Inner Ear

by Jason Amores Sumpter
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the inner ear is the portion that actually contains the sensory receptors that are responsible for detection of sound, and they're going to be involved in balance. Now. The balance detecting system is called the vestibular system, and it's basically attached to the sound detecting system. The vestibular system is made up of these semi circular canals, these three fluid filled cavities that you can see here on the inner ear structure and essentially fluid is going to move through these canals and stimulate hair cells in them. And that's how we're going to be able to detect rotational motion and get a general sense of balance. This is why, for example, is a kid you know, when you spin around a lot, you get dizzy. It's because the fluid is still moving through your semi circular canals due to inertia. So you're still getting that perception that you're moving even though you've stopped. Now the co KLIA. This structure is what's going to be responsible for the detection of sound, and it's a spiral shaped cavity, and it kind of looks like a cone that got coiled up. Now you can see a sort of a modified version of the cochlear here, which is made to look like what the co. Cleo would appear as if it were uncoiled. That's why it's all straightened out. However. In reality, it's, you know, structure is all curled up. So imagine taking this and then rolling it up like a fruit roll up or something. No, the CO CLIA has a bunch of different structures in it. You don't need to worry about all of this, but I'm just going to give you a general sense of what's going on in there so that we can talk about the part that you do need to understand. So the cochlea actually has three ducts in it, or three fluid filled tubes. There's this one on top we call the vestibular duct. There's the Tim panic duct on the bottom, and then in the middle we have the cochlear duct. Now the hair cells in the cochlea, that air going to be responsible for detecting sound, sit on something called the basilar membrane. This is the membrane kind of in the middle of the cochlea. That's gonna be underneath the cochlear duct and above this Tim panic duct. But really, you only need to know about the basilar membrane because that's what the organ of Corti sits on. This is the structure that contains many hair cells. As you can see, here we have our organ of Corti and all these little projections on the top are our hair cells. And, uh, this these air the hair cells that are gonna be stimulated to perceive sound. Now it's worth noting that the basilar membrane is different in different regions of the Coakley A it it will actually have different regions that vibrate at different frequencies of sound waves. And in this way, we're able to better perceive ah, wider range of sound frequencies. No, how these hair cells in the organ of Corti air actually stimulated has to do in part with something called the Tech Torrey. Um, membrane, this is gonna be a little membrane. Could see it here that sits above our hair cells, which are here in the organ of Corti. No, basically, when a when the stay peas hits the oval window, it's gonna send a wave through the fluid, um, of the coke Leah. And that fluid moving is going to vibrate those membranes. And those membranes are going to move when they vibrate, right? That's kind of what vibrating means, But that vibration is of the basilar membrane is going to cause those hair cells to bend due to their connection with the tech Torrey a membrane, although it's worth noting that not all hair cells are going to be connected to the tech Torrey a membrane and I should point out that this process is not super, super well understood. So, you know, in 10 years time or something, maybe what I'm saying well, no longer be held is through the standard of the day, so not totally well understood. But there is an interaction between those hair cells and the territorial membrane, and it's those hair cells being stimulated. That's going to lead to the perception of sound. And again, remember that the amplitude of the wave translates into volume, and the frequency of the vibrations translates into pitch. Now I also want to point out that there's the structure called the round window. That's kind of all the way. At the other end of the cochlea and its job, it's It's a membrane covered opening like the oval window, but its job is to dampen waves and prevent reverberation. Essentially, this is going to allow, uh, the waves to sort of defuse their energy out of the cochlea. And, uh, you know, make sure that they're not just reverberating or like echoing around inside there. So with that, let's actually go ahead and flip the page.