hi everybody and welcome back to miss Angler's biology class I am Miss angler in today's video we are going to look at the updated version of my vestibular apparatus video in other words we are going to cover the semicircular canals and the utriculus and sacculus which are responsible for posture and balance this video is going to replace my old set of videos that I made during lockdown I've made the topic even easier shorter and more applicable to what we're going to be doing in our finals coming up this year now if you are new here don't forget to give this video a thumbs up and make sure you're subscribed with your notifications turned on because I post every Tuesday and Thursday and don't forget everyone finals are coming up and if you need to get your hands on the cheat sheet study guide then you can find it on my website Miss anger. co.za and if you have any questions on the topic we are covering today and you'd like me to ask answer then don't forget to put that in the comment section below now it's at this point everybody that as we jump into the content we need to make sure that we are all looking at exactly the same thing when I speak about the vestibular apparatus we are talking about everything that is past this line that I'm going to divide in half here now so we are talking about this side of the diagram this side over here we've actually already covered that that is the cocka and it's the structure we hear with if you don't know much about the cocka and how we hear then I've linked the video up above now for you to go and watch that but we are going to be talking about the vestibular apparatus and it's importance in maintaining posture and balance and I'm going to make sure by the end of this video everybody that you are able to answer these questions for full marks um so that you're able to explain your s well enough and use all the correct terminology now one of the biggest misconceptions about the ear is it is therefore hearing but in actual fact it doesn't just hear it also enables us to maintain our posture which if we're not so sure what that means posture means upright like is your body standing upright or are you lying down and the other thing that it maintains is our balance now balance and posture are not the same thing don't get them confused posture is upright so is your body up or lying down balance is when you are able to determine the speed or the rate at which you are walking or moving and that's your balance kind of like how you maintain your balance while you walk forward or when you walk backward now I'm going to start my explanation with these structures over here the semicircular canals you will notice that you have three of them and the reason for that is you need to have one Canal for every uh like zone of movement and the three zones would be something like up and down so that's the body moving up and down like jumping up and down two would be moving forward and backward and the final one would be from left to right or in this case I'm going to go side to side in other words you're moving from left to right or you're stepping sideways now you need three canals so that you can sense your body moving in these three ways and that makes sense because while we're walking while we're moving we need to be walking forward and we need to maintain our posture and then all of a sudden something jumps out at you and you have to move to the left that would be maintaining your balance and moving your body suddenly to the left but how does that actually work so what we have in front of us is a cross-section through one of the canals and this is what we need to know first of all the canals are filled with a fluid called endolymph and that fluid is going to slush and move around as you walk now it's going to um stimulate a receptor which is the chiste now the chiste is this structure uh at the bottom over here this is what we want to stimulate when we are moving the body in space but now how exactly do we do this well we are going to speak about how the endolymph moves due to a change in speed or Direction so I want you to imagine this fluid is flowing through this canal all the way around and it gets to the other side and it stimulates this jelly like structure called the ampula and it's got a cap over it and basically it bends over so the fluid comes rushing over and it makes this structure which is standing upright it bends over to the side it gets pushed over and that pushing over generates an electrical impulse that goes down the vestibular nerve telling your brain that you are leaning over to the left or maybe you're moving forward or moving backward and so it's the movement of the lymph stimulating the cristate but how do we get a full Mark set for this well I'm going to show you all the points you need to hit in order to get you know seven out of seven full marks perfect answer so now let's move this diagram over to the side here and let's introduce our description now if you like this description I'm about to use I want you to know that you can actually get this in my cheat sheet study guide and this is how you are going to get full easy marks so first thing what you need to do is you need to describe that there is a change in speed and direction that's really important we must acknowledge that we then need to say that we stimulate the chiste the chiste being this structure here at a that is our receptor where is our receptor that is inside the semicircular canals which is this entire structure here at B now we stimulate it and that stimulus is converted to an impulse and grade 12s I think it's really important to include this point a lot of us leave it out and it's becoming very common for examiners and markers at the end of the year to almost ignore the rest of your answer if you don't put this single line in in other words they just stop marking the rest because it means you don't understand how impulses are made and converted Etc so as impulse is converted and that impulse is transmitted to the cerebellum which remember is the smaller region at the back of the brain and that is responsible for maintaining balance and muscle tone it's sent there via the auditory nerve I know some textbooks might say vestibular nerve but I want want you to know that the vestibular nerve doesn't go all the way to the brain so it has to go to the auditory so you could say via the vestibular nerve and then the auditory nerve or you could just go auditory and you'd be good and the final point which is often what we forget to mention is the cerebellum sends an Impulse to the muscles to restore balance and remember that's what semicircular canals are doing they are maintaining your balance so every time you see semicircular Canal I need you to think of balance and that's how you would get full marks if you had to describe this in an exam most of the time they'll give you a situation they'll say something like you had to dodge out of the way when someone threw a frisbee at your head explain how the semicircular canals maintained your balance now we're going to move on to the utriculus and sacculus now this is an area in the V cular apparatus if we have a look at the diagram here where it's in this like lower kind of swollen region below our semicircular canals and you have two you have a utriculus and a sacculus and their main function if I were to tell you is posture and remember posture is how the body is positioned so in other words are you standing upright or are you lying down down or are you upside down and we need two of these because you'll see now you can have two basic positions of the body the utriculus is going to tell us whether we have our horizontal right so that means that this is what's going to tell us our body is you know like lying down or on the horizontal whereas the sacculus is up and down and that means we're going to use it for vertical posture which means you know like standing and these are what's going to tell our brain whether we are standing lying down upside down are we moving from a lying to standing position that's what posture is now we need to know some details about how all this works and just like the semicircular Canal there's going to be receptors there's going to be movement but luckily for us we actually need to know very little detail about the structures of the URI and sacculus all we need to know as you can see here is there is a group of um sensory cells and the names of those sensory cells so the only thing we really need to know is the name of the receptor cell which is called our macula now macula is the receptor just like we saw earlier in the semicircular canals they had christe our utriculus and have the macula or macula and that's what's going to receive the information and essentially yet again it is going to be sensitive to gravity and that's how it knows which way is up unlike the semicircular canals that are going to just rely on that fluid moving inside of those um canals we're going to rely on gravity and essentially gravity is either going to pull down or it's going to be evenly spread out like in the horizontal and that's how our brain knows we're upright or lying down but how do we get full marks if we were asked for example how does someone maintain their posture when they're sitting in a chair like they're sitting upright how do they maintain that or they're lying down on a bed how do they get up and stand up straight how do they maintain that posture this is what you're going to say once again we're going to shrink this down and we're going to move this out of our way so that we can insert our little description here and so yet again here are our bullet points first bullet point that we are going to cover is there is a change in the position of the head in space so we must acknowledge the head is changed it's no longer lying down it's now upright the next thing we're going to talk about is there is a stimulant and the stimulant is going to go to the receptor which we mentioned earlier is the macula which is this structure I've labeled here now a the macula in the utriculus and sacculus which remember is we are going to identify the locations so there is our utricle I'm going to make it B1 just like my description and B2 those are going to then be stimulated and they are going to take that stimulus and once again they're going to in convert it to to an Impulse again Matrix we always forget that sentence please don't forget converting a stimulus to an Impulse that impulse yet again is sent to the cerebellum the cerebelum does a lot of work when it comes to balance and posture okay now it's up to the cerebellum to receive this via yet again there it is the auditory nerve again you could say vestibular nerve then to the auditory nerve but I'm telling you from experience from a trick marking they want auditory nerve they don't want vestibular nerve that nerve then sends for our last Point here a message via the cerebellum and it goes from there to the muscles to restore this time posture and the focus is on posture here so you'll notice that this explanation is very similar to the semicircular Canal so you run the risk of confusing the two you need to work on how you're going to remember the two but what's nice is that because they're so similar it's almost like you just learn the one and then substitute in simple differences which if I were to highlight the simple differences it would be the receptor the location of those receptors and then what we're changing so in this instance we're changing posture instead of balance now as always I like to finish off my videos with a quick terminology recap and you can use these for flash cards and quick r Vision but we first started off speaking about the vestibular apparatus and how it's divided and we spoke about the utriculus and the sacculus and those are two swollen regions with a receptor cell inside of it that's going to be able to tell you whether your body is upright or lying down and we Associated that with posture the um receptor in those two structures is called the immacula so that's what you find inside the utriculus or the sacculus and they send a message to the cerebellum which is responsible for maintaining our posture and our balance speaking of balance we also need to talk about the semicircular canals we learned right at the beginning of the video where we spoke about these three canals that tell your body if you're moving forwards backwards up down left or right and they have a receptor cell in them called the criste and and this receptor or group of receptor cells all send information via the auditory nerve to your cerebellum to maintain your balance now if you like this video don't forget to give it a thumbs up and make sure you're subscribed with your notifications turned on and please leave any questions or comments in the comment section down below any videos you'd like me to redo or re-explain or any topic that you can't find in the grade 12 playlists make sure to put that down below and I'll see you all again soon bye