Epithelial Tissue Flashcards
What are the different types of epithelia?
Surface (lining) epithelia
Glandular Epithelia
Germinal Epithelia
What is the function of surface (lining) epithelia?
Form external surface - body and many organs
Form internal lining of hollow tubes - ducts, vessels, tracts
Form internal lining of body cavities
Specialized surface epithelia contain touch receptors and may contain receptors for senses
What is the function of glandular epithelia?
Secrete glandular products exocrine and endocrine
What is the function of germinal epithelia?
Generate gametes and foster their maturation/development (ovaries, testes only)
What epithelia are highly active both metabolically and synthetically?
Glandular and germinal
All epithelia have high ___
Turnover
Where do most tumors derive from?
Epithelial Tissue
What are 3 benign epithelial tumors?
- Adenomas
- Papillomas
- Polyps
What are defining characteristics of epithelia? x 7
Highly cellular - high cells to ECM ratio
Basement Membrane (BM)
Polarity: Apical, Lateral, and Basal Domains
Cell Junctions
Avascular
Intermediate Filaments made of keratin
Often have apical surface modifications - cilia
What is the basement membrane of epithelium?
Interface between epithelium and underlying connective tissue. Most of ECM of epithelia
What are the functions of the basement membrane?
Provides structural support
Physical Barrier
Metabolite diffusion
Helps regulates epithelial growth and differentiation
What are three layers of the basement membrane?
Lamina Lucida
Lamina Densa
Lamina fibroreticularis
What are the characteristics of the lamina lucida?
Multi-adhesive glycoproteins - laminins
Electron lucent
What are the characteristics of lamina dense?
Collagen IV - mesh forming collagen, abundant in basement membrane
GAGs
Electron dense
What are the characteristics of lamina fibroreticularis?
Collagen III fibrils - reticular fibers
Collagen VII - anchoring fibrils. Helps anchor lamina densa to underlying connective tissue
Collagen I - small amounts
What is the basal lamina? What is its function?
Lamina lucida and lamina densa only
Flexible support for overlying epithelium. Anchors cells to basement membrane. Molecular filter
How does the lamina lucida stain?
Laminins - PAS positie
How does the lamina densa stain?
Collagen IV - IHC and PAS positive
Sulfated GAGs - metachromatic and PAS+
How does the lamina fibroreticularis stain?
Collagen III - Argyrophilic and PAS positive
Collagen VII
Collagen I - weakly acidophilic
What are simple epithelia?
1 layer of cells
What are stratified epithelia?
2 or more cell layers
What is pseudostratified epithelia?
Have 1 layer but looks like more than 1 layer
What are the functions and locations of simple squamous epithelia?
Functions - Diffusion, form linings, and secrete serous fluid for lubrication
Locations: Lining body cavities, vessels, alveoli, Bowman’s capsules, and heart chambers
What is the structure and what are the functions and locations of simple cuboidal cells?
Square - as tall as it is wide
Functions - absorption, secretion, and conduits (forms wall of small ducts)
Locations - Ducts in exocrine glands, renal tubes, thyroid follicles