Epithelial Specializations and Exocrine Glands Flashcards
Domains of epithelial cells
apical, lateral and basal
Domain functions
Responsible for establishment and maintenance of cell polarity
Micro-villi - Structure
Small (1 millimeter) finger like extensions of apical membrane.
Project into lumen.
Possess actin filaments.
Anchored into terminal web.
Micro-villi - Function
increase cell surface area
Micro-villi - example location
intestinial absorptive cells
Setreocillia - Structure
NON-MOTILE microvilli. Long (10-25 millimeter) finger like extensions of apical membrane. Project into lumen. Possess actin filaments. Anchored into terminal web.
Cilia - Structure
Hair-like projections. Large 0.2 um diameter/10um length MOTILE axoneme 9 + 2 arrangement
axoneme
microtubles core (tubulin dimers)
Cilia - Function
W/ Dynein, move substances across surface of epithelial layer
Flagella
Microtubular core in Spermatoza
Cilia Disorders
Primary ciliary dyskinsiea
Kartageners syndrome
Youngs syndrome
Primary ciliary dyskinseia
immotile cilia syndrome
Kartageners syndrome
cilia lack dynein
Youngs syndrome
cilia have malformed radial spokes and dynein arms
Lateral Domain - Structural components
cell to cell junctions
Lateral Domain - Function
attachment
exchange of small molecules
regulation of the movement of materials across epithelial layer (apical basal)
Lateral Membrane - Structure
terminal bars
terminal bars
junctional complexes (visible in light microscope)
Junctions - types
Tight Junction
Adhering Junction
Desmosome
Tight Junction a.k.a
Zonula Occludens
Adhering Junction a.k.a
Zonula Adherens
Desmosome a.k.a
Macula Adherens
Tight Junction - Structure
close to apical surface
belt-like structure encircle circumference
system of membrane folds
mediated by occludin and claudin/cadherins
Tight Junction - Function
- Prevent free flow water soluble molecules between cells
- Compartmentalize integral membrane proteins into apical and basolateral domains
Adhering Junction - Structure
Adjacent and basal to zonula occuldens
belt-like structure encircle circumference
Uniform distance between adjacent membrances
Mediated by cadherins/catenins
Adhering Junction - Function
cell adhesion
link actin cytoskeleton of adjacent cells
Desmosomes - Structure
basal to belt junctions Distributed randomly along domain Attachment Plaques (Paired thickened membrane region) Dense material in intercellular space Associated with intermediate filaments of cytokeratin
Desmosomes - Function
Spot Adhesions - strong to disperse shearing forces on cell membrane
