Histology - Epithelium Flashcards - complete
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)
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
only a few, no mitosis (adult), eg, cells in core of lens, hair cells, inner ear.
Permananet Epithelium
Exchange of small solutes, ions, and water to/from lumen and CT by pasing netween lateral domains. Passive provess.
Paracellular transport
BL (basal lamina) + RL (reticular lamina) (at TEM level)
BM (at light level)
Uncontrolled proliferation of cells (failure of normal regulatory mechanisms)
Neoplasia
a benign tumor of epithelial tissue with glandular origin, glandular characteristics, or both.
adenoma
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
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
3-4 longer than MV, less ‘orderly’. Specialized to move substances along a surface.
Cilia
tight junction, barrier to paracellular transport.
Zonula Occuldens
Exchange of substances to/from lumen and CT by passing through an epithelial cell. Active process.
Transcellular transport
rows of transmembrane proteins from adjacent cells that appear as ridges or stitches that act as a barrier to paracellular transport pathway.
Junctional strands
interact with desmosomes (cell-cell adhesion) and hemidesmosomes (cell-matrix adhesion) via adapter proteins.
Intermediate filaments
Supress proliferation of epithelial cells.
Adaptor Proteins
Apical specilization that establishes extracellular microenvironments at membrane surface. Functions: metabolism, cell regocnition, receptor sites etc. Composed of: glycoproteins and glycolipids.
Glycocalyx
Special arrangement of microtubules. 9 outer doublets, and 2 central singlets. Abbreviated “9+2”. Anchored into the basal body.
Cilia core
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
Paracellular Transport
join in the intercellular space to form Junctional Strands
Occludin and Claudins
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
Adheren Junctions (Zonula adherens)
Extracellular matrix layer between epithelial cells and underlying CT. Carbohydrate base.
Basement membrane
steady state renewable, replace cells that are continuously lost. Proliferation is highly regulated (ex: epidermis, epithelium of GI tract, respiratory system, urogential systems)
Labile epithelium
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).
Microvilli
Weave back and forth through each cell’s plasma membrane several times
transmembrane proteins
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
bacteria in GI tract that attacks tight junctions and causes ulcers.
Helicobacter pylori
a carcinoma featuring microscopic glandular-related tissue cytology, tissue architecture, and/or gland-related molecular products, e.g., mucin.
Adenocarcinoma
9 triplets
Basal body MT composition
Covers, lines, secretes, absorbs
Epithelium
Integrin proteins linked to basal lamina outside cell and Actin Filaments inside cell. Aids in adhesion and mechanosensitivity.
Focal Adhesion
actin filmamentous core, cross linked to plasma membrane and other actin binding proteins. Anchored to Terminal Web (TW) (also actin).
Microvilli core skeleton
Hemidesmosomes, Focal Adhesions
Cell-to-Matrix Adherents
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
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
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.
Tight Junction (Zonula Occludens)
No CAMs, have transmembrane connexons. Aid in cell-cell communication.
Gap junctions
integrin used as adhesive moleculelinking basal lamina to cytoskeleton.
Cell-Matrix Junctions
occludin and claudins that weave through each cell’s plasma membrane and extend into ICS.
Transmembrane proteins
Formation of cell/tissue masses as the result of the proliferation of neoplastic cells.
Tumor
Directly Contacts Luminal Contents or External Area
Apical Domain
orderly series of 3 junctions, tight junction, adherens junction (ZA), desmosome (D) - terminal bar at light level.
Junctional complex (@ TEM)
influecne lots of process that occur within cell, one is suppress proliferation (contact inhibition).
adaptor molecules
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
problem with adhering type junctions, cells pull apart and space fills with fluid.
blistering
Loss of adaptor proteins causes epithelial cellad and stem cells adjacent ot wound to proliferate. New epithelial cells detach and migrate along basement membrane.
Wound repair
Increase surface area for mainly absorption and secretion between lumen/external environment
Apical Folds
zonula adherens, intermediate junction, or “belle desmosome”
Adherens junctions names
directly contacts the luminal contecnts or external environment. Site of absorption and secretion.
Apical domain
Adheren Junctions (Zonula adherens), Desmosome (Macula adheren)
Cell-to-Cell Adherents
Strong abrasionand sheering disrupts Focal Adhesions causing separation of epithelial cells from connective tissue and fluid accumulation.
Blisters
bands encircling the cell, linking adjaent cells together. Resists mechanical separation of cells.
zonula adherens
Increases surface area through interdigitation of plasma membrane of adjacent cells, aiding in Fluid and Electrolyte transportation via Transcellular pathway.
Lateral Folds
a cell junction whose cytoplasmic face is linked to the actin cytoskeleton.
Adherens junctions
a type of cancer that develops from epithelial cells.
carcinoma
Long projections used for movement of substances and cells, synchronized movement. Less organized, 9+2 arrangement of microtubules.
Cilia
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.
Hemidesmosomes
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
do not normally undergo mitosis, however retains ability if organ damaged or needs increase (ex, hepatocytes).
Stable epithelium
associated with aubdant mitochondria that increase surface area for active ion transport.
Basal folds
Desmosome Cadherin (CAM) insert into intercellular space and overlap each other, inserted into attachment plaque inside cell. Strengthened by keratin intermediate filaments.
Desmosome (Macula adheren)
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
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
Endocrine Protein-Base Hormone
