Identifying Epithelium | Review and Practice Questions — Transcript

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1. 0:00so what i'm going to do is show you one example  of each and then ask a series of questions to
2. 0:07see if you can identify the epithelium i just  showed you using the techniques i just explained
3. 0:13so when you're identifying epithelium you  really need to ask yourself two questions first
4. 0:21how many layers of cells am i seeing
5. 0:25and what are the shape of those cells that i'm  seeing so when you're seeing one layer of cells
6. 0:33that is a simple epithelium
7. 0:36multiple layers of cells would be a stratified epithelium
8. 0:44and our three possible shapes are squamous which are flat
9. 0:51cuboidal which are squares
10. 0:54and columnar which are columns
11. 0:58the only slight trouble occurs when sometimes cuboidal cells
12. 1:02they might look a little bit rectangular so in  that case look at the nuclei if the nuclei is a
13. 1:10nice little circle it's going to be cuboidal
14. 1:14if it is an oval it is going to be columnar
15. 1:20so on our first example we are  seeing a singular layer of square
16. 1:27shaped cells and that's why this  is simple cuboidal so you're seeing
17. 1:37that in a couple examples on this slide
18. 1:43if you were unable to tell what shape these  cells were look at the circular nuclei remember
19. 1:51simple cuboidal has circular  nuclei
20. 1:57In our next example
21. 2:00you're seeing the basement membrane remember  epithelium always has to be attached to something
22. 2:06and that something is the basement membrane and  you have a single row of cells going off this way
23. 2:15and a separate singular layer of cells going  off this way and you can see little rectangular
24. 2:22outlines which is how you know this is simple  columnar now if you couldn't see the outlines
25. 2:30you can also look for those oval shaped nuclei  you can also look sometimes but not always
26. 2:38you'll have these specialized little  cup shaped cells called goblet cells
27. 2:46in the next slide what you're seeing  is the same type of epithelium at two
28. 2:51different magnifications so when you're looking  at it at a high high magnification you can see
29. 2:59one layer of flat cells so this is simple squamous
30. 3:14in this example your first instinct is  to probably think that you're seeing
31. 3:18multiple layers of cells because you're seeing  multiple layers of nuclei but what you're
32. 3:25actually seeing is you have a little short  cell here and then you have some tall cells
33. 3:34but they're all attached to the basement membrane  so this is really only one layer so this is the
34. 3:44ciliated pseudostratified columnar epithelium it  is called ciliated because it has cilia on top
35. 3:54pseudo stratified "pseudo" means fake like  pseudoscience is fake science pseudostratified
36. 4:04means fake layers and the taller  cells would be column shaped
37. 4:13in this example so this is the basement  membrane down here you're seeing many cells
38. 4:24so it is stratified and if you pay attention  to the shape of the cells at the top
39. 4:30you can see they're very flat little pancakes
40. 4:35so this is stratified squamous even though  the cells towards the bottom are more
41. 4:43cube shaped we only care about the cells  on the top when we're picking the name
42. 4:52and this last example does not follow the  naming pattern so it is stratified because
43. 4:58there are multiple little layers of  cells stacked on top of each other
44. 5:04but they're not really squamous they're not  columnar they're not cuboidal so this just gets
45. 5:10its own name this is transitional epithelium  so if you're looking at an epithelium that's
46. 5:17stratified and you feel confused about the  shape it's probably transitional your other
47. 5:22hint is if you look at the top usually the  cells at the top look like little bubbles
48. 5:41so now i want you to think for  yourself what am i looking at
49. 5:51how many layers what is the shape
50. 5:56so what you're seeing is simple columnar because  we have a row of cells going in this direction
51. 6:04a row of cells going in that  direction and these nice oval nuclei
52. 6:10also kind of a giveaway is the goblet cells  not every single example of simple columnar
53. 6:16has goblet cells but if you see goblet  cells it's pretty safe to say it is simple columnar
54. 6:39so the answer to what this is you're seeing one  layer of squashed cells
55. 6:47so it is simple squamous
56. 6:59so looking at this example i'm asking  about these cells here and here and here
57. 7:13so we are seeing one layer of  square cells so it is simple
58. 7:20cuboidal so we have one layer of square cells here  a basement membrane and then a different layer of
59. 7:28square cells here they're not perfect squares they  are a little dome-y at the top but you definitely
60. 7:35shouldn't confuse this with transitional  because transitional is very clearly stratified
61. 7:53so we're seeing multiple layers of cells the  ones near the top are squash little pancakes
62. 8:02that's how we know it is stratified squamous
63. 8:18so i'm interested in this part of the
64. 8:21slide
65. 8:30you're seeing multiple layers of cells because  you have all those rows and rows of nuclei
66. 8:37you don't see any cilia on top
67. 8:45and it doesn't look squamous cuboidal or  columnar so this is our
68. 8:53transitional epithelium
69. 9:15so this would be the
70. 9:19ciliated pseudostratified columnar epithelium
71. 9:26because we've got those cilia on  the top which is a dead giveaway um
72. 9:32and these cells are kind of tall and skinny  with some shorter cells on the bottom
73. 11:35now this is a bit of an advanced  example but let's see if you can get it
74. 11:38just for funsies i'm actually interested in two  different things here ignore what's at the pointer
75. 11:45pay no attention so there's this  here what do you think that would be
76. 11:53and then there's also this here and there's  other example here what are we looking at
77. 12:05so this first thing you're seeing one little layer  of squashed pancake cells that's simple squamous
78. 12:16and this
79. 12:22even though you can't pick the individual  cells apart very easily you see those circular
80. 12:29little nuclei and they're kind of like in a  cheerio formation which you see a lot with
81. 12:40simple cuboidal
82. 12:47so i feel like for most beginners most  professors just ask you simple squamous
83. 12:53on like a lung slide which is what i showed  you before that has lots of empty space
84. 12:58however it doesn't hurt to know what it  looks like in other organs this is a kidney
85. 13:06Alright, I hope it was helpful if you did not  understand why you were wrong about anything
86. 13:11just leave a comment and i'll try to explain  as best as i can um i hope this was helpful i
87. 13:16hope you feel great about how much you  know have a wonderful day and have fun learning