Epithelial Tissues Flashcards
What are the three embryonic layers?
The ectoderm; the mesoderm; and the endoderm
What is the Ectoderm?
The outermost of three primary germ cell layers in the very early embryo
What is the Endoderm?
The innermost of three germ cell layers in the very early embryo
What is the Mesoderm?
The middle of the three primary germ cell layers of the early embryo
What are some examples of the tissues that grow out of the Endoderm?
Most of the alimentary canal; the respiratory tract; endocrine glands; urinary bladder and part of the urethra
What is a tissue?
a group of cells with common functions
What is an organ?
two or more tissues that work together to perform a particular function
What are the four categories of tissues?
Epithelial: connective: muscular: nervous
What are 6 characteristics of epithelial tissues?
cells are close together;form continous sheets;regenerative;avascular;free or apical surface; rest on a basement membrane
What are three traits of simple squamous cells?
flat; one layer; found where diffusion and filtration occur
What are three examples of tissues comprised of simple squamous cells
alveoli; capillaries; kidneys
What are 3 traits of simple cuboidal cells?
cube like; one layer; spherical nucleus; function in secretion and absorbtion
What are 4 traits of simple columnar cells?
column shapped; nucleous near base; may be ciliated; function in secretion and absorbtion
What are 4 traits of stratified squamous cells?
top layer flat or squamous; basal layers cuboidal or columnar and growing activly; found in areas that need proection
What are some examples of tissues comprised of stratified squamous cells?
skin; vagina; mouth; pharynx; esophagus; anal canal
What are 3 traits of stratified cuboidal cells?
Rare; usually only two layers; mostly in the ducts of larger glands
Where can stratified cuboidal cells be found in the body?
sweat glands, mammary glands
What are 3 traits of Stratified Columnar cells?
rare; usually only two layers; mostly in the ducts of larger glands; only apical layer is columnar
Where can stratified columnar cells be found in the body?
portions of the pharynx; the male urethra; the junction between the two other types of epithelia; and the lining of some glandular ducts
What are Pseudostratified Columnar cells?
a single layer of cells of differing heights; some cells not reaching the surface; nuclei seen at different levels; may be ciliated and have mucous secreting cells
What are the functions of Pseudostratified columnar cells?
secretes substances; particularly mucus; propulsion of mucus by ciliary action
What are some of the locations of ciliated Pseudostratified Columnar cells?
the trachea; upper respiratory tract
What are some of the locations of non-ciliated Pseudostratified Columnar cells?
sperm carrying ducts and the ducts of other large glands
What are some characteristics of transitional epithelium?
basal cells cuboidal or columnar; surface cells dome shaped or squamouslike depending on degree of organ stretch; resembles both stratified squamous and cuboidal
Where can transitional epithelium be found in the body?
the lining of the ureters; bladder; and part of the urethra
What is the function of transitional epithelium?
to stretch readily; especially useful for the bladder which must stretch to accommodate urine
What is a gland?
one or more cells that secrete a particular product
What is a secretion?
an aqueous fluid that usually contains proteins but can also contain lipids or steroids
What is an endocrine gland?
a gland that produces hormones and secretes directly into the extracellular space
What are ductless glands?
endocrine glands
What are exocrine glands?
glands that secrete their products onto body surfaces or into body cavities
What are some examples of unicellular exocrine glands?
mucous cells and goblet cells
Where are most unicellular exocrine glands found?
in the epithelial linings of the intestinal and respiratory tracts
What is mucin?
a complex glycoprotein that dissolves in water when secreted
What is mucus?
a combination of mucin and water which serves to protect and lubricate surfaces
What are the two basic components of multicellular exocrine glands?
the epithelium derived duct and the secretory unit
What are the structural classifications of multicellular endocrine glands?
based on the duct type (simple or compound) and their secretory type (alveolar;tubular; or tubuloalveolar)
What are simple glands?
glands which have an unbranched duct
What are compound glands?
glands which have a branched duct
What are tubular glands?
glands whose secretory cells form tubes
What are alveolar glands
glands whose secretory cells form small flasklike sacs
What is a synonym for alveolar?
acinar
What are merocrine glands?
glands which secrete their products by exocytosis as they are produced
What are holocrine glands?
glands which accumulate their products within them until they rupture
