 So, the next tissue we want to think about is called simple columnar epithelium. Simple one cell layer thick columnar column shaped cells epithelium. And so, to show you simple squamed or simple columnar epithelium, we want to look at a micrograph of the small intestine. So the small intestine is a hollow organ, of course, when you eat food it goes to the stomach first and is churned in the stomach and mixed and then the time from your stomach goes into the small intestine. So on the micrograph or on the microscope we have the micrograph of the small intestine and I'm just going to scroll around so you can see that it's a circular structure when we look at it in cross section and again if you think about having a tube that's hollow so like my arm if my arm were a hollow tube if we cut it cross ways and looked at it right at the end we would see a circle and so that's what we're seeing here. Now the lumen of the small intestine is what the food actually moves through. The lumen is the hollow space inside the intestine and there are a lot of little finger like structures that project into the intestine and you'll learn about those when you cover the digestive system but what we want to do is go up to higher power and look at this tissue in more detail. So I'm going to adjust the microscope so we can see the tissue that we're interested in. I'm going to look at if I can't find a section that shows a couple of different things. Here we go. So this is an example of the simple columnar epithelium and you can see a cell here with its nucleus, a cell here with the nucleus and here's a cell and this structure is called a goblet cell. It's a little hard to pick out. I'm going to erase what I drew there but you can see this area is a goblet cell. The goblet cells secrete mucus, there's one, there's one, and there's one. So simple columnar epithelial tissue will have some goblet cells that are involved with mucus secretion. Let's scroll around and see if we can find another area where we may be able to see the nuclei a little better. Again, this is all about how the slide is made and when the slide was made a small intestine probably from a mouse was actually cross-section. So here you can see the tissue a little better. This is the lumen, change that to black. And I want you to notice here in particular that when we look at these cells, the nuclei are sort of all found in the same layer. Here's another nucleus, here's a nucleus, here's a nucleus, here's a nucleus. So we could separate these cells sort of like this. Here's a goblet cell that we looked at and here's another goblet cell. So if we wanted to draw that tissue it would look something like this, which is pretty much what we have over there, we'll have nuclei all in the same level near the basement membrane and then we'll have an occasional goblet cell. Now this would be the lumen, so this is the free surface of the tissue. Now this tissue has several functions, one is protection. When we look at this as a thick cell and that thickness leads onto some protection, we also have secretion as the goblet cells secrete this mucus which actually helps to protect the surface of the cell as substances slide across. And it's also involved with diffusion and osmosis as nutrients and water will move across this membrane and into ultimately the bloodstream. So simple columnar epithelium and we've looked at a micrograph of the small intestine to demonstrate this tissue. And that's it.