Epithelial Tissue Flashcards
Types of Epithelia
surface
glandular
Surface epithelia
selective barrier b/t lumen and tissues
covers external/internal surfaces
lines tubes
Glandular epithelia
comprise functional components of many solid organs
secrete glandular products
form ducts to carry secretions
generate gametes/foster maturation
General Characteristics
highly cellular (little/no ECM)
anchor to basement membrane
polarity (apical/lateral/basal domains)
numerous junctions
avascular (lacks blood or lymph vessels)
intermediate filaments = keratin
Basement membrane
functions
structural support
physical barrier
metabolite diffusion
orient direction of growth
Basement Membrane
structure
lamina lucida = electron lucent
@ just beneath cells
lamina densa= electron dense
@ beneath lucida
lamina fibroreticularis
@ beneath densa
Lamina lucida
compostion
glycoproteins/laminins
Lamina densa
composition
collagen IV
sulfated GAGs
collagen IV primary protein of BM
forms mesh
Lamina fibroreticularis
composition
collagen III (reticulin)
collagen VII (anchoring fibrils)
small collagen I
connect/anchor densa to connective tissue
basal lamina
lucida + densa only
basal lamina
function
flexible support
molecular filter
col IV and sulfated GAG’s filter
basement membrane
components
basal lamina + lamina fibroreticularis
classification of epithelia
shape
number of layers
specializations
number of layers subgroups
simple - 1 layer
stratified- 2+
pseudostratified- 1 layer but look stratified
simple epithelia
1 layer
all cells touch BM
good for diffusion, absorption, lubrication, secretion
stratified epithelia
2+ layers
only basalmost layer touches
structural support, barriers, resist abrasion
largest ducts/conduits
stem cells located in basal layer
pseudostratified
1 layer
all cells touch but nuclei at diff levels
shape of cells
luminal/superficial layer
squamous
cuboidal
columnar
transitional
specializations
individual cells
cilia, stereocilia, microvilli
specializations
superficial layer whole
goblet cells
keratinization
types of epithelia
simple squamous
simple cuboidal
simple columnar
pseduostratified columnar
stratified squamous
stratified cuboidal
stratified columnar
transitional
simple squamous
lens shape, sunny side up eggs
diffusion, lubrication
easy tear
simple cuboidal
squarish w/large central round nucleus
small ducts, secretions, absorption
simple columnar
tall rectangles
mainly secretion and absorption so GI tract