Flashcards in Epithelium Deck (37)
What is epithelium
highly cohesive sheet of cells that lines the cavities of organs, covers or lines body surfaces and forms the functional units of secretory glands.
Basic functions of epithelium.
protection sand covering of surfaces
lubrication of surfaces
exchange of substances
What surfaces of the body do epithelium line?
All external and internal surfaces of the body. All substances that ever to leave tissues and organs must cross and epithelium.
What mechanism do epithelial cells renew?
by mitosis at a variable rate and lack blood supply.
how are nutrients delivered to epithelium?
by diffusion from tissue
How are the cell layers of epithelium maintained?
Specific cell adhesion molecules and intercellular junctions and the cells are attached or anchored to a connective tissue striation called basal lamina
What are the 8 different types of epithelium?
Characteristics of simple squamous?
single layer of flat cells with spinal-shaped nucleus
Function of simple squamous?
lining, exchange, lubrication
Location fo simple squamous?
lining of blood vessels (endothelium), lining of body cavities (mesothelium), lining of organs (serosa), lining of respiratory spaces (alveoli) in the lung.
Characteristics of simple cuboidal?
single layer of cells of equal height and width with a round centrally placed nucleus
Function of simple cuboidal?
Location fo simple cuboidal?
small ducts of exocrine glands, surface of ovary, kidney tulles, thyroid gland follicles
Characteristics of simple columnar?
single layer of cells taller than they are wide with a round or oblong nucleus located centrally or toward the basal region of the cell.
Function of simple columnar?
absorption and secretion, protection, lubrication
Location fo simple columnar?
lining of gastrointestinal system, lining of gallbladder, lining of some large ducts
Characteristics of stratified squamous?
multiple layers of cells with the outermost layer of cells squamous-shaped
Function of stratified squamous?
protection and secretion
Location of stratified squamous?
epidermis, lining of oral cavity, esophagus and vagina
Characteristics of stratified cuboidal?
multiple layers of cells with outermost layer cuboidal-shaped
Function of stratified cuboidal?
absorption and secretion
Location fo stratified cuboidal?
sweat glands and ducts, larger ducts of exocrine glands
Characteristics of stratified columnar?
multiple layer of cells with outermost layer columnar-shaped
Function of stratified columnar?
secretion, absorption, and protection
Location fo stratified columnar?
largest ducts of exocrine glands and conjunctiva of eye
Characteristics of pseudostratified?
although it appears stratified is composed of only one cell layer of vernally columnar cells. ALL cells tough the basement membrane even though they do not all reach the luminal surface. typically have cilia on apical surface.
Function of pseudostratified?
section and absorption; lubrication
Location of pseudostratified?
lining of trachea, bronchi, nasal cavity, reproductive tract (ductus deferent, oviduct)
Characteristics of transitional (urothelium)?
stratified epithelium found exclusively in part of the renal system. the shape of the top layer can change based on dissension of the underlying tissue. Accurate classification depends on knowing where it is found.