Epithelium & Epithelial Glands Flashcards
What are the 7 main Characteristics of Epithelium?
- Line body surface cavities
- except joint cavities
-
Avascular
- no direct blood supply
-
Polar
- apical, basal, lateral sides
- Little extracellularmatrix
- Located on basal lamina
- High capacity for renewal
-
Many functions
- protection from abrasion
- secretion
- absorption
- restriction of nutrient flow
- contractility (myoepithelial cells)
- sensation (neuroepithelial cells)
What are the 5 surface modifications?*
- Striated/brush border (microvilli)
- Stereocilia (long microvilli)
- Cilia
- Keratin or Parakeratin
- Glycocalyx
What type of epithelium is this?
Simple squamous epithelium
- Flattened
- Single layer
- Endothelium = lining a blood/lymph vessel
- Mesothelium = lining body cavity
What type of epithelium is this?
Simple cuboidal epithelium
- Square cells
- Single layer
- Round Nuclei = centrally located
- little cytoplasm
What type of epithelium is this?
Simple columnar epithelium
- Rectangular cells
- Single layer
- Nuclei = oval, towards BL
NOTE: May have immune cells migrating through
What type of epithelium is this?
Stratified squamous epithelium
- Top layer = flattened
- Multiple layers of cells
- Surface modifications:
- Non-keratinized (IMAGE)
- Keratinized
- Parakeratinized
What type of epithelium is this?
Stratified Squamous Keratinized Epithelium
- Highly keratinized = THICK skin
- Moderately keratinized = THIN skin
- cells lost nuclei
Parakeratin
- Looks like keratin w/ nuclei in the top layer
- __usually in mouth (gingiva)
What is this?
Squamous Cell Carcinoma
- Keratinization = characteristic of this
- dead cells swirled together
What are these 2 types of epithelium?
Stratified cuboidal (LEFT) and columnar (RIGHT)
- Both found in larger ducts of different glands
What type of epithelium is this?
Pseudostratified Columnar Epithelium w/ Goblet Cells & Cilia
-
All cells = sit on BL
- Not all cells = reach surface
- Cilia + Goblet = respiratory epithelium
What type of epithelium is this?
Pseudostratified Columar Epithelium w/ Stereocilia
- Long microvilli
- Clump like paintbrush
-
Contain microfilaments of actin
- NOT true cilia
What type of epithelium is this?
Transitional epithelium (aka Urothelium)
- Balloon/Umbrella cells on surface
- Type of pseudostratified epithelium
- all cells = touch BL
- not all cells = touch surface
- Discoidal vesicles (another type)
- membrnae infoldings cut = look like vesicles
- actually an artifact
- allow for expansion of the transitional epithelium when bladder is full
- membrnae infoldings cut = look like vesicles
What is this structure?
Microvilli
- Fingerlike projections
- Appear as striated or brush border in LM
- dense line, but not separate structures
-
Core = Microfilaments (actin)
- run perpendicularly underneath microvilli (terminal web)
- cytokeratin = deep in terminal web
- Acti binding + motor proteins (myosin) present
What is this structure?
Cilia
-
Core = microtubules
- 9 + 2 arrangements of tubulin
- basal bodies = 9 triplets of microtubules
- Dense line deep to cilia = basal bodies (IMAGE)
What are the 4 Lateral Surface Specializations?
- Zonula occludens
- Zonula adherens
- Macula adherens
- Zonula communicantes (Gap Junction)
What are the 4 Basal Surface Specializations?
- Basal lamina
- Basement membrane (can see on LM)
- basal lamina & reticular lamina
- Fused basal lamina
- Hemidesmosome
- Focal contact
What type of epithelium is this?
Infiltrating squamous cell
carcinoma
What basal surface specialization is this?
Basement membrane - 2 fused basal lamina
- Fused basal lamina
- lamina rara
- Fused lamina densa
- lamina rara
- Ex: kidney epitheial cells
What is the difference btw the images?
Thickening of capillary basement membrane
- glomerulonephritis (LEFT)
- pink = protein in basement membrane
- normal glomerulus (RIGHT)
Exocrine v Endocrine
- Glands are epithelial in origin
- formed by invagination of surface epithelium
-
EXOCRINE
- retain connection to the surface (duct)
-
ENDOCRINE
- loose connection to the surface
- secrete into the blood
How to Classify Exocrine Glands?
-
How many cells
- single or multi cell
- unicellular = goblet
- multicellular = exocrine or glandular epithelium
- single or multi cell
-
What they secrete
- serous (protein)
- mucous
- mixed
- mucous w/ serous demilumes
-
Tubular v acinar/alveolar
- tubular = more linear
- acinar = ball shaped
- Simple v branched
- Coiled v straight
- Simple v compound
- simple = acinaer
- multi = tubuloalveolar glands
What are the 2 types of Glandular Epithelium?
-
Mucous cells
- Flattened nuclei
- Cell looks washed out
- Secretes mucous
-
Serous cells
- Rounded nuclei
- Cell stains well
- Secretes protein (granules)
What type of epithelium is this?
- Mucous cells (right arrows)
- Serous demilunes (left arrows)
What are the 3 types of exocrine secretion?
-
Merocrine
- exocytosis
- ex: exocrine pancrea
-
Apocine
- piece of cell pinches off
- ex: milk proteins
-
Holocrine
- whole cell becomes secretion
- ex: sebaceous glands (unicellular)
Name the 5 Epithelially‐derived Tumors
- Papilloma – non‐malignant tumor of epithelium
- Carcinoma – malignant tumor of epithelium
- Adenoma – non‐malignant tumor of glandular epithelium
- Adenocarcinoma – malignant tumor of glandular epithelium
-
Apudoma – tumor of APUD cells (Amine Precursor Uptake and Decarboxylation) AKA enteroendocrine cells;
- tumor can be benign or malignant
