Epithelia Flashcards
Endothelial Tissues
Sheet-like structures that line the external (skin) and internal (cavities and lumen) surfaces of our bodies
Barriers (e.g. skin, lumen of blood vessels)
Protection
GI Tract
Absorption (intestine) and sensation (taste buds)
Genito-urinary Tract
Filtration (lining of kidney tubules)
Respiratory Tract
Exchange (alveoli)
Glandular Epithelia
Secretion (lining of glands)
Where do epithelial layers attach?
Extracellular matrix of the basal lamina
Tight Junctions
Join adjacent epithelial cells together
Prevent extracellular substances from moving down between the cells
Provide cell polarity
Anchoring Junctions
Actin Filament attachments:
1) cell-cell: adherens junction
2) cell-basal lamina: focal adhesions
Intermediate Filament attachments:
1) cell-cell: desmosomes
2) cell-basal lamina: hemidesmosomes
Gap Junctions / Channel Forming Junctions
Allows movement of ions such as Na, Ca and K
Basal Lamina
Underlies all epithelia
Formed by interactions between:
- laminin
- type IV collagen
- entactin
- perlecan
Basement Membrane
Combination of basal lamina and reticular lamina
Main function is to anchor epithelial cells to connective tissue
Simple Squamous
Function:
- absorption
- filtration
- minimal barrier to diffusion
Location:
- capillaries
- alveoli
- abdominal and pleural cavities
Simple Cuboidal
Function:
- secretion
- transportation
Location:
- glands and ducts
- kidney tubules
- covering of ovary
Simple Columnar
Function:
- absorption
- protection
- secretion
Location:
- digestive tract
