Epithelial Tissue Flashcards
tissue
group of cells that are similar in structure and perform a related function
histology
study of tissues
four main types of tissue
epithelial, connective, muscle, and nervous
epithelial tissue
forms boundaries between different environments, protects, secretes, absorbs, and filters
apical surface
borders open space
basal surface
next to underlying connective tissue
epithelial form
continuous sheets of cells held together by tight junctions and desmosomes
polarity
distinct apical and basal surfaces
support layer
basement membrane (basal and reticular lamina)
avascular
no blood vessels
innervated
supplied by nerve fibers
regenerative
rapidly replaces lost cell by cell division
6 aspects of epithelial tissue
form, polarity, support layer, avascular, innervated, regenerative
purpose of epithelial tissue
covers body surface or lines a cavity
1. protection
2. absorption
3. filtration
4. excretion
5. secretion
6. sensory reception
two kinds of epithelial tissue
simple- absorption, secretion, and filtration
stratified- protection
classification of epithelia
squamous
cuboidal
columnar
what does the nuclei look like in the different types of epithelia
shape of nuclei conforms to the shape of the cell
which epithelia is best for protection?
stratified
which type of epithelia is best for diffusion of gases?
simple
which type of epithelia is best for sensory reception?
simple
which type is best for packed layers of protection
squamous
which is best for secretion
cuboidal or columnar
which portion of epithelial cell in stomach would food be in contact?
apical surface
structure of simple squamous
single layer of flattened cells
disc-shaped nuclei and sparse cytoplasm
functions of simple squamous
diffusion and filtration
provides a friction-reducing lining in lymphatic and cardiovascular systems
where is simple squamous found
present in lungs, kidney glomeruli, lining of heart, blood vessels, lymphatic vessels, and serosae
endothelium
capillaries, lining of lymphatic vessels, blood vessels, and heart
mesothelium
serous membranes lining organs and cavities
structure of simple cuboidal
single layer of cube like cells
large, spherical nuclei
functions of simple cuboidal
secretion and absorption
where is simple cuboidal found?
kidney tubules, ducts, and secretory portions of small glands, ovary surface
structure of simple columnar
single layer of tall cells
oval nuclei
many contain microvilli, some have cilia
function of simple columnar
absorption and secretion of mucus
non-ciliated line entire digestive tract, gallbladder, excretory ducts
ciliated line small bronchi, uterine tubules, and part of uterus
structure of pseudostratified columnar
single layer of cells
cells have different heights
nuclei are seen at different layers
function of pseudostratified columnar
secretion, absorption, propulsion
non ciliated in sperm carrying ducts and ducts of glands
ciliated present in trachea, upper respiratory tract
structure of stratified squamous
thick membrane composed of several layers of cells
basal are more cuboidal, apical are squamous
function of stratified squamous
protection of areas subject to abrasion
keratinized cells- outer layer of skin
non-keratinized cells- moist linings of esophagus, mouth, and vagina
structure of transitional
basal cells are cuboidal/columnar
surface cells are dome shaped, can stretch to squamous
function of transitional
lines the urinary bladder, ureters, and part of urethra
stretches to permit the distension of the urinary bladder/greater flow through tubes
gland
produces and secretes fluid
endocrine
internal gland
lose their ducts during development, secrete hormones into fluid and then enter bloodstream
secrete through exocytosis
exocrine
external gland
retain connecting cells, which form a duct that transports secretions to surface
examples of endocrine glands
thyroid, pancreatic beta islet cells, ovaries, pituitary gland
how do hormones travel
through blood and lymph vessels to other organs
examples of exocrine glands
mucous, sweat, oil, saliva, bile, digestive enzymes
goblet cell
unicellular gland
secretes mucin
classifications of multicellular exocrine glands
simple, compound, tubular, alveolar
modes of secretion
exocytosis- move contents to surface, release contents to extracellular space (duct)
cell rupture- cell fills with secretion, reaches duct, whole cell falls apart, releases contents to duct
