Histology/Epithelial Tissue Flashcards
tissue
a group of cells and their extracellular matrix specialized to perform the same function
extracellular matrix
environment around cells
4 main types of tissue
-epithelial -connective -nervous -muscle/contractile
epithelial tissue
-covers all structured surfaces -lines all hollow chambers and organs -makes up all glands
connective tissue
-provides support, structure, and transport
nervous tissue
provides a flow of information through electrical signaling
muscle/contractile tissue
provides movement
major functions of epithelial tissue
-protection -absorption -filtration -secrete/excrete -provide sensation
protection of epithelial tissue
protects from internal and external environment
Absorption of epithelial tissue
ex: nutrients from food in digestive system
filtration of epithelial tissue
-turns metabolic waste into urine -water retainment, etc.
secrete/excrete of epithelial tissue
-excretes CO2 -secretes oxygen, hormones, etc.
provide sensation (epithelial tissue)
ex: cones in retina
characteristics of epithelial tissue
-location -orientation -alignment of cells -avascular -regenerate cells
lumen
space
apical
faces empty space
basal
forms base of tissue
basement membrane
provides attatchement to other tissues
alignment of cells in epithelial tissue
-tightly packed -no extracellular matrix -allows for more permeability
permeability
-“gate keepers” -controls what gets in/out
avascular
no direct blood flow
avascular in epithelial tissue
epithelial tissue relies of adjacent tissue for blood floq
cells regenerate in epithelial tissue
-specific to epithelial tissue -very limited in all other tissues
apical adaptation
-microvilli -cilia
microvilli
-increases surface area -helps with absorption
cilia
-extension of filaments from inside cell -made of proteins that give it movement -ex: respiratory (coughing)
layers of epithelial celss
-simple -stratified -pseudostradified -transitional
simple
1 layer
stratified
2+ layers
pseudostratified
- looks like many layers but is only 1 layer
- respiration airways (trachea, bronchi, etc.) -cilia at apical surface
transitional
-2+ layers -more pliable -urinary bladder
cell shape
-squamos -cuboidal -columnar
squamos
-irregular shape -flat -good for diffusion
cuboidal
-rounded cube -central nucleus -good for. secretion
columnar
-basocentric nucleus (nucleus close to basement membrane) -slow process
simple squamos epi
-rapid diffusion/filtration -1 layer of squamos -secrete watery fluids -lines blood vessels
simple cuboidal epi
high secretion
simple columnar
-slow secretion and absorption -large intestine
stratified squamos
-2+ layers of squamos -is where mechanical stress is high (ex: jaw/mouth)
stratified cuboidal and columnar
-very rare -cuboidal: almost never find more than 2 layers -columnar: found in mammary gland
stratified transitional
-2-4 layers max -found in bladder lining -tissue can stretch to almost 1 layer
_________ makes up all glands
epithelium
types of glands
-exocrine -endocrine
exocrine
secretions are through ducts in gland to surface of tissue (ex: sweat)
endocrine
-secrete product (hormones) into extracellular matrix, then to blood -includes pituitary gland, thyroid, ovaries, testes, etc.
