Epithelium & Glands II Flashcards
Junctional complexes
occluding - tight - zonula occludes
anchoring - adhering(zonula adherens) & desmosomes(macula adherens)
Communicating - Gap
Zonula Occludens
Tight Junctions
localized sealing of mbrn of adjacent cells
anastomosing strands(zipping)
Claudins & Occluding
interaction with actin cytoskeleton via ZO-1, ZO-2, ZO-3
JAM
associated with ZO-1 & claudin
Present in endothelial cells; mediates interactions btw cells and monocyte adhesions
ZO-1
Important link in transduction of signals from all transmembrane proteins; interacts with actin filaments; has tumor-suppressor action
ZO-2
Required in the epidermal growth factor-receptor signaling mech.
ZO-3
interacts with ZO-1, occluding, and actin filaments of the cytoskeleton
Claudin
forms backbone of zonula occludes strands; forms and regulates aqueous channels used for paracellular diffusion
Susceptable to enterotoxins: mona zuna’s revenge (leaking… :-( )
Occludin
is present in most occluding junctions; maintains barrier btwn apical and lateral cell surface
Susceptable to enterotoxins: mona zuna’s revenge (leaking… :-( )
Zonula Adherens
Calcium dependent E-Cadherin proteins
Anchoring - lateral aspect, just below tight
15-20nm gap
Interact with actin
Macula Adherens
Demosomes
Lateral, localized, spot adhesion - 30 nm gap
Present: macula(spot)
beneath zonula adherens
Transmbrn pro: desmocollin & Desmoglein (Ca2+ dependent cadherins)
Intercellular plaque - Plakoglobins & Desmoplakins
Interact w/intermediate filaments - collogen
Gap Junctions
Communication
Location: epithelium, Smooth & cardiac Muscle, Nerve
Coordinate cellular activity
6 connexin to make a connexon
Lateral Interdigitations
Infoldings(plicae) of cytoplasm
Fluid & electrologist transport
Location: gallbladder, sm. intestine
Na+/K+ ATPase
Focal Adhesion
Actin filament Integrin to fibronectin Anchoring Junction Link btw cytoskeleton actin and ECM cell migration
Hemidesosome
Intermediate filament
BP230, alpha6beta4 integrin, typeXVII collagen, laminin-332
cell to ECM junction
1/2 a desmosome
Dx: bullous pemphigoid; blister, antibodies directed against BP230 & Type XVII collagen
Basal Infoldings
increase SA transport proteins and channels Location: kidney tubule, striated ducts of exocrine glands. Vertical mitochondria. LM - striated appearance
Basal Lamina
TEM - overlying epithelial cells and underlying connective tissue
“external lamina”
Composition: laminins, type IV collagen, Proteoglycans & glycoproteins.
2 layers: Lamina lucida (artifact). Lamina densa (electron dense)
Podocyte
cells in the Bowman’s capsule in the kidneys that wrap around capillaries of the glomerulus
Exocrine Glands
Merocrine - morn bound vesicles
Apocrine - bleb, lactating mammary
Holocrine - apoptosis, sebaceous
Endocrine Gland
secrete product (hormones) into the connective tissue
Paracrine - nearby effect
Autocrine - same cell
Simple Tubular
Lg. intestine, colon
straight tube
goblet cells
simple coiled tubular
Skin: eccrine sweat gland
coiled tube, secretory portion deep in the dermis
simple branched tubular
Stomach: pylorus mucus. Uterus: endometrial.
wide secretory portion
viscous mucous
simple acinar
Urethra: paraurethral & periurethral
outputting of the transitional epithelium
single layer of secretory cells
“change purse”
Branched acinar
stomach: mucus of cardia.
Skin: sebaceous
short, single-duct portion opens directly into the lumen
Compound tubular
Duodenum: submucosal, Brunner.
coiled portions deep in submucosa
Compound Acinar
Pancreas: exocrine.
alveolar-shaped
formed by pyramid-shaped serous-secreting cells
Compound tubuloacinar
submandibular salivar gland
both mucous branded tube & serous branded acinar units. serous end-caps (demilunes)
Serous glands
watery - poor to no glycosylation round/oval nuclei zymogen granules - eosinophilic basophilic perinuclear cytoplasm - rER ex. pancreatic acinus, serous compound acinar gland
Mucus Gland
viscous/slimy - extensive glycosylation
flattened/compressed nuclei
PAS positive
Mucinogen granules - poorly preserve, empty space with H&E
Mixed Gland
Mucous & serous ex. submandibular gland compound tubuloacinar gland serous demilune - half moon cap striated duct
