Tissue part 4
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This document discusses the specializations of epithelial cells. It describes the three main domains - apical, basal, and lateral. The apical domain contains structures like cilia and enzymes. The basal domain attaches to the basement membrane and contains infoldings. The basement membrane is made of collagen and laminin. Junctions between cells include tight junctions, adherens junctions, and desmosomes. Gap junctions allow cell-to-cell communication. Epithelial cell specializations allow functions like barrier formation, regeneration, and transport of fluids.
Tissue part 4
- 3. SPECIALIZATIONS OF EPITHELIAL CELLS • BASAL • APICAL • LATERAL
- 4. APICAL DOMAIN • STRUCTURAL MODIFICATION – CILIA – MICROVILLI – STEROCILIA • SPECIFIC ENZYMES (HYDROLASES) • ION CHANNELS • CARRIER PROTEINS
- 5. BASAL DOMAIN • BASEMENT MEMBRANE • JUNCTIONS b/w cells & extra cellular structures • INFOLDINGS OF PLASMA MEMBRANE
- 6. BASEMENT MEMBRANE • SHEET LIKE EXTRACELLULAR MATERIAL • PAS +ve • BASAL LAMINA & RETICULAR LAMINA • TWO BASAL LAMINA
- 8. BASAL LAMINA • E/M 20-30nm • BASAL LAMINA A LAMINA DENSA B/W 2 LAMINA LUCIDA/ RARA • COMPONENTS SECRETED BY EPITHELIAL CELLS – TYPE IV COLLAGEN, – GLYCOPROTEINS – PROTEOGLYCAN – ANCHORING FIBRILS (VII) BL & RL
- 9. RETICULAR LAMINA • RETICULAR FIBERS TYPE III • UNDER LYING CONNECTIVE TISSUE • COARSE ALL DIRECTIONS
- 10. FUNCTIONS • STRUCTURAL – attachment to underlying structures • BARRIER & FILTRATION – Regulating movements • REGENERATION • Information for cell to cell interaction • CELL POLIFERATION & DIFF. – Binding & concentrating growth factor
- 11. JUNCTIONS B/W CELLS & EXTRACELLULAR STRUCTURES FOCAL ADHESION HEMIDESMOSOMES
- 12. FOCAL ADHESION • ACTIN OF CYTOSKELETON into BASEMENT MEMBRANE • THRU TRANSMEMBRANE PROTEIN INTEGRIN
- 13. HEMIDESMOSOMES • EPITHLIA subject to ABRASION SHEARING • CORNEA , SKIN, MUCOSA • HALF DESMOSOMES • ATTACHMENT PLAQUE • INTERMEDIATE FILAMENT INTO BASEMENT MEMBRANE • PROTEIN INTEGRIN ( CADHERIN) • EXTRACELLUALR COMPONENT OF INTEGRIN INTERACTS WITH LAMININ & TYPE IV COLLAGEN OF BASAL LAMINA
- 14. HEMIDESMOSOMES •
- 15. INFOLDINGS OF BASAL PLASMA MEMBRANE • FLUID TRANSPORTING CELLS • PCT , DCT, STRIATED DUCTS • MITOCHONDRIA
- 16. LATERAL DOMAINS • APPOSED LATERAL DOMAINS • UNIQUE PROTEINS & LIPIDS • JUNCTIONAL COMPLEX OCCLUDING JUNCTIONS ANCHORING JUNCTIONS COMMUNICATING JUNCTIONS • FOLDS / PROCESSES
- 17. JUNCTIONAL COMPLEX • OCCLUDING JUNCTIONS ZONULA OCLUDENS • ANCHORING JUNCTIONS ZONULA ADHERENS MACULA ADHERENCE BASAL focal adhesion, hemidesmosome
- 18. TIGHT JUNCTIONS ZONULA OCCLUDENS • APICAL BAND • SERIES OF FOCAL ADHESION • OCClUDENS--- ZO---- ACTIN • BARRIER luminal &intercellular space • INTEGRITY OF DOMAINS • IMPERMEABILITY number of fusions • LIMITED RESISTANCE TO MECHANICAL STRESS
- 20. ANCHORING JUNCTIONS ZONULA ADHERENCE • BELOW OCCLUDENS • BAND reinforcing ZONULA OCCLUDENS • 20-30nm space • TRANSMEMBRANE PROTEIN CADHERIN- CATENIN-ACTIN (actinin,vinculin) • MECHANICAL STABILITY • FACIA ADHERENCE SHEET LIKE, CELLS OTHER THAN EPITHELIA
- 22. DESMOSOMES • MACULA ADHERENCE • STRONG ATTACHMENT • SPOT JUNCTIONS • INTERCELLULAR SPACE 30nm • TRANS MEMBRANE PROTEIN CADHERIN FAMILY (desmoglein & collin) • ATTACHMENT PLAQUE (desmoplakin) • INTERMEDIATE FILAMENT
- 24. GAP JUNCTION NEXUS • COMMUNICATING JUNCTIONS • VARIOUS TISSUES (coordinated) – EPITHELIUM, SMOOTH & CARDIAC MUSCLE, NERVOUS • EXCHANGE(ions,regulatory mol.& small metabolite) • TWO CONNEXONS • Connexins 6 (dumbell) • HYDROPHILIC PORE 2nm