Week 2 Epithelium Flashcards
What are the 3 domains of epithileum?
Apical, lateral and basal
Classes of epithelium?
Simple, cuboidal, columnar, squamous, stratified
Pseudostratified epithelium is in what class?
Simple! Appears stratified bc the nucleii are far away from basal membrane but still connected (Ex: trachea)
endothelium
lining of blood and lymph
endocardium
lining of ventricles and atria
mesothelium
lining of surfaces and closed cavitites
urothelium
TRANSITIONAL EPITHELIUM. stratified. allows stretch. lining of bladder
3 specialized structural features of apical domain?
microvilli, stereocilia, cilia
Microvilli
actin core
transport fluid
*structure/function similar but organization different
villin and terminal web
villin
localized to the tip of microvilli
barbed end biding protein
terminal web
actin found at the base of microvilli that allows spectin and myosin to bind microvilli to plasma membrane
spectin and myosin
proteins that attach actin microvilli to the plasma membrane
stereocilia
mechano-receptors =sense movement
found in ear
NO villin protein at tip, but actin core
long, not wiidely distributed
cilia
NOT actin based
microTUBULE based internal structure called axoneme connected to MTOC (made of alpha and beta tubulin)
3 types of cilia; motile, primary, nodal
3 types of cilia
motile, primary, nodal
motile cilia
9+2 axonemal microtubule based internal structure
found in LARGE numbers ( trachea, oviducts)
Dynein motor protein
dynein
motor protein associated with motile cilia (and nodal cilia)
causes cilia to beat
USES ATP
primary cilia
9+0 axonemal microtubule based internal structure
do NOT move, no motor proteins
mechano-receptors for fluid flow (liver)
SINGLE aka MONOCILIA
coordinated with cell cycle (must remake every division)
nodal cilia
contain motor protein dynein
found in EMBRYO and important for development
Found around primitive node
3 juntional complexes
occluding= tight anchoring= adherens and desmosome communicating= gap
tight juntion/ occluding
most APICAL
a junctional COMPLEX made of occludin and claudins to form a SEAL
occludin and claudins and JAM
found in tight junction/occluding in order to form seal
desmosome/adherens
desmosome=intermediate filament, aderen=actin
anchoring junction
provide force RESISTANCE
transmembrane proteins: 1) desmogleins (Dsg) and 2) desmocollins (Dsc)
gap juntion
transmembrane channels made of connexins to allow passage of stuff between cells
connexins
transmembrane component of gap junctions that allow channels to be made
List layers of epidermis
1) stratum basale- actively dividing with KERATINOCYTES
2) spinosum- desmosomes, thick
3) granulosum- prominent granule staining
4) lucidum
5) corneum- dead
keratinocytes
cells giving rise to the epidermis
stratum granulosum is full of?
keratohyalin granules containing cysteine rich and histidine rich proteins, precurse filaggrin
Stratum corneum is full of
filaggrin that cross link keratin filaments in terminally dead cells to act as water barrier
What layer of the epidermis is limited to thick skin?
stratum lucidum
4 major epidermal cell types?
keratinocytes
melanocytes= pigment (5%)
langerhans cells= antigen presenting (2-5%)
merkel’s cells= sensory mechanoreceptors (6-10%)
two layers of dermis
1) papillary- close to epidermis, type 1&3 collagen, contain blood vessels that feed stratum basale
2) reticular- deep and thick, irrigular collagen 1
encapsulated nerve ending? (3 corpuscles)
pacinian= detect pressure and vibration meissener's= detect light touch ruffini's= detect skin stretch and torque
free nerve endings penetrate?
the granular layer
hair follicle
originates in hypodermis
responsible for making hair
hair matrix cells differentiate to give rise to?
epidermal stem cells, melanocytes and keratin producing cells of hair
hair completely made up of?
hard keratin
full of layers like skin
eccrine sweat glands
INDEPENDENT of hair
apocrine sweat glands
ASSOCIATED with hair follicle
large luminal space
SINGLE cell type= simple secretory epithelium
secretory segment of glands is where?
buried deep in the dermis or upper part of hypodermis
3 eccrine sweat gland cell types?
1) clear= secretory (stain intensely with PAS), numerous mitochondira and sER
2) dark= lots of rER and large Golgi
3) myoepithelial= can contract, responsible for expression of sweat, LIMITED to basale aspect
Stratum spinosum is full of?
desmosomes
myoepithelial cells
one type of Eccrine sweat gland cell
LIMITED to basale aspect
can contract, responsible for expression of sweat
What two apical domain structures are mechanoreceptors?
Stereocilia- sensory info, found in ear
Cilia: primary cilia- nonmotile, sense fluid movement
basal keratinocytes are attached to the basale lamina and dermis through?
hemidesmosomes (anchor intermediate filaments) and focal adhesions (anchor actin)
does the epidermis have blood vessels?
no. Must cut dermis to ‘bleed”
cadherin and catenins
Cadherin (OUTSIDE of cell) is transmembrane protein in adheren junctions that connects to Calcium outside of the cell.
Catenins link the cadherin to the actin cytoskeleton INSIDE the cell
