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