Lecture 2 - Epithelial Tissue Flashcards
where can epithelial tissue be found?
- lining of GI tract organs
- lining of hollow organs
- skin surface (epidermis)
what are the 4 general functions of epithelium?
- covering, lining and protecting surfaces
- synthesis and secretion
- sensory reception
- absorption
where does epithelial tissue receive it’s blood supply?
connective tissue
what separates the connective tissue from epithelial cells?
sheet of ECM called Basement Membrane
what are the 2 layers of the Basement Membrane?
- basal lamina
- reticular lamina
what does the high mitotic index of epithelial tissue make it more prone to?
- cancer
- mutations
- abnormal cell growth
def: malignant tumours of surface epithelium
carcinomas
def: malignant tumours of duct epithelium
adenocarcinomas
def: benign tumour of surface epithelium
papillomas
def: benign tumour in glandular epithelium
adenomas
what do cells progressing from HPV to cervical cancer look like?
nuclei grow and cytoplasm shrink
def: a pre-malignant change in the epithelium, detectable as changes in cell structure and genetics, as well as tissue structure
dysplasia
what are the 2 terms of cervical dysplasia?
- cervical intraepithelial neoplasia (CIN)
- squamous intraepithelial lesion (SIL)
which phase of cervical cancer: not much of the tissue looks abnormal and it is considered the least serious cervical pre-cancer
CIN1
which phase of cervical cancer: more of the tissue looks abnormal, most-serious pre-cancer
CIN2 or CIN3
def: stage of pre-cervical cancer where it is no longer reversible, has access to blood supply and has metastasized
HSIL -> cervical cancer
what are the 2 layers of the basal lamina?
- lamina lucida
- lamina dense
def: connective tissue deep to the mucosa
lamina propria
def: any epithelium that produces mucous
mucosa
def: one layer
simple
def: multiple layers
stratified
def: cells are very thin in cross-section: flat cells with flattened, oblong nuclei
squamous
def: cells are roughly equal in height and width; nuclei are large, spherical, and central
cuboidal
def: cells are taller than they are wide; nuclei are elongated and often acentric
columnar
where is simple squamous epithelium found?
- lungs
- capillaries
- kidney glomeruli
- body cavities
what is simple squamous epithelium specialized for?
- transport
- lesser extent: secretion
def: simple squamous epithelium lining the heart, blood vessels, and lymphatic channels
endothelium
def: simple squamous epithelium lining internal body cavities and covering organs
mesothelium
def: single layer of cuboid cells, common in glands and their ducts, line the kidney tubules and cover the ovaries, look like polygonal tiles in horizontal section. free surfaces often have microvilli
simple cuboidal epithelium
what kind of epithelium makes up the bile duct?
simple cuboidal epithelium
def: single layer of tall cells, often includes mucous producing goblet cells, often have apical specializations (microvilli), polarity can vary from central to basal
simple columnar epithelium
where can simple columnar epithelium be found?
the digestive tract, such as the inner lining of the gall bladder
def: single layer of tall cells, but variations in cell height create a multi-layered appearance (even though all cells rest on the BM), sometimes contains goblet cells
pseudo-stratified columnar epithelium
where can pseudo-stratified columnar epithelium be found?
lines the respiratory tract
what is special about the apical surface of the respiratory epithelium?
it acts as a mucocillary escalator to entrap and rid airways of foreign invaders by sweeping, coordinated ciliary motion
def: cells at the apical surface are flattened; underlying cells can be cuboidal or columnar, provides protection where friction is common, can withstand abrasion
stratified squamous epithelium
where is stratified squamous epithelium found?
- skin
- oral cavity
- esophagus
in areas exposed to air and abrasion, what covers the epidermal surface for more protection?
- dead cells lacking nuclei
- plates of keratin
keratin prevents ______________ and provides ________________
desiccation and provides protection
______ cells are mitotically active and continuously divide into daughter cells that mature and are pushed toward the surface to die and slough off
basal
how often is keratinized epithelium renewed?
every 15-30 days
how often is non-keratinized epithelium of the oral cavity turnover?
much more rapid than keratinized
def: relatively rare in adults, lines ducts of sweat glands, usually with 2 layers of cells
stratified cuboidal epithelium
def: extremely rare in adults, found in pharynx and larynx, conjuctiva of eyelids, and part of male urethra
stratified columnar epithelium
def: typically consists of basal cuboidal cells, intermediate, and apical columnar cells
stratified columnar epithelium
def: modified stratified epithelium that lines the urinary bladder, shape of cells and number of layers depends on state of bladder, rapidly adapts to distension and contraction
transitional epithelium
where is transitional epithelium found?
urinary bladder
def: invaginates from the surface in development to become specialized for production and secretion
glandular epithelium
def: collections of epithelial cells that are highly specialized for secretion of a particular product
glands
def: connected through ducts to the surface epithelium from which they originated
exocrine glands
def: not directly connected to the epithelial surface from which they developed; exist as separate entities and release their secretions directly into the blood
endocrine glands
def: produce clear, watery solution, usually containing enzymes
serous gland
def: produce mucous or glycoprotein mixture
mucous cells
def: contain both serous and mucous cells
mixed glands
what is an example of a mixed gland?
salivary glands
what is an example of a mucous cell?
Brunner’s glands in the duodenum
serous cells are _________ or ___________ rather than cuboidal
columnar or pyramidal
