Epithelium Flashcards
4 basic types of tissues
Epithelial
Connective
Muscle
Nervous
Location of Epithelium
Covers surfaces
Extends into all complex invaginations
Mostly cells
Parenchyma vs. Stroma
Parenchyma: Essential/Functional
Stroma: non-essential (connective tissue, blood vessels, ducts)
Functions of epithelium
Protection (chemical and mechanical)
Control of transport (absorption and secretion)
Epithelium Characteristics
Uninterrupted layer of cells
avascular (no vessels)
Polarized
Apical
⇅
Basal
*Basal layer undergoes mitosis
Where is the basement membrane? What is it also called?
Basement membrane (aka Basal Lamina )
Between epithelium and connective tissue
Basal cell layer of epithelium
Stem cells that reside closest to the basal lamina (undifferentiated)
Mitosis (renewal/turnover)
Progenitor cells (division)
Metaplasia
Adaptation of mature tissue to physical or chemical stress
Stem cells alteration
✰Can lead to cancer (neoplasia)
Paracellular vs. Transcellular transport
Paracellular - Between two cells
Transcellular - Through a singular cell
Junctions of epithelium
*Tight: Seal
- proteins: occludens, claudins, ZO proteins
*Adherens: Anchor
- proteins: actin filaments and cadherins.
*Desmosomes: anchor (velcro) mechanical stress
- proteins: Desmogleins, desmoplakin, plakoglobin
*Gap junctions: communication
- protein: Connexin.
*hemidesmosomes: anchor to basal lamina
- proteins: integrins/laminins
*blistering disorder
Classification: epithelial types
Simple (single layer) vs. Stratifies (multi-layered)
Cuboidal, columnar, squamous (low)
keratinized vs non-keratinized
Pseudostratifies columnar
Urothelium (kidneys, ureters, bladder, urethra)
-stratified
-Stretch and leak prevention
T/F: Mast cells are resident cells of connective tissue that contain many granules rich in histamine and heparin.
TRUE
mast cells are key players in the inflammatory response.
eosinophils are associated with… and …
eosinophils are associated with INFLAMMATORY RESPONSE and ASTHMA
fibroblasts secrete most of the ___
ECM
adipocytes store energy and regulate ____
metabolism