Epithelium Flashcards
(44 cards)
How often does cancer arise from epithelium?
75% of the tim; MAJORITY
Tissues
Group of cells closely associated in structure and function
Histology
The study of tissues
What are the four major types of tissue?
- Epithelium
- Connective
- Muscle
- Nervous
Where are epithelia located?
They COVER or LINE:
a. free surfaces (skin)
b. lining of open cavities (digestive, respiratory systems)
c. lining of closed cavities (ventral body cavity)
d. lining of blood vessels and heart (parietal pericardium (lines heart WALL) visceral pericardium (lines organ itself))}
Epithelial Gland
Skin dips down and make something in it when there is a gland
ex. gland in ear makes ear wax
What are the 4 main function of Epithelia?
- Protection- against bacterial infections, injury, etc.
- Absorption- ex. lining of digestive tract; absorbs food into blood vessels that takes food in
- Filtration- ex: renal-kidney; make urine, some goes out, some stays
- Secretion- ex. glandular epithelium
*Or any COMBO of the 4
What are the features of epithelial tissue?
- Tightly packed/little extracellular space
- exists as sheets: tight junctions and desmosomes
Apical
Top part of cell; often contain microvilli
Basal
Bottom part of cell; always attached to basement membrane
Desmosome
Anchoring junction; anchors cells together
Tight junction
Keeps in in tact so it doesn’t fall apart
Microvilli
Highly folded EXTENSIONS of the plasma membrane (it IS the membrane) that increases absorption area; brush border
Cilia
-Beat in/out; stroke to push things away
EX: filter (beat out) mucous out of mouth and catch particles while its going up. (move substances over surfaces)
-not part of the membrane; they go through the cell membrane and ANCHOR in the cytoplasm
What is the structure of cilia?
Core 9+2 microtubule doublets
Basal body (centriole)= 9 microtubule triplets
Flagella
longer projections from basal body in cilia; cell propels itself
Goblet cell
Musinagen inside them that will become mucous; not cilia covering where goblet cell is bc once it makes mucous, it pushes it out of cell
What does it mean if epithelia doesn’t sit on basement membrane?
cancer
Polarity of epithelia
cell is different all around
Basement membrane
- only epithelia have this
- two layers: basal lamina and reticular lamina
Is epithelia vascular or avascular?
Avascular; no blood vessels
Basal Lamina
- Thin layer; closest to epithelium (secreted BY epithelium)
- non-cellular adhesive layer
- selective filter of materials from blood
- template for wound repair
Reticular lamina
- Below the basal lamina
- Extracellular network of collagen fibers
Lamina means…
layer
