3.1 Epithelial Tissues Flashcards
1
Q
What are the 4 primary tissue classes?
A
- epithelial tissue
- connective tissue
- nervous tissue
- muscular tissue
2
Q
What are the 4 cell junctions of epithelial tissues?
A
- desmosomes
- hemidesmosomes
- tight junctions
- gap junctions
3
Q
What are desmosomes?
A
they are found between cells (proteinaceous plaque and threads)
4
Q
What are hemidesmosomes?
A
they anchor cells into the basement membrane
5
Q
What are tight junctions?
A
they hold and pack cells together (like plastic wrap on a 6-pack of cans)
6
Q
What are gap junctions?
A
- they are the only communicating cell connections
- they are especially rich in smooth and cardiac muscles
7
Q
What are the 3 functions of epithelial tissues?
A
- protection (dermis)
- secretion (glands)
- absorption (microvilli)
8
Q
What are the 3 different layers of epithelial tissues?
A
- simple/pseudostratified
- stratified
- transitional
9
Q
What are the basic types/shapes of epithelial tissues?
A
- squamous (flat)
- cuboidal (nucleus is round and center of the cell)
- columnar (nucleus is elliptical and near base of the cell)
- transitional (transitions between squamous and cuboidal)
10
Q
What does epithelial tissue look like?
A
- apical surface
- lateral surfaces
- basal surface
- basement membrane (basal lamina + reticular lamina + hemidesmosomes)
- connective tissue
11
Q
How are tissues prepared?
A
- dehydrated and defatted, accomplished with changes of xylene and alcohol (“fixation”)
- embedded in paraffin blocks and sectioned into thin sections by histotechnologists
- slides commonly stianed with Hemotoxylin (purplish-blue) and Eosin (orange-pink)
12
Q
- What are the 3 characteristics of simple squamous epithelium?
A
- flattened cells, squashed, “fried eggs”
- thin layers allow diffusion and osmosis
- locations: alveoli, lining of blood vessels (endothelium)
13
Q
- What are the 2 characteristics of simple cuboidal epithelium?
A
- single layer of cube-shaped cells; nucleus is round and centered. Cells are arranged in a circle around the lumen
- locations that are ducts: glands - pancreas, thyroid, salivary glands
14
Q
- What are the 4 characteristics of simple columnar epithelium?
A
- column-shaped cells; elliptical nuclei near the base.
- goblet cells make mucus (protection)
- microvilli extant on cells of the GI tract; none on goblet cells –> increased absorptive surface area
- no blood vessels in the epithelium layer
- locations that have microvilli and needed for absorption: stomach, small intestine, gallbladder
15
Q
- What are the 4 characteristics of simple columnar CILIATED epithelium?
A
- ciliated column-shaped cells; elliptical nuclei near the base
- goblet cells make mucus (protection)
- cilia wave substances across surface (such as eggs in fallopian tubes)
- locations: fallopian tubes, ovaries (female reproductive tract)
16
Q
- What are the 4 characteristics of pseudostratified CILIATED columnar epithelium?
A
- ciliated column-shaped cells; elliptical nuclei near the base. Looks stratified but each cell makes contact with the basement membrane
- goblet cells make mucus (protection)
- cilia wave substances across surface (from deep in lungs, out). If damaged, will be replaced with squamous keratinized - why?
- locations: trachea and bronchioles
17
Q
- What are the 3 characteristics of transitional epithelium?
A
- transitions between simple & stratified arrangement, and between cuboidal/dome-shaped to squamous/flattened cells
- the ONLY epithelium that is binucleate; other binucleate epithelia would be considered malignant
- locations: lines urinary bladdar and ureters
18
Q
- What are the 4 characteristics of stratified squamous non-keratinized epithelium?
A
- layered squamous cells
- diffusion and osmosis is difficult
- upper layers will slough off
- locations that can withstand desiccation: lines mouth, vaginal canal, cervix
19
Q
- What are the characteristics of stratified cuboidal epithelium?
A
locations for a more robust lining: exocrine glands (salivary glands)
