hi everybody and welcome back to miss angler's biology class i am miss angler and in today's video we are going to be covering a nervous system question um from a past paper and this particular one is going to focus on the ear it is a little bit more challenging than what we've done before now if you are new here don't forget to give this video a thumbs up and subscribe and make sure you turn your notifications on if you'd like to pause the video now please do so so that you can attempt the questions first before i walk you through how to answer these questions adequately and how to interpret the diagram also if you're in matric and you're thinking about improving your marks or you're trying to get that distinction in your final exams you should think about joining my membership in my membership you get access to way more of these exam walk-through questions you get live lessons with me and you also get access to my summary cheat sheet notes so let's begin to break down the diagram it just simply says that we need to study the diagram of the human ear below and it's a very stable normal diagram something we see regularly of the year in actual fact in most past papers they just recycle the same ear diagram over and over and over again so once you actually get used to looking at this one it's pretty similar in almost all exams now i always tell my matrix to label the diagram before they even begin so that they familiarize themselves and they're confident in their answers so we're just going to run through some of the labels um a is pointing to the set of bones in your inner ear or your middle ear excuse me which are the ossicles and b is our nerve now technically it's two nerves it's the auditory and the vestibular nerve um then we have c which is the cochlea and then we have d which is the round window and then we have e which is the tympanic membrane and what they've done in the cochlea as well by the way where where they've labeled c is they've just stretched it out a little bit so that you can see its whole definition and then they've provided the label for semicircular canal so the first question literally says identify b and d well we've identified b as our auditory nerve and d as our round window now for some of you the round window is actually missing in your text box if you're not sure what the purpose of the round window is it is essentially the exit point in a cochlear so the oval window is where you go in and the oval window on this diagram is this little hole that we can see over here whereas the round window which is labeled at d is the exit point and that's because sound waves go in and then they need to come out somewhere when they are excessive and there's too many of them now even though this question is focusing on the ear the next question is asking us to say which part of the brain will receive impulses from part c so this is the cochlea in other words what part of your brain do you hear with and you hear with your cerebrum um you don't need to know the specific lobe names i know in some textbooks they do have the labels of the lobes but according to the guidelines you don't need to know the lobe name however if you are not writing an nsc paper and perhaps you are writing a different exam perhaps an ieb you may be then asked to write this specific lobe of the cerebrum where this goes to now for question three it says describe the role of the semicircular canals in maintaining balance now remember whenever we see a described question we're saying how it happens where it happens when it happens and why it happens now this is for five marks which means it requires a lot of detail in the answer i actually have notes on this for those of you who are members and i've given you the perfect answer that you can learn off by heart and to provide for this in the exam but when you are answering this question what you need to do is you need to acknowledge that there's a stimulus that then stimulates the receptor in the semicircular canals which is the cristae the cristae are stimulated by a movement in the endo lymph which is the fluid inside the semicircular canals that then generates an impulse which is then sent via the auditory nerve to the cerebellum and the cerebellum is going to send impulses to your muscles in order to maintain your balance and you always want to round off talking about the muscles because they're the effectors and they're the ones who maintain your balance as you're walking or you're moving again you can find a link also to the video that describes this very very well and i've linked it just above there it also has the memo answer attached to it so the next question is a little bit tricky application question it requires you to know quite a bit of the structure of the ear and the functions of these components and it says describe how an increased production of mucus in the nose and throat may lead to a bursting of part e so basically um part is our tympanic membrane our eardrum and they're saying that mucus is building up um inside the throat and the nose how would that lead to the eardrum boasting so now you've got to imagine that mucus is filling in this space over here in the middle ear and there's actually two answers that you can go with the first answer is linked to the astution tube which is this tube at the bottom over here and that is where excess mucus drains away now if it's blocked then you would say something like the estrogen tube is unable for air it's unable to let air in to the middle ear therefore causing pressure on the tympanic membrane which may lead it to burst or the alternate answer is instead of speaking about the air and not being able to maintain the pressure you could say that mucus moves up the estrogen tube into the middle ear pressing on the tympanic membrane causing pain and possibly then bursting the eardrum so either you're going to talk about the fact that the air cannot be maintained so the air pressure cannot equalize or you're going to talk about how the mucus drains into the ear and how the mucus is pushing on the ear so it's either about the mucus or the air but you've got to know that the extrusion tube is a key component of that now the last question goes into and explain why fusion of structures at a may lead to hearing loss now first of all you need to know what a ar they are ossicles fusion means stuck together in other words they are unable to move remember the ossicles are three individual bones that beat into each other sort of like a domino effect that one knocks into the next now if they're fused they're attached to one another so how would this lead to hearing loss it's an explained question so you can make a statement and then you're going to provide a reason so you would say something like if the ossicle bones are fused together they are unable to move slash vibrate therefore they are unable to pass on the vibrations to the cochlea resulting in hearing loss so we're making a statement saying they can't vibrate and if they can't vibrate and pass on the sounds then they can't pass that sound onto the cochlea now here is the memo for you to go over and familiarize yourself with i suggest paying close attention to this one over here 3.4.3 this is a perfect memo answer of how to describe how we maintain balance keeping in mind that we must always remember to mention the receptor the change in the stimulus what's stimulating the receptor and then ultimately how the nerve impulses are sent along the auditory nerve to the cerebellum and how our muscles restore balance the second question i think you should take some time going over and its answer is this a tuition tube question over here i need you to know what the estrogen tube does and the fact that the institution tube won't let air enter or leave the ear causing an equalizing pressure imbalance or like i said the other answer is the astution tube doesn't allow uh so i say that the mucus in the estrogen tube is not draining away and it causes pressure in the middle ear and that pushes on the tympanic membrane so just pay attention to those two particular answers because they are quite tricky now if you like this video don't forget to give it a thumbs up and subscribe and i will see you all again soon bye