Epithelial Tissue Flashcards
Tight junctions
Watertight seal between cells
-common in GI tract
Adherents junctions
Holds epithelial cells together
Gap junctions
Cell communication
muscle and nerve impulses spread from cell to cell (heart and smooth muscle of the gut)
Desmosomes
Supports cardiac muscle
Common in epidermis
Hemidesmosomes
Found on basement membranes of cells
Epithelial functions
Protection, secretion, excretion, absorption, filtration, sensation
General features of epithelial tissue
Closely packed cells
What surfaces do cells in the epithelial tissue have
Apical surface and a basal surface on the basement membrane
Why is it important epithelial tissue is avascular?
Without blood vessels- it receives nutrients and other substances from underlying tissues through diffusion
What other tissue type is avascular?
Connective tissue
Microvilli
Increase surface area, found in small intestine
Cilia
Move microbes and debris up and out of airways in the bronchus of lungs
Which layer of epidermis is most mitotically active?
Basal layer
What epithelial tissue has microvilli?
Simple columnar epithelium- specialized for absorption
What epithelial tissue has cilia?
Pseudostratified columnar epithelium - lines upper respiratory tract
What epithelial tissue has goblet cells?
Simple columnar cells- in the gastrointestinal and respiratory tracts
What is glandular epithelium?
A single cell of mass of epithelial cells adapted for secretion, derived from epithelial cells that sank below surface during development
Endocrine glands
Ductless, secrete hormones into blood stream, hormones help maintain homesostasis
Exocrine glands
cells that secrete- sweat, ear wax, salivia, digestive enzymes onto free surface of epithelial layer
What are exocrine glands connected to the surface by?
Tubes ( ducts) -
Unicellular (single celled) glands
Goblet cells
Multicellular glands
Branched ( compound) or unbranched (simple)
Simple gland types
Tubular, branched tubular, coiled tubular, branched alveolar
Compound types
Tubular, avelolar
