Epithelia Flashcards
Recall info about epithelia
-covers the internal and external surfaces
-found in various organs
-tightly packed : minimum extracellular space
-two surfaces; apical (free) and basal ( attached) surfaces
-avascular: nourishment by diffusion
-have a basement membrane
What are the functions of epithelia
-Protection and barrier function
-Absorption and secretion
-Sensory perception
-Transport
-Filtration and excretion
-Diffusion of gasses
What is the classification based on the number of cell layers
Simple
What is the classification based on the number of cell layers
Stratified
What is the classification based on the cell shape
Squamous
What is the classification based on the cell shape
Cuboidal
What is the classification based on the cell shape
Columnar
What is the function of junctional complexes ?
-assist epithelial cells to adhere to each other
-control/restrict the moment of materials between adjacent cells
Name 3 cell junctions
Tight junctions, desmosomes, gap junctions
What are tight junctions ?
-impermeable junctions
- form continuous seals around the cells -> prevents molecules from molecules passing through the intermolecular space
Which cell junction is this ?
Tight junctions
What are desmosomes?
-anchoring junctions
- bind adjacent cells together
-acts like a molecular Velcro
-helps form an internal tension reducing network of fibres
Which cell junction is this?
Desmosomes
What are gap junctions:?
-communicating junctions
-allow ions and small molecules to pass
-are particularly important for communication in heart cells and embryonic cells
What are the 6 epitheliums ?
-simple squamous
-simple cuboidal
-simple columnar
-pseudo-stratified columnar
-stratified squamous
-transitional