Epithelial Flashcards
What are the four types of tissues?
Epithelia
Connective
Muscle
Nervous
Three primary germ layers:
ectoderm
mesoderm
endoderm
General features of epithelia
-little extracellular material
-closely packed cells with specialized junctions
-avascular
-innervated
-apical surface exposed to body or organ cavity
-basal surface attached to basement membrane
The process where one cell type changes into a different one:
Metaplasia
What are carcinomas?
Tumors that arise from surface epithelia
What are adenocarcinomas?
Tumors that arise from glands
Functions of epithelia
-prevention of desiccation
-protection
-filtration
-secretion
-absorption
-sensory reception
Epithelium that lines cavities that connect to the outer world
muscous membrane
Layers of muscous membrane
-ectoderm (endoderm)
-basement membrane
-connective tissue (lamina propria)
-smooth muscle (muscularis mucosae)
epithelium that lines closed body cavities
serous membrane
Layers of serous membrane
-epithelial lining
-mesothelium
-basement membrane
-connective tissue
Four types of apical specialization
-microvilli
-sterocilia
-cilia
-flagella
Microvilli
surface specialization to increase cell surface area for absorption or secretion
What is the terminal web?
In the basement membrane that anchor the microvilli onto the cell
-made of cytokeratin filaments
Stereocilia
very long, non-motile microvilli
-rigid due to core of actin filament
-absorption and secretion
Cilia
-mobile, hair-like projections specialized for coordinated movement
-extension of cytoskeleton
-movement of fluids and particulate matter
axoneme
core of microtubules
(9+2 doublets)
anchored by basal body
Immotile ciliary syndrome
-genetic defect that causes uncoordinated or absent cilia
-recurrent/severe chest infection
-infertility
-hydrocephalus
Flagella
spermy
lateral surface specializations
-tight junctions
-adhering junctions
-desmosomes
-gap junctions (connexons)
Tight junction
fluid tight seals that do not allow anything in the cell or around that part of lateral portion
-present
Adherens junctions
fastens cell to one another
-beneath tight junctions
- dense plagues of myosin, tropomyosin, and vinculin
-integrins are also involved
Desmosomes
-cytokeratin filaments for shearing forces
-plaques that attach surfaces on opposing membrane
-mediated by transmembrane proteins- desmogleins
Hemidesmosome
-basal surface of cell
-anchor to basement membrane of integrins
-plaque and keratin tonofilaments
Communicating/gap junctions
allow rapid spread of information
-circular connexons in membrane
-permit passage of small molecules between adjacent cells
Basement membrane
narrow, acellular interface between epithelium and connective tissue
Major components of basement membrane
-GAGs (heparan sulfate)
-Type IV collagen
-structural glycoproteins (laminin, fibronectin, and entactin)
Three layers of basement membrane
-lamina lucida
-lamina densa
-lamina reticulus
Simple squamous epithelium
flat cells and flat nuclei
simple cuboidal epithelium
one layer of square cells with round nuclei
simple columnar epithelium
one layer of rectangle cells with oval nuclei
-can have cilia
pseudostratified columnar
there is some random cells in random places
statified squamous nonkeratinized
multiple layers of flat cells that still have nuclei on the outer most cell
stratified squamous keratinized
multiple layers of flat cells that do not have visible nuclei in the top layer of cells
stratified cuboidal epilthelium
multiple layers of square looking cells
stratified columnar epithelium
multiple layers of rectangle cells
Transitional epithelium
allow for stretching of the epithelium
-have a cap, dome, or umbrella cells
-lots of desmosomes
Simple glands
unbranched ducts
compound glands
branched ducts
Tubular glands
tube like (straight or coiled)
Acinar glands
sac-like or flask-shaped
Tubuloacinar
intermediate- tube with dilated end
Endocrine glands
release straight into the blood stream
exocrine glands
release product into ducts
goblet cells
specialized, unicellular exocrine glands
secrete mucus
merocrine
only secretory product released
apocrine
secrete membrane bound vesicles; accompanied by some cytoplasm
What is the most common type of gland?
Merocrine
What type of glands are sweat and mammary glands?
apocrine
holocrine
entire cell secreted (ruptures, releases content)
What type of glands are sebaceous glands?
holocrine
what type of gland is this?
endocrine
what types of glands are these?
exocrine
what type of gland is this?
merocrine
what type of gland is this?
apocrine
what type of gland is this?
holocrine
