Epithelium DLA Flashcards
What are the types of tissue types?
- Epithelial tissues- covers body surfaces, lines body cavities, and forms glands
- Connective tissue- underlies or supports other three basic tissues structurally & functionally
- muscle tissue- consists of contractile cells and responsible for movement
- Nerve tissue-receives, transits and integrates information from outside & inside the body to control activities of the body
What are the Diverse functions of epithelium tissue?
- Secretion ex. Columnar epithelium of stomach and gastric glands
- Absorption Ex. Columnar epithelium of intestine
- Transportation Ex. Transport material on surface of epithelium with more cilia
Ex. Pseudostratified ciliated columnar epithelium of the trachea
- Mechanical protection- Ex. Stratified squamous keratinized epithelium of the skin
- Receptor function- receive & transduce eternal stimuli Ex. Olfactory epithelium of the nasal mucosa
Summarize the classifications of epithelium
- Number of cell layers
- 1 cell layer= simple
- 2+ cell layers= stratified - Cell shape of surface, nucleated layer
Squamous- width> height
Cuboidal- width= depth= height
Columnar- height > width
- Specialization of apical cell surface (when applicable)
- cilia
- microvilli
- stereocilia
- keratinized
- non keratinized
What are the functions of simple squamous epithelium ?
- exchange
- barrier
- lubrication
What are the locations of simple squamous epithelium?
- lining of heart, blood & lymphatic vessels
- endothelium
- lining body cavities
- mesothelium
- Bowman’s capsule of kidney
- Lining respiratory spaces of lung
Describe the simple squamous epithelium
- One layer of flat cells attached to basement membrane
- Cell width > height
- Apical surfaces are typically smooth
- Nuclei appear flattened
Where can endothelium be found?
Muscular artery, arteriole, venule
Where can mesothelium be found?
M3sentery
Mesovarium
What are the epithelium of the renal corpuscle?
Simple squamous epithelium
What are the types of epithelium of type 1 alveolar cells?
Simple squamous epithelium
What are the major functions of simple cuboidal epithelium?
- absorption
- secretion
- barrier
What are the typical locations of simple cuboidal epithelium?
- small ducts of exocrine glands
- surface of ovary
- kidney tubules
- thyroid follicles
- liver hepatocytes
Briefly describe simple cuboidal epithelium
- One layer of cuboidal cells attached to the basement membrane
- Cell height= width = depth
- Nuclei are typically spherical in shape & centrally located
- Apical surfaces can be smooth or have microvilli
- Some cells have long and abundant microvilli called a “brush border”
- Ex. Proximal convoluted tubules of kidney
What are ducts of exocrine glands made of?
Pancreatic duct- simple cuboidal epithelium
Surface of ovary - germinal epithelium- simple cuboidal epithelium
Kidney tubules- proximal and distal convoluted tubules
Thyroid follicles- follicular cells-simple cuboidal epithelium
Liver- hepatocytes
What are the major functions of simple columnar epithelium?
- Absorption
- Secretion
What are the typical locations of columnar cells?
- stomach
- small intestine
- large intestine
- gall bladder
- uterine tube
Describe simple columnar epithelium
One layer of columnar cells attached to the basement membrane
- Cell height > width
- Nuclei are typically oval in shape and located in the basal region
- Apical surface may have specialization depending on location & function
- microvilli
- cilia
What are the major functions of pseudostratified epithelium?
- secretion
- conduit
- absorption
What are the typical locations of the pseudostratified epithelium?
-trachea & bronchial tree
- male reproductive tract
- Ductus deferens
- epididymis
Briefly describe the pseudostratified epithelium
- One layer of cells that vary in shape and height
- most cells are columnar, but some are short basal cells (stem cells)
- pseudo= false
- Cells appear stratified (2+ layers), but ALL cells are attached to the basement membrane.
- Confirmed by electron microscopy
- Cells appear stratified (2+ layers), but ALL cells are attached to the basement membrane.
The apical surface of the columnar cells often have apical specializations
- cilia
- stereocilia
What are the major functions of stratified squamous epithelium?
- barrier
- protection
What are the typical locations of stratified squamous epithelium?
- esophagus
- vagina
- epidermis
- oral cavity
What are the characteristics of stratified squamous epithelium?
Several layers of cells with squamous cells in the superficial layer
- May be keratinized or non-keratinized depending on location & functional demand
- Only the deepest layer of cells is in contact with the basement membrane
- Main functions include protection against injury & abrasion and barrier to dehydration & infection
Describe the epidermis
Stratified squamous keratinized epithelium
- thick skin of palms of hands & soles of feet
- sc- stratum corneum= dead cells filled with keratin filaments
- SGR= stratum granulosum= most superficial layer of nucleated squamous cells
- SB= stratum basale= layer of cuboidal cells attached to basement membrane
What are the major functions of stratified cuboidal epithelium?
- barrier
- conduit
What are the typical locations of stratified cuboidal epithelium?
- sweat gland ducts
- large ducts of exocrine glands
- anorectal glands
Describe stratified cuboidal epithelium
- 2-3 layers of cells with cuboidal cells in the superficial layer
- the apical surfaces of superficial cells are often smooth
- basal cell layer attached to the basement membrane
What are the stratified columnar epithelium functions?
- barrier
- conduit
What are the typical locations of stratified columnar epithelium ?
- largest ducts of exocrine glands
- anorectal junction
What are the characteristics of stratified columnar epithelium?
- composed of two or three layers of cells with columnar cells in the superficial layer
- basal layer of cells attached to basement membrane
- not a common type of epithelium
What are the major functions of transitional epithelium ?
- barrier
- distensible property
What are the typical locations of transitional epithelium?
Urinary system
- renal calyces
- ureter
- bladder
- urethra
Describe transitional epithelium
Stratified epithelium lining urinary tract -urothelium
Surface cells often are dome-shaped- umbrella cells
In empty bladder, basal cells are mostly cuboidal, middle layer polygonal and apical cells bulge into the lumen
-In stretched bladder, thickness of the epithelium is reduced and the superficial cells are flattened
- The apical cells have extra cell membrane material near the superficial (apical) surface
- May possess two nuclei ,
What are the apical specializations of cells?
- Cilia- assist in movement of particles along apical surface
- Microvilli- increases cell surface area to facilitate absorption & secretion
- Stereocilia- increases apical surface area of cell
Where are cilia located?
- respiratory epithelium
- Fallopian tube
What are the functions of cilia?
Aiding transport of material along surface of cells
-Kartagener syndrome / primary ciliary dyskinesia
Describe cilia
Elongated, motile structures, the core of microtubules
- 5-19 um in length
- Microtubules are arranged in a consistent array of two central microtubules surrounded by nine peripheral pairs
- Cilia rise from electron dense, cylindrical structures called, basal bodies (modified centriole- MTOC)
What are the locations of microvilli ?
- small intestine
- gall bladder
- kidney
What are the functions of microvilli ?
- increasing the apical of the cell
- aid in absorption
Describe microvilli
Small finger-like projections
- 1-3 um
- brush border
Core composed of actin microfilaments (20-30)
Anchored to actin network structure called the terminal web, which contain microfilaments to stabilize the microvilli
Describe stereocilia
Elongated microvilli
-up ton120 um
Core= actin microfilaments
Function: helps in absorption
location:
- epididymis
- vas deferens
- inner ear
