Tissues, Part 2 - Epithelial Tissue: Crash Course Anatomy & Physiology #3

Today on Crash Course Anatomy & Physiology, Hank breaks down the parts and functions of one of your body's unsung heroes: your epithelial tissue.

Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App!

Chapters:
Introduction 00:00
Proper Epithelium & Glandular Epithelium 1:38
We're All Just Tubes! 2:12
Cell Shapes: Squamous, Cuboidal, or Columnar 3:34
How Form Relates to Function 4:15
Layering: Simple or Stratified 5:26
Epithelial Cells: Apical & Basal Sides 7:06
Glandular Epithelial Tissue Forms Endocrine & Exocrine Glands 8:20
Review 9:16
Credits 9:54

***

Want to find Crash Course elsewhere on the internet?

[yourmomjay]

Crash Course should have PDFs for "end of lesson" tests. That would be another great way to keep all this beautiful info inside mah head.

[sudharsanvj]

Notes:
3.Epithelial tissues

Two kinds: PROPER/PRIMARY EPITHELIUM (covers & lines the outer and inner body) and GLANDULAR EPITHELIUM (forms the glands and secretes hormones & other substances).
Epithelial tissues are Avascular (not associated with or supplied by blood vessels). They instead rely on the blood supply to the Connective tissues around them for the materials they need.
Criteria for classification of Epithelial cells: Shape of the individual cells and the number of layers that they form in.
THREE BASIC SHAPES:
SQUAMOUS cells (flattened shape and flat nucleus, fast absorption and diffusion, making thin membranes).
CUBOIDAL cells (spherical nucleus, cuboidal cell shape, absorb nutrients and produce secretions like sweat).
COLUMNAR cells (Elliptical nucleus, column shaped cell with hexagonal cross-section, tall, thick & cushion underlying tissues, absorb nutrients and produce secretions).
Usually the form (shape and layering) of the epithelial cell is related to it's function/purpose.
Producing cells take a lot of time, energy and raw materials. So in places where we lose a lot of cells (like outer skin or mouth) we have squamous cells because they are biologically cheaper.
TYPES OF LAYERING:
SIMPLE EPITHELIUM: one layer of cells.
STRATIFIED: Multiple layers set up on top of each other, like bricks.
PSEUDOSTRATIFIED: Mostly one layer but formed with cells of different shapes and sizes. The cells nuclei can be at a lot of different levels (i.e they don't lie on the same plane- different heights). So it looks like multi layered.
NAMING OF A EPITHELIAL TISSUE:
First name: Number of layers.
Last name: Shape of its cells.
Example: Simple squamous epithelium.
All Epithelial cells are POLAR i.e they have distinct sides.
The boundaries of many of these cells are 'Selectively Permeable'(Allowing for some level of absorption, filtration and excretion of substances). Example: tissues lining the small intestine allows absorption of nutrients through diffusion and active transport. This is what makes possible all interaction we have with the world since Epithelial cells line both the insides and outside of the body (U Tube) .
GLANDULAR EPITHELIUM forms two different types of glands: ENDOCRINE glands (secrete hormones directly into the blood stream or to nearby cells) and EXOCRINE glands (secrete their juices into tubes or ducts that lead to the outside of the body.

[Romanticoutlaw]

this might sound a little silly, but I'm going through a rough emotional time right now and watching cold hard science interspersed with cheesy jokes really helps me move my focus away from harmful things. Thank you, Hank.

[katan.]

I should give him my tuition money instead! he's so helpful

[maeve_zahra]

My teacher keep trying to explain this to class for a month and while I get the basic, I don't get the whole idea but it only took you ten minute to make me understand wow, Hank... thank you so much!

[urishima]

He looked so pleased with himself when he made that Youtube joke... I wanna give him a cookie.

[kariwithlove]

I pause it every 5 seconds to take notes (because yes you do talk very fast) but I already learned so much more than listening to my teacher blab on for 3 hours. Thank you so much!!!!

[CrazycruxGaming]

weird thought, but i absolutely LOVE the art style in his diagrams. it is very sleek, stylishly simple, and easy to remember.

[ShinoAburame]

I'm a giant science nerd, so these science-based crash course series are absolutely outstanding entertainment! Thanks for making them, and I urge you to continue with more fields of science, like Physics!

[crashcourse]

Pssst... we made flashcards to help you review the content in this episode! Find them on the free Crash Course App!

[suchizinzuwadia]

that "you tube" joke was great.

[jacquelinefee]

I'm taking biology this semester and it has not been a walk in the park to say the least. But, thanks to all your video's (including SciShow), I'm passing the class with a B! I, as well as everyone, really appreciate all the work you and your staff do! Thank you :)

[TheSmileycup]

God bless you guys! Seriously! I'm a freshman nursing major and these videos are helping me understand my A&P material. thank you, thank you, thank you

[jessicapolito]

I totally forgot how incredibly exhausting, yet entertaining and helpful, your online crash courses were. This channel was able to help me pass several of my science and health classes in middle school and high school. Now your videos are helping me understand anatomy and physiology, so thank you. I was only able to watch 3 videos in a row today, but I am going to try to watch the rest of this crash course throughout the next several days.

[emmad.]

THANK YOU FOR CLOSED CAPTIONING THESE CRASH VIDEOS :D

[Xenro]

I'm not remotely interested in anatomy or physiology, but when it's taught by Hank, I just have to watch it because it's so epic :D

[GC]

Did any balloons get popped during takes for that scene?

[doulacandice]

These videos are gold. Nursing student here, they help us so much.

[DontMockMySmock]

Hank putting his fingers into an "invagination" made me chuckle.  I am a twelve-year-old apparently.

[BreBreLalala]

Okay, so I just want to say that years ago I wanted to learn all of this and go to uni. I did some reading and my brain almost exploded, so I came to youtube and still, couldn't wrap my head around ANYTHING. I never pursued any science-based career.
Fast forward to now, I am ENJOYING watching all of these videos, I am glued to the screen and loving it! I am looking forward to applying to study a science degree, so THANK YOU! So so grateful for your knowledge, fun presence and interesting analogies haha! Theeee bestt!