Topic 7: Tissue Level of Organization - Epithelial Tissue Flashcards
What is epithelial tissue? AKA where would you find it (2)
- covers body surface (skin)
- lines body/ organs cavities
What are organ cavities generally called?
lumen
What are the characteristics of epithelial tissue? (4)
- has one free surface (what you are protecting the organ from)
- little extracellular space between cells
- avascular (no blood vessels)
- Basement membrane
What are the characteristics of a basement membrane? (2)
- extracellular layer (not inside cell)
- attaches epithelium to underlying CT layer (formed by both tissues = “velcro”)
- blistering is an example
How is epithelial tissue classified and named? (2)
- according to the number of cell layers sitting on the basement membrane
- shape of the cells in the apical layer
What is the apical layer?
- layer touching the free surface
How would you classify epithelial tissue with:
1) one layer
2) more than one layer
of cell layers sitting on the basement membrane?
one layer = simple
more than one layer = stratified
How would you classify epithelial tissue with the shape of cells in the apical layer being:
1) flattened
2) cube/round
3) rectangular
1) flattened = squamous
2) cube/round = cuboidal
3) rectangular = columnar
What does the simple epithelia (1 layer) allow for?
- allow exchange of molecules (gasses, nutrients, etc.) for absorption/secretion
What is simple squamous epithelia? Give an example
1 layer of squished (flat) cells
ex. lungs
What is simple cuboidal epithelia? Give an example.
1 layer of cube shaped cells
ex. kidneys
What is simple columnar epithelia? Give an example
- 1 layer of column shaped (tall and thin) cells
ex. stomach, small intestine
What is stratified squamous epithelia? Give an example and how often you can find it
- apical cells squished (flat)
- common
- ex. skin
What is stratified cuboidal epithelia? Give an example and how often you can find it
- apical cells cube shaped
- rare
ex. duct of salivary gland
What is stratified columnar epithelia? Give an example and how often you can find it
- apical cells column shaped (tall and thin)
- Rare
Ex. lining of the urethra
What is pseudostratified epithelia?
- appears stratified (nuclei at different levels; not all cells reach apical surface) but all cells sit on basement membrane (= simple!)
Where in the body can you find pseudostratified epithelia?
- lines most of the respiratory tract and is ciliated
What is transitional epithelia? (3)
- cell shape (and layering) varies with stretching
- only found in inner lining of urinary system
- goes from cuboidal to squamous when stretched
ex. bladder
What is glandular epithelium?
- if the epithelia cells form a gland, the cell layer(s)/cell shape classification is no longer used, and tissue is classified as this
What is the purpose of glandular epithelium?
for secretion
What are two examples of glandular epithelium?
- exocrine glands
- endocrine glands
What are exocrine glands? (2)
- secrete products onto body surface or into a body cavity
- can be unicellular or multicellular
What are unicellular exocrine glands? (3)
- ex. goblet cells
- secrete mucus (into a cavity)
- found in the digestive, urinary, reproductive, and respiratory tract
What are multicellular exocrine glands? (2)
- consists of secretory and duct cells (ducts connect secretions to surface or cavity)
- ex. glands: sodoriferous (sweat), sebaceous (oil), mammary, difestive
