55 terms

Intro to Epithelium

epithelium lines all body surfaces except _______
articular cartilage
what are the four major tissue types?
1) epithelium
2) connective
3) muscle
4) nervous
ectodermally derived structures
epithelium of mouth, nose, paranasal sinuses, part of pharynx, epidermis, hair, nail, ALL glands, lens of eye, cornea, enamel, anal canal
endodermally derived structures
entire digestive tract, respiratory tract, urinary bladder, prostate, vagina, thyroid and parathyroid
mesodermally derived structures
kidneys, ureters, adrenal cortex, gonads and genital ducts, blood vessels and lymphatic vessles, mesothelium
epithelial function in the skin
barrier protection
thermoregulation (sweat)
synth of Vit D
epithelial function of intestines and kidneys
nutrient absorption
epithelial function of glands
epithelial function of teeth
produce enamel matrix
3 types of epithelium
simple epithelium means ____ layer
complex epithelium is also called _____ and consists of _____ layer
stratified, 2+
the basement membrane connects ______ to ______
all epithelium to CT
the basement membrane is ACELLULAR but contains
proteins and polysaccharides
cytokeratins are produced by ______
all epithelial cells
cytokeratins are _____ ______ proteins
intermediate filament proteins
two classes of cytokeratins
type I (acidic), K9-K20
type II (basic or neutral) K1-K8
cytokeratins are found how?
in pairs
simple squamous epithelium is found in ______ and ______
endothelium and mesothelium
simple squamous morphology
flattened cells with central nucleus
the functions of simple squamous depend on their location:
- oxygen exchange (blood vessels)
- CO2 exchange (blood)
- protective barrier
simple cuboidal epithelium is found in 3 places
- glandular ducts
- kidney tubules
- thyroid follicles
simple cuboidal morphological
cube-shaped with central nucleus
functions of simple cuboidal epi
- absorption
- secretion
- active transport
simple columnar are found in ______ and ______
intestinal lining cells and ameloblasts
simple columnar morphology
rectangular-ish with nucleus positioned to one side
simple columnar functions
- absorption
- secretion
pseudostratified columnar location
lines respiratory tract
pseudostratified columnar morphology
- multi-layered
- columnar shaped
- variable nuclear position that make it look multilayered
- ciliated
pseudostratified columnar cells may be intermixed with ____________________
mucous-secreting goblet cells
transitional epithelium is what type of epi
stratified epithelium
transitional epi is able to
contract and expand
the surface cells of transitional epi are
round when contracted and flat when expanded
transitional epi is found in
urothelial structures - urinary bladder
the apical surface of the epithelium
- "free" surface
- cell surface specializations
- lines lumen
the lateral surface of epi
- does cell-cell adhesion and communication
the basal surface of epi
- does cell-ECM adhesion to basement membrane
3 types of apical specializations
1) microvilli
2) sterocilia
3) cillia
microvilli apical specialization morphology, function, composition
- non motile cellular extensions
- increase SA
- composed of actin
- breakdown nutrients using enzymes
microvilli can be destroyed by these diseases
malabsorption and diarrhea
stereocilia apical specialization morphology, function, and location
- similar to microvilli but longer
- composed of actin
- increases SA for absorption
- found in ductus deferens, epididymis, and hair cells of inner ear
cilia can be motile or non-motile - where are these found?
motile - respiratory tract, trachea, fallopian tubes
nonmotile - all other cells with cilium, eye, nose
function of cilia
- chemosensation
- thermosensation
- mechanosensation
genetic ciliophaties
- male infertilities
- ectopic pregnancies
- polycystic kidney disease
do we need to know legnths?
morphology of cilia
- 9+2 orientation
- made of microtubules
- all originate from basal body which is 9x3
3 types of epithelial cell junctions
- occluding junctions (tight)
- anchoring junctions
- communicating junctions (gap)
occluding (tight) junctions
- lateral wall near apical surface
- where cell membranes join together
- determines epithelial polarity
- impermeable to water and solutes, proteins
- forces cells to pump nutrients
tight vs. leaky epithelium tight junctions
- tight - intestine
- leaky - blood vessel to transport matter
transmembrane proteins that do tight junctions
- occludins
- claudins
gap junctions
- not just epi cells
- directly connects cytoplasms of cells
- allow passage of small molecules
structure of gap junctions
- six connections form a cylinder with central pore
- 21 distinct genes
- the connections align to form a hydrophillic channel
gap junctions participate in
- proliferation and differentiation
genetic diseases associated with connexion mutations
connexion 26 defects cause deafness, KID syndrome
KID syndrome
- defect in gap junctoins
- scaly skin
- deafness