EPITHELIUM Flashcards
Is the epithelium vascular or avascular?
avascular
epithelia rest on the ? membrane which separates it from the other tissue
basement membrane
Where can you find membranous epithelium?
covering external surfaces, lining internal closed cavities, as well as lining body tubes which communicate with the exterior
What are the 2 types of epithelium?
- Membranous
- Glandular epithelium
What are the 2 types of glandular epithelium?
- exocrine glands
- endocrine glands
How can you determine if a gland is exocrine or endocrine?
excocrine glands have a duct. endocrine glands lack a duct
What are the 3 distinct structural domains of epithelial tissue?
- apical surface
- lateral domain
- basal surface
Where is the basal surface located?
Anchored to the basement membrane
What are the main features of the lateral domain?
presence of tight junctions just below the apical surface
gap junctions above the basal surface
What is the function of tight junctions?
prevent free movement of molecules across epithelial sheets
What is the function of gap junctions?
allowing various molecules and ions to pass between cells.
allows the sharing of substances between cells.
What types of specialization can be present in the apical domain?
microvilli, cilia
define microvilli
what is the function?
hair-like projections on the surface of epithelial cells
fxn: increase SA, increase absorption of nutrients into epithelial cells
define cilia
what is an example of a function?
motile projections of some epithelial cells
fxn ex: sweep mucus and germs out of the lungs
What type of epithelia?
keratinized stratified squamous epithelium
Identify the structure idicated by A
Identify the epithelium indictaed by B
A. Keratin
B. Keratinized stratified squamous epithelium
Identify the epithelium indicated by A
List one function of this epithelium
Nonkeratinized stratified squamous epithelium
Protection
A. Identify the epithelium indicated by A
B. Identify the organelle responsible for the pale staining next to the nucleus. Why does it stain like that?
A. Simple columnar microvillus epithelium.
B. Golgi complex. Since this structure is packed with lipids, it does not bind as much eosin as the surrounding area (cytoplasm).
A. Identify the epithelium indicated by A
B. List one function of this epithelium
A.Transitional epithelium because the top layer has cells that differ in shape significantly.
B. Protection
A. Identify the epithelium indicated by A
B. Identify the tissue indicated by B
A. Transitional epithelium
B. Loose connective tissue
A. Identify the structure in A. What is the mode of secretion?
B. Identify the structure in B. What is the mode of secretion?
A. Sebaceous gland. Holocrine mode of secretion. Whole cell disintegrates and the lumen is filled with debris. Therefore, lumen is not visible. Foamy appearance.
B. Apocrine sweat gland. Apocrine mode of secretion. Apical part of cell fragments and released into the lumen. Lumen is visible and you observe fragments of cell in the lumen
A.Identify the epithelium indicated by A.
B.Identify the structure indicated by B. What does it contain?
A. Simple columnar microvillus epithelium.
B. Striated border. Contains numerous microvilli, which aid in increasing surface area for better absorption of nutrients
A. Arrows point to the nuclei of an epithelial tissue lining the lumen of blood vessel. Identify the epithelium.
B. Describe why that type of epithelium is ideal for this location.
A. Epithelium is simple squamous epithelium and the structural name is endothelium.
B. Flat, scale-like, single layer of cells fit well here (imagine how much space you have in small capillaries). Importantly, the dimension of this tissue decreases the distance gases and nutrients have to travel across the blood vessel and into surrounding tissue. Therefore, nutrients and gases (oxygen and carbon dioxide) can travel rapidly across the blood vessel.
A.Identify the epithelium indicated by A.
B.Why is this type of epithelium needed in this location?
A. Nonkeratinized stratified squamous epithelium (dog).
B. Ingested food passes through the esophagus. Depending on the nature of food ingested, it may be either nonkeratinized (dogs and cats) or keratinized (cows and herbivores that eat hard material).
