Epithelial Tissues

Question 1

Location

Answer 1

cover body surfaces, line cavities of cardiovascular, digestive, genitourinary and respiratory systems and form secretory glands)

Question 2

Polarity (2 Types)

Answer 2

• 1- Apical- basal Polarity
  
  • 3 domains… apical/mucosal (surface), lateral (cell-cell interactions) AND basal/serosal (contacts basement membrane)
  • Collectively the basal and lateral membranes are called “basolateral membrane”
• 2- Planar Polarity
  
  • Asymmetry w/in sheets of cells
  • Coordination of polarization of cells or structures in plane of tissue

Question 3

Glycocalyx

Answer 3

sugar coat (carbs) + glycoproteins and glycolipids; extends 300 nm from cell surface; intestinal tract

- Hydration
- Lubrication
- Restrict movement of molecules based on charge/size
- Signaling and metabolism
- Protection from Pathogens
- Mechanotransduction

Question 4

Apical Structures (6)

Answer 4

Glycocalyx
Mucus Layer 
Microplicae 
Microvillae
Stereocilia
Cilia (motile, non-motile and nodal)

Question 5

Microplicae

Answer 5

• ridge-like folds of plasma membrane (straight, curved or branching); coated w/ glycocalyx; loosely organized acton cytoskeleton; lining the hard palate, cornea, fallopian tubes, and the ureters, bladder, and upper urethra
  
  • Function not known? Maybe protect apical surface from abrasion

Question 6

Microvilli v Stereocilia

Answer 6

• Microvilli - apical membrane extensions made of actin filament bundles anchored in terminal web; enterocytes of SI and proximal tubule cells of kidney
  
  • Inc SA
  • Mechano-transduction
  • Sensory perception
• Stereocilia - longer than microvilli w/ core of actin filaments too; cells lining epididymis and hair cells in inner ear
  
  • Sound transduction
  • Inc SA for fluid reabsorption in epididymis and vas deferens

Question 7

Types of Cilia (3)

Answer 7

• Motile Cilia - whip-like projections of microtubules; anchored to basal bodies in cytoplasm; 9 + 2 organization; trachea, brain ventricles, oviducts, embryonic node
  
  • Promote movement of fluid, substances and cells
• Primary or Non-Motile Cilia - usually 9+0 organization of microtubule pairs; lack central microtubule and dynein; usually one projecting from surface of most mammalian cells
  
  • Chem or mechanical sensors
  • Translate the signals into intracellular responses
  • ***Notch/Gli Signaling (embryology)
• Nodal Cilia - 9+0 microtubule architecture; ability to move in propeller-like fashion; cells of primitive node
  
  • L/R asymmetry in embryogenesis - generate leftward movement

Question 8

Lateral Junctions (5)

Answer 8

Tight Junction 
Adherens Junction 
Desmosomes
Gap Junction 
Hemi-desmosomes

Question 9

Basement Membrane

Answer 9

• Acellular
• Functions- support, barrier, filter movement of cells, scaffold for regeneration
  
  • Collagen IV provides tensile strength
  • Laminin is the organizer of the basal lamina
• Transmembrane - hemidesmosomes
  
  • Integrins link cytosleleton to ECM
• Basal lamina components- laminins and fibronectin