hi everyone welcome to Professor long lectures anatomy and physiology I'm professor Pablo I'm teaching human anatomy and physiology part 1 and part 2 these videos are designed or set up for my students taking my classes this particular video is set up for my a and p2 class human anatomy and physiology part 2 this is the fifth I believe video in the sensory physiology series we're going to be covering the sensations of taste and we're going to start the eyeball one of the things I'm learning this is kind of a crude setup as you guys know we're in the coronavirus shutdown of the Koba 19 shutdown and I traditionally teach face to face but because our our inability to go to campus and meet in large groups we've moved the classes to online I'm shooting these with my cell phone and it's a rather crude setup I'm not very technologically savvy so what I've realized is my videos cut off right about 33 minutes but the phone automatically starts a second video why I don't know but I'm not losing any content thank goodness none of those I could shoot these with my laptop but the videos are much darker and green here they suffice and some of the videos may be shot by my laptop so the ones that are bright and sharp are cell phone the ones that are dark and grainy or laptop I'm trying to use the cell phone but it's much harder and slower to load these into YouTube I know you don't need to know all that but that's what's going on here so I'm going to be covering the station I'm gonna start some of the eye physiology but we're gonna have several lectures over the eyeball because it's a lot of information if you're are in my class we're going to be on page 10 of the note set we're going to start the station or the sense of taste and we're somewhere around page 570 in the lecture textbook if you want to follow along and they adopted lecture text okay so gas station is our sense of taste the receptor cells that detect the gustatory molecules are called gustatory receptors okay now the gustatory receptors are located on the little bumps on the surface of your tongue that stuff right so those little bumps are each called a papal ax when you see this term and you'll see this term a lot papal it really means nipple like a little bump sticking out and so you have happily on the surface of your tone those happily have different shapes and different names based on their shapes and they also some functions somewhat differently it is on those little bumps that we have the olfactory receptor site D the gustatory receptor organs called taste buds and within the taste buds are the olfactory receptor cells they're called taste buds because they look like little bugs like a little rosebud we're gonna go in all the anatomy and detail of that the sense of gustatory transduction is so close to olfactory transduction which we just finished that I'm not going to go into the steps because they're almost identical or they're pretty close so as you know the gustatory perceptor cells are a type of chemoreceptor just like well factory receptor cells are but they do external chemo reception so the sense of smell the sense of taste are very closely linked very anatomically similar and physiologically similar okay so now when we look at the surface of the tongue if we're cruising along the surface of the tongue there's usually a little fold and then there's these little structures that stick out okay that's fold by the way is very often called a taste trench okay like a trench or ditch in the ground and the structure sticking up is the Pecola based upon the shape of the Pecola they get different names so if the bacala look around they're sort of sharp or almost hair like the term Philly and the word fellow if until I all refer to hair they're all related words so we call these filiform papillae filiform papillae are hair like papillae and they're very narrow and slender and they're located you know a lot of times near the tip of the tone now one of the things that we know about filiform papillae is they're really not involved in the sense of taste a whole bunch they do a lot of grip and ten sure they can detect textures they can detect gripping but they're not really super involved in the sense of taste and that they don't have a lot of taste buds if any there's another one that comes along that looks like a little fold in a tone and those are called folate Tapani folia are folds so they're little folds on the surface of the tongue and then we have some that actually stick out like a little mushroom or button and those are called funds your form happily find your form in the shape of a fungus so fungiform papillae look like a little mushrooms a little button mushroom button sticking off the surface of the tongue they're nice and smooth and rounded these actually have quite a few taste buds on them and those little taste buds are all over the surface or the edges of them and the last shape we're going to look at actually has several layers to it sometimes and then a button in the middle and all of these layers have taste buds on them so these have the highest number of taste buds now when we study the ions if you study ions and atoms and chemistry you learn that the electrons travel in little layers are little orbitals and the outermost is called the valence orbital wandamae refers to wall and since these walls actually go around if I were to look down on top of this it would look like the button in the middle there would be a gap and then there would be a wall a gap and another wall so they almost look like a target sign so to speak what we've done is we've cut it in half this way and we're looking at it from this angle this is the button in the middle these two walls are going around because they have so many layers there's more surface area for motor takes most more taste buds so these type of pappa leaves have the highest number of taste buds and they are called circum valve eight happily paplu singular happily would be plural circumvallate means walls around now all these different appellee are located in specific locations on the tongue but ultimately what you need to know is that the filiform don't have to any taste buds so they're not functioning at taste they do grip and they can detect texture so it makes a cat's tongue rough is that they can stick their tongue in a liquid and the liquid sticks to these and it pulls some of it in fungiform papillae have you know five ten or so there but you know maybe it doesn't taste buds quite a few phobic happily similarly and actually the phobic faculty are located a little bit further back on the tone than the fletcher form and then the circumvallate are near the very back of the tongue and they have the highest number of taste buds okay so you should know their Anatomy now it turns out that the taste buds themselves can detect basically four primary taste sensations there are there's some evidence now that there's a fifth a sixth and maybe even a seventh taste that we can detect but we still refer to these as the four primary taste sensations and then we'll add so many other tastes our tongue actually has some geography to it there's actually thing called the geographic tongue some people were sensitive to really hot foods the papillae on their tongue can start to retract and it looks like there's a little flat or bald spots on the tongue and then they come back so it's an interesting feature of the tongue so sometimes if you if you're working in healthcare parents freaking out because their kids tongue looks like it has some little flat spots on it where the papal e disappeared they call that a geographic tongue there is a geography to the tongue in a different sense and that the location of the spackling is very specific okay so if we were to look at a giant tongue here you would realize that the four primary taste sensations we're going to list them and then we're going to talk about some mothers the fur for pregnant taste sensations the first one is sweet we have sweet receptors there's two camps on this and I want to explain something it was originally thought by a guy who did a bunch of these studies if I took the sweet receptors in green the highest concentration of taste buds that detect sweet tastes are near the tip of the tongue okay now some people thought that you only detected sweet at the tip of the tongue that's not true you have sweet receptors all over the tongue but the closer we get to the tip the higher and concentration they become and so this part of the tone is really really sensitive to sleep we can detect sugar all over the tongue but we really have the highest concentration of sweet receptors near the tip we're most sensitive there the second sense that I'm going to talk about is salty salt receptors those happily those taste buds that are sensitive to salt tastes tend to be in the highest concentration over here on the sides of the tongue near the front that doesn't mean we don't have any near the tip of the tongue or in other locations you know salt receptors all over the tongue but we do have the highest concentration in these areas here and they'll overlap the salt receptors okay that's why we like to combine sweet and salty sometimes together a third taste sensation would be sour sour receptors are located further back on the tongue at least in the highest concentration way back here and they will overlap some of the others again that doesn't mean we don't have any sour receptors in other parts of the tongue but if you're going to taste something sour and you put it on the tip of the tongue it's less impact than if you put it back for the higher concentration and the sour receptors are some people believe or it used to be taught that we only have sweet here only have salty there only had sour there and then some people realize they're all over the tongue if they blew that whole theory out of the water and said it doesn't exist well it's actually somewhere between we do have the higher concentration of sweet salty and sour in different locations again we have them each one of them all over the tongue but they are kind of locally concentrated the last of the four primary taste sensations is going to be bitter to the bitter receptors are very far back on the tongue and occupy this area here okay doesn't mean we don't have bitter receptors and other locations but when you taste something really bitter it gets you on the back of the tongue so to speak so now there are some other taste sensations that are not part of the four primary taste sensations but when we want to taste foods those foods that give us the greatest pleasure are those meals that combine some have some combination and balance of sweet and salty and sour and bitter so that we get a little bit of everything and those are the meals that really really really speak to us so we also have taste receptors for what they call umami it's my understanding the word Amami is a Japanese word for broth and what these can detect is the presence of protein particularly the amino acid glutamate amino the amino acid glutamate is abundant in a lot of proteins and so you know if you ever watch survival shows when people are starving one of the things they complain about is the need for protein for the body and so when we detect the presence of protein it's important we need to replace the proteins in our body in order to stay healthy and so glutamate receptors or umami are very very abundant and if they really are found associated with a lot of these circumvallate papillae near the back of the tone there are some people that believe we have water receptors that can detect the presence of water or moisture and those are really way back here like when your throat's getting dry when you become dehydrated you crave watery stuff there's some that detector peppery flavors there's a protein called capsaicin that's present in peppers and jalapenos and things and we can detect the the sensation of heat or peppery flavors but those really aren't considered the primary taste sensations and there's some controversy as to some of these but nonetheless so one of the things we do know is that the protein capsaicin which provides the heat sensation when you do eat something really hot really likes to bind the sweet receptors and then really burn your tongue where all the sweet receptors are that's why in order to dissipate the sweet you need to drink something really rich and sugar to out-compete those capsaicin proteins for sweet anyway that's just a little side trivia so you need to know the four primary taste sensations you need to have an idea of where they're located on the tongue you also need to know this if I divided the tongue into three major regions the anterior two-thirds of the tongue are monitored by the cranial nerve number seven and then the back of the tongue is monitored by cranial nerve number nine so cranial nerve seven and nine are monitoring a lot of these taste sensations on the surface of the tongue if we killed cranial nerve seven you would lose a lot of sweet and sour taste you would be they would become less strong to you if you destroyed cranial nerve number nine then you wouldn't be able to detect some of these sensations so no cranial nerves seven and nine if you go through the cranial nerves remember tool Factory optic oculomotor trochlear trigeminal abducens vestibulocochlear factory optic foramen and do since facial facial nerve the stupido cochlear glosso pharyngeal so the facial nerve and the glossopharyngeal nerve are monitoring the tongue sorry I drew a blank there for a second my son's walking through the house asked if we can go work out so I got distracted for a moment anyway now when it comes to the anatomy of a taste bud so let me do this last little bit and we'll stop here we'll save the eyeball for another lecture I'm going to raise all this information and we're gonna actually look at an individual taste but okay so if I were looking at one of these papillae like this and I had these little taste buds these little pockets of cells on the side here if I magnified one of these and looked at it it would look like this I would have this little opening and I would have a little pocket that houses all these cells that opening by the way is defined as a taste for now there are going to be some cells sitting inside the taste bud that are going to be long narrow cells that look like they have these little hairs or cilia sticking off and then they'll send their axons into the tone these cells they're starting to look like olfactory receptors because they're very similar to them and they'll stick their little taste hairs or cilia out of the taste floor so that they can bind to gustatory molecules okay so when you taste something the gustatory molecule will bind to those receptors trigger our signal transduction cascade and fire an action potential into your tongue and then that would go out those axons would go out one of the two nerves that we just talked about cranial nerve seven or cannula at night now mixed in with these neurons are some cells in between them called support cells so these purple cells that I'm drawing are support cells and just like if you watch the faction gustation is only the second known type of neuronal replacement these taste receptors these gustatory receptor cells who live about ten days to two weeks and then they die and we're replacing them so these support cells will grow up and develop into new gustatory receptors they'll develop some cilia and an axon and rewire and at the base aren't going to be some basal cells the basal cells are highly mitotic they are dividing by mitosis the old cell stays behind the new cell develops in those port cell which develops into an olfactory who's our gustatory receptor so it's almost identical to olfaction only we don't really have the lamina propria that would be in here in the space of the tongue okay so know that there's two types of neuronal replacement that we know of in the human body and adults which is olfactory receptors and gustatory receptors and the sense of smell and tastes are very closely linked it's a matter of fact if you pinch your nose and you try to taste something your ability to taste it the intensity of the sensations and the ability to detect different flavors is decreased our sense of smell enhances our sense of taste that's why when you're cold and stuffed up or have the flu not everything tastes good so anyway again as we age these gustatory receptors become harder to replace and our ability to detect different aromas and different flavors declines as we get much older as my professor once said jokingly this is why you can go eat at Luby's five or six days a week when you get older and everything you know it tastes so great and what it really all just tastes the same anyway I'm gonna stop there for gustation I think we're done with that I hope you learned something I hope you had as much fun as I did and hope to see you on the flip side in the next video where we're going to start talking about the anatomy of the eye and the physiology I thanks for watching