Where are three places you can find epithelia
- external surfaces
- luminal surfaces: GI tract, respiratory tract, endothelium in blood vessels
- glands:
What are 4 major characteristic of epithelia
- No (little) ECM
- free apical surface
- Avascular (diffusion)
- Has basal lamina
What are types of epithelium
- Simple; 1 layer
- Stratified: 2 layers
1. Squamous: flat
2. cuboidal: cubed
3. columnar: taller
Endothelium and mesothelium are ___ ____epithelium
simple squamous- lines blood vessels; all serous membranes- lines body cavities ; peritonuem etc
Simple ____
cuboidal; line ducts
Skin is ____squamous
stratified; great barrier for protection
Psudo _____columnar is found along:
stratified; trachea and bronchi; not everything goes to surface
_____epithelium is generally for:
urinary tract; changes depending on how it is stretched.
Shape is always based on ____cell not basal
luminal surface
Eosin stains ____
dark; collagen fibers
Stratified squamous lines:
esophagus, anal canal, distal vagina and urethra
If every single cell is reaching the BM then it is a ____stratified epithelium
psuedo; tends to be found along airways, so there will be cilia on apical surface
Microvilli inc ___area
surface; specialization for absorption
What are stereocilia
just extra long microvilli; not cilia
What are cilia
much longer than microvilli; more than just a dark line. Can see microtubules
What is the difference between looking at microvilli and cilia
- In cilia in EM you can see cytoskeletal components inside
2. Much longer; it looks more hairy instead of a dark line
Cilia has microtubules that consist of _____ and a basal body that consists of ____
axoneme; centrioles (9 triplets and no central microtubule)
Flagella are in ____and cillia are found in _____tract
sperm; respiratory; anything that helps make it move.
What are lateral surface junctional complexes
- Occluding (tight junctions): near apical border; interactions between proteins bet proteins of adjacent cells. form in complexes that form lines.
- Desmosomes (Adherens):
- Gap junction: communicating, that creates a pore that allows small molecules and signaling molecules to travel through. Occur in clusters.
WHat is Pemphigus
autoimmune disease that attacks desmosomes
What does basal lamina refer to
Seen by EM, refers to lamina rara (lamina lucida) and lamina densa
- Produced by epithelial cells
- Reticular fibers formed by CT
What does basement membrane include
includes basal lamina and reticular fibers
What anchor cell?
- Focal adhesions; Interact with actin cytoskeletons
- Hemidesmosomes: interact with intermediate filaments
- They both use INTEGRIN transmembrane proteins
Which junctions connect cell-cell and use cadherin protein
- Zonula adherens-use actin
2. Desmosomes- intermediate filaments
What are glands
Specialized epithelium for secretion.
What are the types of glands
- Exocrine: Secrete into lumen, ducts, or surfaces
- Endocrine: glands secrete into bloodstream
- Paracrin: glands secrete into interstitium.
What are the types of exocrine glands
- Merocrine: Secretory vesicles containing product fuse with apical membrane; Most sustainable
- Apocrine: apical membrane buds off with product inside; depletes membrane
- Holocrine: Product is released when cell undergoes apoptosis
Secretory products
Serous secretion: watery, protein rich
Mucous secretion: viscous, carbohydrate rich
What is a goblet cell
find along airways and digest tract. secrete mucous that lubricate lining of lumen. Produce a mucous secretion. These are the simplest cells
What do you have with a multicellular gland
- All epithelial derived cells that invaginate in CT that specialize into duct or gland.
- Name glands based on duct shape.
What are the two types of ducts
- Simple: ducts are unbranched
- Compound: Ducts are branched
- Can be tubular or alveolar-describe shape
