Epithelial biology Flashcards
what is epithelium?
protective layer of closely packed cells that don’t let things in and out
look at this epithelial cell structure
what do hemidesmosomes do?
connect epithelial cells to basal lamina
look at this epithelial cell structure
what do desmosomes do?
connect epithelial cells together
what are the classifications of epithelium?
one layer: simple or pseudostratified
two or more layers: stratified
what are the classifications of epithelial cells?
Flattened: squamous
Cubes: cuboidal
Columns: columnar
what type of epithelium is oral mucosa?
is stratified squamous epithelial cells
describe the Formation and maintenance of keratinised layer of epithelium
Cells proliferate and move away towards the outer area where they stop proliferating and start differentiating having lots of proteins.
what is cell proliferation?
an increase in the number of cells; a result of cell growth and cell division.
what happens in G0 of the cell cycle?
rest: cells metabolically active but no signals to divide
what happens in G1 of the cell cycle
cellular contents except chromosomes are replicated
restriction point that stops cells going into S phase due to lack of extracellular signals
cyclin-dependant kinases and cyclins interact with each other to allow the cell to go through cell division
what allows the cell to go through cell division in the G1 phase of the cell cycle?
cyclin-dependant kinases and cyclins interact with each other
what happens in the S phase of the cell cycle?
DNA and chromosomes replicated
what happens in the G2 phase of the cell cycle?
cells check that everything has been replicated correctly
what happens during the mitosis phase of the cell cycle?
two nuclei and cells split in two - cytokinesis
what controls proliferation?
Signals come via receptors in basal layer cells, via extracellular matrix through phosphorylation
what do growth factors do?
controls cell growth and differentiation. Localised
what do transcription factors do?
protein that regulates the activity of RNA polymerase
describe the cell proliferator unit
- Progenitor cells are in basal layer
Dividing cells appear in clusters
what are the two types of cell proliferator unit?
Slow dividing but always have proliferative potential
Faster dividing but limited number of divisions
There are certain cells in the basal layer that have potential to be stem cells. what are stem cells?
- Divide without limit
When divides each daughter cell has choice as to what it differentiates into
what is differentiation?
process by which cells or tissues undergo change toward a more specialised form or function
Change in gene expression
what is one of the major reasons why a cell stops dividing?
removal of alpha 6 beta 4 - laminin as this attaches the hemidesmosome to the basal lamina. So cells move away from the basal lamina and start to differentiate
what is the cytoskeleton?
system of protein filaments in the cytoplasm that gives the cell shape and movement of organelles in the cell itself
what are the most abundant components of the cytoskeleton?
actin
intermediate filaments
tubulin
