Epithelium Flashcards
General fxns of epithelium
Absorption
Secretion
Provide a barrier
What are the two parts of the basement membrane
basal lamina- produced by epithelial cells
reticular lamina- produced by fibroblasts in CT
Which part does a partial basement membrane have?
basal lamina
Functions of a basement membrane
- provide a surface for epithelial cell attachment
- molecular filter
- limit stretch (prevents damage)
T/F epithelium is avascular
true
how do epithelial cells obtain nutrition?
diffusion
what is the functions of CT that epithelial cells are connected to
provide nutrition.
source of defensive cells
Types of cell junctions (4)
Zonula Occludens (aka tight junctions) Zonula Adherens (aka adhesion belt) Macula Adherens ( desmosomes) Gap Junctions
Zonula Occludens (aka tight junctions)
these junctions involve the sharing of intrinsic membrane proteins between adjacent cells. Like a girdle around the cell
Fxns of Zonula Occludens
provide a strong attachment.
prevent the passage of materials between cells
Zonula Adherens (aka adhesion belt)
these are regions consisting of cadherins (linking proteins) between cells and marginal bands (microfilaments) which attach the cytoskeleton to the cell membrane at these areas.
Fxns of Zonula Adherens
Strong attachment.
provide cell structural stability
Macula Adherens ( desmosomes) functions
provide strong attachment
Gap junctions
6 connexins arranged in a cylinder. The size of the openings can be controlled by the cell. A connexon = ! complete structure.
Osteocytes use gap junctions
Fxns of gap junctions
strong attachment.
transport materials. ex) communication
Junctional Complex
3 junctions in the following order beginning with the free cell surface:
Zonula Occludens
Zonula Adherens
Macula Adherens
what is NOT considered part of a Junctional Complex
gap junctions
Simple Squamous
A single layer of flattened cells
example locations of Simple Squamous
lung, parietal layer of the bowmans capsulein the kidney, serosa on the outside of organs
Fxns of Simple Squamous
provides a barrier and a living filter
Simple Cuboidal
a single layer of cube shaped cells; nucleus occupies much of the cell cytoplasm
example locations of Simple Cuboidal
exocrine ducts, thyroid follicular cells, kidney tubules
fxns of Simple Cuboidal
provide a barrier.
secretion.
absorption… in some locations
Simple Columnar
single cell layer that have height; more cytoplasm; rectangular in shape
example locations of Simple Columnar
stomach, small intestines, gallbladder, ;arger exocrine ducts
fxns of Simple Columnar
provide a barrier.
secretion.
absorption
Types of ciliated pseudostratified columnar epithelium
goblet cells.
ciliated columnar cells.
basal cells
example locations of ciliated pseudostratified columnar epithelium
trachea, respiratory region of nasal cavity, bronchi
Goblet Cells
modified columnar cells that produce mucus
ciliated columnar cells
columnar cells that contain cilia. which are anchored to the base of the basal bodies. the function to move mucus over the surface
basal cells
short pyramidal cells that does not reach the surface. they function to be the stem cell for ciliated pseudostratified columnar epithelium
example locations of microvilli
kidney tubule cells, small intestines
example locations of stereocilia
cochlear hair cells
example locations of cilia
trachea, fallopian tube
glycocalyx
a surface layer of glycoproteins and carbohydrates that cover some epithelium. produced by epithelial cells.
fxns of glycocalyx
protection and call recognition
example locations of glycocalyx
stomach and small intestines
stratified squamous
multiple layer of calls that tend to flatten out from basal layer to superficial layer; superficial layer of cells are flat and alive.
example locations of stratified squamous
esophagus, oral cavity, tongue, vagina
function of stratified squamous
Protection from abrasion
Problems with stratified squamous
no protection fro drying, and they have a limited thickness so protection is limited.
Keratinized Stratified Squamous (aka epidermis)
multiple layer of calls that tend to flatten out from basal layer to superficial layer; superficial cell layer is covered by an added nonliving layer of keratin
Fxn of Keratinized Stratified Squamous
protection in a dry environment
stratified cuboidal example locations
larger ducts in sweat glands and salivary glands
function of stratified cuboidal cells
to increase protection
stratified columnar example locations
large ducts in pancreas, parts of the male urethra, conjunctiva of the eye
functions of stratified columnar cells
to increase protection and provide transition between epithelial types
how common is stratified columnar cells
Very Rare
Transitional (urinary)
= urothelium
multiple layer of cells
functions of Transitional cells
protection and to stretch
Specializations of Transitional cells
Thin fenestrated basement membrane.
LArge rounded superficial cells.
Well developed Zona Occludens
Psoriasis Vulgaris
patchy skin lesion. accelerated keratinocyte life cycle- 1 week cells accumulate in stratum corneum inflammation in dermal papillae cyclic and etiology is unknown
Freckles
spots with extra pigment.
increase in melanin without an increase in melanocytes.
tend to fade in winter and darken with sun exposure.
vitiligo
patches which lack melanocytes.
unknown cause but often associated with systemic disease
moles
aka naevi
discoloration due to a proliferation of melanocytes
malignant melanoma
melanocytes become mitotically active and invade dermis.
very invasive and metastatic.
treatment; surgery and chemotherapy
Albinism
Cause: melanocytes fail to produce melanin.
Most common form: tyrosinase is missing from melanocytes. it is a catalyst in the conversion of tyrosine to melanin
Acinus
smallest division of a gland; a group of cells surrounding a cavity
serous demilune
a small group of serous cells attached to a musus acinus
Myoepithelial cells
contractile cells with epithelium origin. these cells wrap around the acinus and sometimes the ducts in some exocrine glands
example locations of Myoepithelial cells
salivary and sweat glands; lacrimal glands; lactacting mammary glands
functions of Myoepithelial cells
assist secretion
serous glands
produce proteins
found in the pancreas, parotid gland, chief cells in stomach.
characteristics of Myoepithelial cells
trapezoid shaped, nucleus is typically round and noticeable, cells pick up stain
Mucus glands
produce mucus.
found in goblet cells, mucus cells in the stomach, minor salivary glands in tongue and palate
characteristics of mucus glands
typically stain light. nucleus is often flat and peripheral
mixed glands
produce serous and mucus.
found in sublingual glands and submandibular salivary glands
characteristics of mixed glands
serous demilunes are possible
