Nasal Cavities

00:01 moisten and clean the air. Well, here is a couple of complicated diagrams but I want to just to look at the left-hand diagram first and again try and point out the nasal cavity.

00:14 The very lower part of that diagram on the left you can see the tongue and above that the hard palate and then you have that latter whitish area that represents the nasal cavity.

00:26 And just above it you can see a yellow structure. It happens to be the superior chonchoae.

00:32 I will talk about that in a moment and above that is olfactory epithelium. So just orientate yourself with this particular figure first and then I can go ahead and describe some of the features that we are going to looking at. The nasal cavity itself has three components.

00:53 The nasal vestibule is the very entry into the nasal cavity, the nostril. It is actually the skin, but it is served by a mucous type for protective environment coming from the nasal cavity. The bulk of the nasal cavity you see is really the respiratory region. That consists of a mucosa. Remember mucosa is the internal lining of tubes that are exterior to the body. This mucosa is a very important mucosa and I am going to describe it in more detail in a moment. And then above that, that I pointed out before on that area just above the superior conchae is the olfactory region. That has a very special epithelium that allows us to smell. We will now look across on the right-hand side diagram. This is a section taken as if the person is facing you and the section passes through the nasal cavity.

01:58 The one we looked on the left was a mid-sagittal section taken through the head region.

02:04 Well on the right-hand side, it is important that you have a look at that diagram pick out the nasal septum, dividing the nasal cavity into its two halves and then the nasal cavity itself. But also notice there are three projections. There are three elevations of the mucosa and they are supported by bone within them. Those elevations are called chonchae. They are very very important.

02:35 They have respiratory epithelium, but they increase the surface area of the nasal cavity so that when you breathe air in through the nose, the air is exposed to a large surface area, it slows down. It swirls around a bit and that is ideal for the air to come in contact with the respiratory epithelium to carry out the warming, the moistening and the cleaning.

03:01 Those chonchae have very very large networks of blood vessels and they are responsible for warming the air as well. Notice also on the far right-hand and left-hand sides of the nasal cavity in this image, there are huge spaces called sinuses. Those sinuses are actually also lined by respiratory tract epithelium and there are very small entries into these sinuses from the nasal cavity. Those sinuses drain down into the nasal cavity. They drain all the secretions of the respiratory tract epithelium in that component of nasal cavity, secretes and produces. Now sometimes when we have inflammation of the nasal cavity, influenza a common cold, the mucosa swells and it often blocks off that region for drainage.

03:55 And if there is bacteria present, then they can colonize and we get the condition that we often experience called sinusitis, another inflammatory problems associated with just common colds. Well let us move now to a section through the nasal cavity. On the left-hand side, again it is taken through the front view of a person, a front view through the nasal cavity. On the right-hand side similarly the section just has been oriented just a little a bit off center or right angles, but again pick up the hard palate. It is bone and you can also see the nasal septum and on either side will be the respiratory component of the nasal cavity. You can see that labeled there and then the huge round bulge you see projecting into the nasal cavity, is one of these chonchae consisting of large blood vessels we call swell bodies. And I've already stated of the function of those chonchae.

05:00 On the right-hand diagram, right at the top of the nasal cavity is the olfactory region.

05:06 I am going to describe that in more detail in a moment and down the bottom is the more respiratory region where it is dominated by this respiratory tract epithelium. And then again is the chonchae and again if you look at it very closely you can see it has got within it glands and also the swell bodies or blood vessels that help to warm the air. Well let us have a look at this in a bit more detail. First of all, we are going to have a look at an area just near the nasal septum and we are going to look at the epithelium of respiratory tract mucosa. Here it is labeled here and this type of epithelium then covers the entire nasal cavity, in fact it covers all the epithelial surfaces right down to almost the terminal bronchioles and then it changes and we will have a look at that when we get down to that level of the conduits. Well the respiratory epithelium when you look at it, is a pseudostratified epithelium, meaning the cells appear to be all on top of one another, but it is only because you actually see the nuclei on top of one another. All those cells, in fact, are actually touching the basement membrane. So it is called a pseudostratified epithelium for that reason. And on top of this epithelium are cilia. These cilia are very important because there are glands within the lamina propria, that connective tissue just underneath the epithelium, these glands secrete a mucous and a serous type component onto the surface. The mucous component is secreted by goblet cells within the epithelium.

07:00 You can see it is a very pale staining cell in the epithelium. The serous secreting glands buried into the lamina propria secrete this watery fluid and that watery proteinaceous type fluid is very important because on that watery fluid sits the mucous. And the cilia beat within that serous watery component and as they beat in one direction they move the mucous along the epithelial surface and that mucous is sticky and therefore this epithelium can trap debris that we inhale and move that debris along in that mucous raft to where we can swallow it or cough it out etc and get rid of it from the body. That is a very important part of this respiratory epithelium and the nasal glands underneath remember secreting this serous watery component. There is also lots of blood vessels. In the bottom image, you see a huge blood vessel. That is one of the swell bodies, probably within the chonchae that again warms the air as it pass through the nasal cavity. Let us now have a look at