Epithelia Flashcards
(34 cards)
What is a simple epithelium?
A single layer of epithelial cells; every cell comes into contact with the basement membrane.
What is a stratified epithelium?
An epithelium composed of multiple layers of cells.
What is the structure and function of simple squamous epithelium?
Flat cells with disc-shaped nuclei; allows passage of materials by diffusion and filtration, secretes lubricating substances.
Where is simple squamous epithelium found?
Kidney glomeruli
alveoli of lungs
endothelium, mesothelium,
endocardium.
What is the structure and function of simple cuboidal epithelium?
Cube-like cells with central nuclei; functions in secretion and absorption.
Where is simple cuboidal epithelium found?
Kidney tubules
ducts
secretory portions of small glands
ovary surface
What is the structure and function of simple columnar epithelium?
Taller than wide cells with basal nuclei; can be ciliated or non-ciliated; functions in absorption and secretion of mucus, enzymes.
Where is ciliated simple columnar epithelium found?
small bronchi and uterine tubes
Where is non-ciliated simple columnar epithelium found?
- Digestive tract
- Gallbladder
- Ducts
What is the structure and function of pseudostratified epithelium?
Appears multilayered but all cells contact ECM; secretes mucus; can be ciliated or non-ciliated.
Where is non-ciliated pseudostratified epithelium found?
vas deferens and large glands
Where is ciliated pseudo stratified epithelium?
trachea and upper respiratory tract
What is stratified squamous epithelium?
Thick membrane with flattened superficial squamous cells and metabolically active cuboidal/columnar basal cells.
Where is non-keratinised stratified squamous epithelium found?
mouth
oesophagus
vagina
anus
Where is keratinised stratified squamous epithelium found?
epidermis of skin
What is stratified cuboidal epithelium?
Two layers of cuboidal cells; protects underlying tissue
Where is stratified cuboidal epithelium?
- Largest ducts of sweat
- Mammary
- Salivary glands
What is stratified columnar epithelium?
Several layers; basal cells cuboidal, superficial cells columnar; provides protection and secretion.
Where is stratified columnar epithelium found?
- Rare—urethra
- large ducts of glands
- conjunctiva of eyes
What is transitional epithelium?
Several layers; superficial cells vary shape with stretch.
Where is transitional epithelium found?
- Ureter
- Bladder
- Parts of urethra
What are tight junctions?
zonula occludens
form a “zipper” to block passage of molecules; gatekeepers of the paracellular pathway.
What are adherens junctions?
zonula adherens
Located beneath tight junctions; encircle the cell; connect to actin cytoskeleton; allow cell-cell adhesion.
What are desmosomes?
Macula adherens
Spot-like lateral adhesions; connect cells via adaptor proteins and signalling complexes.
