Histology - Epithelium Flashcards
Extracellular matrix layer between epithelial cells and underlying CT. Carbohydrate base.
Basement membrane
bands encircling the cell, linking adjaent cells together. Resists mechanical separation of cells.
zonula adherens
integrin used as adhesive moleculelinking basal lamina to cytoskeleton.
Cell-Matrix Junctions
do not normally undergo mitosis, however retains ability if organ damaged or needs increase (ex, hepatocytes).
Stable epithelium
bacteria in GI tract that attacks tight junctions and causes ulcers.
Helicobacter pylori
Adheren Junctions (Zonula adherens)
E-cadherin (grey dots at TEM) inserted into intracellular space and fuse together and linked to Actin filaments. Zonula (Belt) all the way around the cell. Resist mechanical separation and maintains sheet-like structure. Found in Epithelium and Cardiac muscles
Microvilli
Short projections of the apical membrane and cytoplasm of lumen w/ associated Glycocalyx. Composed of plasma membrane surrounding Actin Filament Core which is anchored to a terminal web (actin). Forms a brush border (flat top haircut).
Occludin and Claudins
Claudins join in the intercellular space to form Junctional Strands
actin filmamentous core, cross linked to plasma membrane and other actin binding proteins. Anchored to Terminal Web (TW) (also actin).
Microvilli core skeleton
only a few, no mitosis (adult), eg, cells in core of lens, hair cells, inner ear.
Permananet Epithelium
Uncontrolled proliferation of cells (failure of normal regulatory mechanisms)
Neoplasia
3-4 longer than MV, less ‘orderly’. Specialized to move substances along a surface.
Cilia
steady state renewable, replace cells that are ocntinuously lost, with rpesent stem cells. Proliferation is highly regulated (ex: epidermis, epithelium of GI tract, respiratory system, urogential systems)
Labile epithelium
No CAMs, have transmembrane connexons. Aid in cell-cell communication.
Gap junctions
tight junction, barrier to paracellular transport.
Zonula Occuldens
Lateral Folds
Increases surface area through interdigitation of plasma membrane of adjacent cells, aiding in Fluid and Electrolyte transportation via Transcellular pathway.
Focal Adhesion
Integrin proteins linked to basal lamina outside cell and Actin Filaments inside cell. Aids in adhesion and mechanosensitivity.
Adaptor Proteins
Supress proliferation of epithelial cells.
Transcellular transport
Transcellular transportExchange of substances to/from lumen and CT by passing through an epithelial cell. Active process.
associated with aubdant mitochondria that increase surface area for active ion transport.
Basal folds
BL (basal lamina) + RL (reticular lamina) (at TEM level)
BM (at light level)
a carcinoma featuring microscopic glandular-related tissue cytology, tissue architecture, and/or gland-related molecular products, e.g., mucin.
Adenocarcinoma
interact with desmosomes (cell-cell adhesion) and hemidesmosomes (cell-matrix adhesion) via adapter proteins.
Intermediate filaments
problem with adhering type junctions, cells pull apart and space fills with fluid.
blistering
Covers, lines, secretes, absorbs
Epithelium
a cell junction whose cytoplasmic face is linked to the actin cytoskeleton.
Adherens junctions
influecne lots of process that occur within cell, one is suppress proliferation (contact inhibition).
adaptor molecules
Epithelial cells adjacent to the wound site divide, giving rise to new epithelial cells. The new epithelial cells detach and migrate laterally along the remnants of the basal lamina that are still present.
Wound healing
a belt like intercellular junction located between adjacent lateral domains immediately “above” the adherens junction. No CAMs, connected by transmembrane proteins. Help define functional domains (apical-basolateral) - establishing polarity and limit paracellular transport.
tight junction
Wound repair
Loss of adaptor proteins causes epithelial cellad and stem cells adjacent ot wound to proliferate. New epithelial cells detach and migrate along basement membrane.
Cilia
Long projections used for movement of substances and cells, synchronized movement. Less organized, 9+2 arrangement of microtubules.
Cell-to-Matrix Adherents
Hemidesmosomes, Focal Adhesions
Apical specilization that establishes extracellular microenvironments at membrane surface. Functions: metabolism, cell regocnition, receptor sites etc. Composed of: glycoproteins and glycolipids.
Glycocalyx
orderly series of 3 junctions, tight junction, adherens junction (ZA), desmosome (D) - terminal bar at light level.
Junctional complex (@ TEM)
Blisters
Strong abrasionand sheering disrupts Focal Adhesions causing separation of epithelial cells from connective tissue and fluid accumulation.
Apical Domain
Directly Contacts Luminal Contents or External Area
is an assembly of six proteins that can be a part of a gap junction channel between the cytoplasm of two adjacent cells. Two come together to complete intercellular gap junction channel.
connexon
a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both.
adenoma
Interdigitations of plasma membrane of adjacent cell lateral comains located below levelk of the junctional complex that increases surface area for interlocking cells and fluid and electrolyte transport via transcellular pathway.
Lateral Folds
Apical Folds
Increase surface area for mainly absorption and secretion between lumen/external environment
Integrins
transmembrane receptors that are the bridges for cell-cell and cell-extracellular matrix (ECM) interactions. When triggered, integrins in turn trigger chemical pathways to the interior (signal transduction)
Hemidesmosomes
Integrin proteins attached to Basal lamina outside cell and attachment plaque inside cell. Keratin intermediate filaments strengthen them by adhering to attachment plaque. Resists abrasion, sheering, and tearing forces between Epithelial Cells and Basal Lamina. Strong attachment between epithelial cell and basal lamina.
Special arrangement of microtubules. 9 outer doublets, and 2 central singlets. Abbreviated “9+2”. Anchored into the basal body.
Cilia core
Cell-to-Cell Adherents
Adheren Junctions (Zonula adherens), Desmosome (Macula adheren)
proteins located on the cell surface involved in binding with other cells or with the extracellular matrix (ECM) in the process called cell adhesion.
Cell adhesion molecules (CAMs)
a type of cancer that develops from epithelial cells.
carcinoma
Weave back and forth through each cell’s plasma membrane several times
transmembrane proteins
9 triplets
Basal body MT composition
occludin and claudins that weave through each cell’s plasma membrane and extend into ICS.
Transmembrane proteins
rows of transmembrane proteins from adjacent cells that appear as ridges or stitches that act as a barrier to paracellular transport pathway.
Junctional strands
a type of connective tissue that has a network of reticular fibers, made of type III collagen and only in this lamina are they dominant. Have anchoring fibers and plaques (loops). Thickness varies with frictional force applied to overlying Epi.
reticular lamina
directly contacts the luminal contecnts or external environment. Site of absorption and secretion.
Apical domain
types of large macromolecular assemblies through which both mechanical force and regulatory signals are transmitted that serve as the mechanical linkages to the ECM, at sites of integrin binding and clustering.
focal adhesions
Desmosome (Macula adheren)
Desmosome Cadherin (CAM) insert into intercellular space and overlap each other, inserted into attachment plaque inside cell. Strengthened by keratin intermediate filaments.
localized spot-like adhesions randomly arranged on the lateral sides of plasma membranes. help to resist shearing forces and are found in simple and stratified squamous epithelium. ‘velcro dots’
desmosome
a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. Functions: attachment epithelium to CT, regulation/filtration: exchange b/w E + CT, scaffolding (for regeneration).
basal lamina
Tight Junction (Zonula Occludens)
Transmembrane proteins (Occludins and Clausind) weaved back and forth through both cell’s plasma membrane several times that blocks molecular movement between intercellular space. Wrap around cell like a belt. Establishes polarity in cell.
Formation of cell/tissue masses as the result of the proliferation of neoplastic cells.
Tumor
short, finger-like projections of the apical plasma membrane & cytoplasm into the lumen. Very uniform and itghly packed. Increase SA for absorption (and secretion).
Microvilli
Paracellular Transport
Exchange of small solutes, ions, and water between lumen and connective tissue between the lateral domains. Also allows movement of White blood cells into the Connective tissue
small stud- or rivet-like structures on the inner basal surface of keratinocytes in the epidermis of skin that attach one cell to the extracellular matrix.
hemidesmosomes
zonula adherens, intermediate junction, or “belle desmosome”
Adherens junctions names
Exchange of small solutes, ions, and water to/from lumen and CT by pasing netween lateral domains. Passive provess.
Paracellular transport
