Epithelial Tissue Flashcards
What junctions are in Terminal bars?
Tight junction, zonula adherens, desmosomes
What junctions are in intercalated disks?
Zonula adherens (modified), desmosomes, gap junctions
What are the 2 functions of basal cell membrane infoldings?
Increase surface area and intense transport of molecules across the basal cell membrane
How are mitochondria oriented in basal cell membrane infoldings?
Vertically
What is the only form of extracellular substance in the epithelial tissue?
Basal lamina
What are the proteins in basal lamina?
Laminin, collagen IV, entactin
What is the proteoglycan that can be found in basal lamina?
Perlecan
What is the basement membrane composed of?
Basal lamina and reticular layer produced by CT
What makes a gland exocrine?
Secretion through ducts
What makes a gland endocrine?
Secretion directly to the bloodstream
What makes a gland simple?
A single, unbranched duct
What makes a gland compound?
Multiple branched ducts
What is an eccrine mode of secretion?
Secretion by exocytosis
What is an apocrine mode of secretion?
Secretion of lipid droplets by pinching off of a part of a cell from the apical surface
What is a holocrine mode of secretion?
Cells accumulate the secretory material, die and break down and liberate the material
What forms of epithelial tissues are there?
Linings and glands
Is epithelial tissue vascular or avascular?
Avascular
What are the functions of epithelium?
Protection, absorption, secretion, transport control, sensation
What is the main function of simple squamous epithelium?
Transport control
Where is simple squamous epithelium found?
Vessels, peritoneum and pleura, pulmonary alveoli, Bowman’s capsule
What are the main functions of simple cuboidal epithelium?
Resorption and secretion
Where is simple cuboidal epithelium found?
Renal tubes, glands and ducts, lens epithelium, ovary-covering epithelium
What are the main functions of simple columnar epithelium?
Resorption, secretion, protection, transport control
Where is simple columnar epithelium found?
Alimentary tract, bile ducts, female genital tract, larger excretory ducts of glands
What are the main functions of pseudostratified epithelium?
Protection, secretion, sensation
Where is pseudostratified epithelium found?
Respiratory tract, epididymal duct, taste buds
What is the main function of stratified squamous epithelium?
Protection
Where is KERATINIZED stratified squamous epithelium found?
Epidermis
Where is NONKERATINIZED stratified squamous epithelium found?
Oral cavity, throat, esophagus, anus, vagina, cornea
What is the main function of transitional (stratified) epithelium?
Protection
Where is transitional (stratified) epithelium found?
Urinary tract
How do cells regenerate in simple epithelia?
Through apoptosis and replacement by newly differentiated cells
How do cells regenerate in stratified epithelia?
Cells continuously migrate from basal to superficial layer, and old cells detach from the superficial layer
What filaments are in microvilli?
Actin filaments
What is the function of microvilli?
Increase in apical membrane surface area
How is active bending of cilia generated?
By movement of dynein arms
What is responsible for passive backstroke of cilium?
Elastic nexin
What are the main function of cilia?
Movement and transport
What do nonmotile cilia act as?
Mechanosensors
What filaments are in stereocilia?
Actin filaments
What transmembrane proteins are present in tight junctions?
Claudins, occludins, nectin, JAMs
What are the functions of zonula occludens?
Prevention of uncontrolled passage of substances and maintaining polarisation of epithelial cells
What do adhesion belts connect?
Cell membranes and cytoskeletons of adjacent cells
What linker proteins are in zonula adherens?
Cadherins
What filaments are in adhesion belts?
Actin filaments
What linker proteins are in desmosomes?
Desmogleins
What filaments are in desmosomes?
Intermediate filaments
What junctions are NOT cell-cell but cell-extracellular matrix?
Focal contacts and hemidesmosomes
What linker proteins are in focal contacts?
Integrins
What filaments are in focal contacts?
Actin filaments
What linker proteins are in hemidesmosomes?
Integrins
What filaments are in hemidesmosomes?
Intermediate filaments
What linker protein complexes are in gap junctions?
Connexons
What filaments are in gap junctions?
None. No cytoskeleton involvement. Hehe
What is the function of gap junctions?
Propagation of stimuli between adjacent cells and direct exchange of metabolites and signalling molecules (passage of small molecules from the cytoplasm of one cell to the adjacent one)
What type of junctions is calcium ion concentration crucial for?
Gap junctions
