts with F I think fasiq the fascicular are doing feelings they're doing sensation the fasciculus Kuni artists and the fasciculus chrysalis which are part of the posterior white column do some sensations like very fine touch okay they're also doing things like some light pressure and some tactile information and they send that up to our our medulla and then we pass it on there so all six of these tracts the anterior spinal column ik tract and the lateral spinothalamic tract are ascending and they do sensations about crude touch temperature and pain okay the posterior spinocerebellar tract and the anterior spinal cerebellar are sending information about coordination proprioception for cerebellum to coordinate and then the fasciculus crew jnanis and the fasciculus bacillus send feelings of fine touch very fine feelings the EPS so fine touch light touch some very light pressure and vibration in the skin so you need to know that information now when it comes to the motor tracks we're going back up to page 92 for a second we're going to talk about the motor tracks so we have this image of the spinal cord and motor commands coming up so let me erase this information here and we're going to talk about descending or motor tracks I mean this is one of the simplest things and of course my instructors never explained this to us they gave us a thousand powerpoints and printouts and talked to like auctioneers and then when we went to the library we figured this out oh look this is the easy way to think about it descent new tracks are always going to be motor so when you hear the term descending trapped or motor trapped you think of the other term descending motor motor descending because up here in our brain if I'm gonna send motor commands down well that's a really long to do them the thought to initiate them usually start somewhere higher and then descends and then I have a motor neuron going out to muscle we have two neurons usually in the pathway not always but this is a simple way to think about it the top one is called the upper motor neuron because it's higher up in the brain and descends down and then the second one is usually called the lower motor neuron because it's lower in the spinal cord now these are somatic motor pathways if we were talking about autonomic motor then the upper motor neuron would synapse somewhere down here and then the lower motor neuron would still come out but it would go to a ganglion like the sympathy gamely on the autonomic ganglia like we were talking about going to the thoracic and the abdominal pelvic regions we have the preganglionic neuron and the postganglionic neuron okay we did that in the last lecture so but we're going to simplify it and we're just going to talk about these right now but the similar information applies only there's an extra motor neuron in the autonomic pathways the ganglionic nerve the upper motor neuron and the lower motor neuron are the two neurons the upper motor neuron some are higher up and extends down to the spinal cord the lower motor neuron extends from the spinal cord out to an effector or a ganglion if you're talking on autonomic but we're not going to and that's in your notes it's all motor pathways are gonna end with the word spinal or many of them not all of them so if I have a corticospinal tract that begins in the cerebral cortex which as high as you can go you can't go any higher so if it starts in the cortex it must go down and this one goes from the cerebral cortex to your spinal cord must be motor so if you look at the page 93 here's a lot of descending tracts I'm gonna skip the ones that don't play by this rule first so we have a lateral corticospinal tract that means that there's in the lateral white column and it goes from the cortex to the spinal cord and we have the anterior corticospinal tract lateral and anterior corticospinal tracts and they're going to be sending motor commands down to the gray horns of your spinal cord okay we're not going to worry about you know they're all going to be motor commands so we're just going to learn this part so if you have corticospinal starts in the cortex end of the spinal cord must be descending therefore must be motor and then the lateral on the anterior part tells you which white column that they're in the corticobulbar tracts don't always make it down to the spinal cord but if they start in the cortex and I asked you what is the bulbar region of the brain he'll I don't know well if you don't know you still know that it's descending in motor because I can't go any higher than the cortex so it must start in the cortex and come down to something called the bulbar region and these actually control a lot of facial muscles some eye movement some of this higher stuff so they don't necessarily come down into the spinal cord but nonetheless cortical bulbar tracts are motor then we have another one called the vestibular spinal tracts we'll look at the name it starts in something called the vestibule the hell is that I don't know I do know but maybe you don't but and maybe you do who knows but the vestibule or spinal tract ends in the spinal cord it must be descending it must start somewhere higher in a structure called the vestibule and these actually do a lot of um subconscious motor movement about maintaining our balance so it's sort of a lower part of the brain that we're not consciously thinking about for example if your brain says I need to stand up and walk across the room to get something then the vestibular spinal tract there your cortical brain may turn it over to those lower areas and they're gonna make minor adjustments so that we're not falling around like we're drunk walking across the room or very well-coordinated so they're kind of subconscious okay and then we have a thing called the exacto spinal trap and once again what is the tectum of the brain for the tech doe spinal tract well it doesn't even matter if you don't know what it is you can still look at it and say if it ends in the spinal cord it must be coming down so looking at the name very often tells you what it does now the tech toe spinal tracts also do a lot of movement of parts of our our arms and some wear a head and neck so it's all rather complex and there's a lot of overlap but nonetheless you should be able to look at the tract and tell me if it's motor that ends in spinal or it can only come down from the cortex and go somewhere it must be descending in motor now there's a couple that don't play by this rule that are motor tracks but it's easy to think about I always think about when you think about the ancient pyramids in in Egypt somebody had to move all those block to build them so anytime you hear about the pyramidal tracts there are some structures on the medulla called the pyramids the pyramidal tracts were moving things so their motor and then there's some that are just outside of that called the extra pyramidal tracts but they play by the same rules so anything with pyramid in the name is going to be moving it's going to be moving stuff like you had to move stones to build the pyramids the fasciculus gracilis and the siculus Canadia kakuni artists and fine feelings the pyramids are movement so now you know by all the tracks if their sensory or their motor if they're ascending or descending got it all right so now I'm gonna stop there we got one more video to do and we're gonna reiterate the autonomic nervous system and we've really already done this but there's a little bit more detail I might throw at you it starts on page 94 the note set so thanks for watching I hope you learned something I hope you have as much fun as I did I finally got to complete this video yay one more folks and we're done with part 1 a.m. P for this semester you can get ready for part two if your grades are good enough they're not come back and retry part 1 until you get it down anyway see you guys on the flipside hope you had as much fun as I made