Ch 4 Epithelium Flashcards
An avascular tissue lining exterior body surfaces and internal cavities. ex: skin
Simple Squamous
- -Vascular system-Exchange, barrier sys in CNS
- Bowman’s capsule-Exchange,lubrication,-
- Lung spaces-Barrier
- Body cavities-Exchange
Simple Cuboidal
- Small ducts of exocrine gland-Absorption, conduit
- Surface of ovary: Barrier
- Kidney tubules: Absorption,secretory
Simple columnar
- Small intestine and colon: absorption, secretion
- Stomach lining and gastric glands; secretion
- Gallbladder: absorption
Pseduostratified
- Trachea/bronchial tree:secretion,conduit
- ductus deferens: same
- efferent ductules of epididymis: absorption, conduit
stratified squamous
- epidermis: barrier, protection
- oral cavity/esophagus-same
- vagina-same
stratified cuboidal
- sweat gland ducts; barrier conduit
- large ducts of excocrine glands: same
- anorectal junction: same
stratified columnar
- largest ducts of exocrine glands: barrier, conduit
- anorectal junction
transitional (urothelium)
Renal calyces
Ureters
Bladder
Urethra-Barrier,distensible property
What are 3 types of junction?
- Tight junctions (Zone occludens, facia occludens)
- Adhering, Anchoring junction: Zonula Adherens, Hemidesmosomes, desmosomes
- Gap junction
Give Epithelium functions
- secretion
- absorption
- transport
- protection
- receptor function
Types of multicellular glands
- Simple tubular:large intestine,
- Simple coiled tubular: Skin, sweat glands
- Simple branched tubular: Stomach, pylorus, mucous secreting
- Simple acinar: urethra
- Compound tubular: duodenum
- Compound acinar: pancreas, excretory portion
- Compound tubuloacinar: Submandibular salivary gland
Give 3 basic release mechanisms
- Merocrine-to apical, vesicle fusion (pancreatic cells). excocytocis
- Apocrine: w/ cytoplasm/plasma memb surrounding vesicle (Lactating mammary gland). “Pinching off” of cytoplasm
- Holocrine: programmed cell death releases product (sebaceous glands in skin). bulk release of whole cells.
What does epithelium derive from?
- ectoderm- skin
- endoderm - digestive tract
- mesoderm - serous linings of body cavities
- mesothelium
- lining of circulatory system
Ex of simple squamous
pulmonary alveoli, parietal layer of Bowman’s capsule, thin segments of Henle’s loop in kidney, rete testis, inner ear, endothelium of blood and lymph vessels
ex of simple cuboidal
-follicles of thyroid, surface of ovary, choroids plexus, capsule of lens, pigment epithelium of retina, ducts of glands
ex of simple columnar:
-ciliated
- epithelium of digestive tract, large excretory ducts of some glands
- uterus, oviducts, pulmonary bronchi, paranasal sinuses, central canal of spinal cord
ex of stratified squamous:
-keratinized
- skin, lining of oral cavity, epiglottis, esophagus, conjunctive and cornea, vagina, distal portion of urethra
- dry scales, exposed surfaces, lose nucleas,
ex stratified columnar epithelium:
-ciliated
- fornix of conjunctiva, cavernous urethra, pharynx, small areas of anal mucous membranes, large excretory ducts of salivary glands
- nasal surface of soft palate, larynx, fetal esophagusu
ex of pseudostratified:
-ciliated
- male urethra, excretory duct of parotid gland
- trachea, primary bronchii, auditory tubes, part of tympanic membrane, lacrimal sac
ex of transitional (uroepithelium)
-urinary bladder:
empty-many layers, distended-2 layers
-urinary tract-renal calyxes of urethra
Tight of occluding junctions:
- zonula occludens
- fascia occludens
-partitioning function of connecting ridges that occlude intercellular space; selective seal
- continuous belt-like, made up of integral membrane proteins, selective diffusion barrier
- actin filaments
- occludens
- actin filaments
-interrupted tight junctions, strip or band-shaped ex endothelial cells of blood vessels
-
Adhering or Anchoring junctions:
- Zonula adherens or adhesion belt
- Macula adherens or Desmosomes
- Gap Junctions
- -below zonula occludens
- “terminal bars together with occludens
- slight e- dense material contain adhesion domains of cell membrane glycoproteins
- major site of anchorage of microfilaments
- lateral adhesion
- cadherin-catehin complex + vinculin & alpha-actinin -> actin filaments
- calcium-dependent
- -circular and spot-like
- separate plaques arranged in row
- convergence of intermediate filaments by attachment plaques
- transmembrane linker glycoproteins bind adj identical molecules of neighboring cell-strong cell-to-cell adhesion (cahedrin zipper)
- wider intercellular space
- Hemidesmosomes: half of desmo, anchor keratin-containing filaments to underlying basement membrane
- permits passage of ions and small molecules to diffuse freely between cells
- reduce resistance to passage of electric current
- 2 Connexons in each channel- hexonally packed annular units, cylindrical, dumbbell-shaped, made of 6 connexins
Lateral Interdigitating
increase surface area, engaged in fluid and electrolyte transport
Basement membrane
- define
- consists of
- zones
- function
-structures for attachment to connective tiss
- thin supporting layer bet epithelium and underlying connective tissue
- type IV collagen, laminin, proteoglycans, entactin & fibronectin
- lamina lucida and densa
- lamina propria-the connective tiss layer of mucous membrane.
- support epithelium, passive molecular sieve or ultrafilter, repair tissue, compartmentalization
- reticular fibers underlies basal lamina
- Anchoring fibrils, fibrilin microfibrils, discrete projects of the lamina dense
Classifying Exocrine glands
- Duct arrangement:
- Simple-unbranched
- Compound-branched - Shape of Secretory units:
- tubular
- alveolar or acinar
- tubuloalveolar
- saccular - Type of secretion
- Serous
- Mucous
- Mixed: (bulk-mucous glands, serous demilunes) - Secretory Mechanism
- merocrine
- holocrine
- apopcrine
Simple Exocrine Glands
- Simple tubular: straight tubules, (-) duc,
- Simple coiled tubular: Coiled:
- Simple branched tubular: bifurcate w/ short
- Simple acinar: bulbous or bottle-shaped
Compound Exocrine Glands
- Compound tubular: Tubules more or less coiled
- Compound acinar: bulbous, pear-shaped terminals
- Compound tubuloacinar: short tubules, have a number of acini along their sides and blind end
Example of Unicellular glands
Goblet cells, surface lining, glands of intestines, and respiratory tract
Derivatives of Ectoderm
- Surface
- epidermis, hair, nails, cutaneous, mammary glands
- ant pit glands
- enamel of teeth
- internal ear
- corneal epithelium, lens of eye - Neuroectoderm
- neural crest: cranial/sensory gang & nerves, adrenal medulla, melanocytes, pharyngeal arch cartilages, head mesenchyme, Schwann cells
- neural tube: CNS, retina, pineal body, post pit gland
Mesoderm derivatives
- muscles of trunk and skeleton except skull
- dermis of skin
- connective tissue
- skull, dentin
Epithelium
- urogenital system including gonads, ducts, and accessory glands
- connective tissue and muscle of viscera and limbs
Mesothelium
-serous membranes of pleura, pericardium, peritoneum
Endothelium
- blood and lymph cells
- cardiovascular and lymphatic systems
- spleen
Derivatives of Endoderm
Respiratory
- trachea
- bronchi
- lungs
Alimentary canal
-GI tract
Extramural digestive gland
- liver
- pancreas
- urachus
- pharynx
-thyroid gland
Auditory tubes
- tympanic cavity
- pharyngotympanic tube
- tonsils
- parathyroid glands
Microvili Free surface
(striated border-more highly ordered/uniform-intestines
or brush border-kidney)
-slender, finger-like, cylindrical membrane bound cell processes.
-core of actin filaments in association w/ myosin I, that binds them to plasma memb of microvillus.
-anchored to vilin tip
-supported by Terminal Web underneath, made of spectrin, myosin II, tropomyosin for contractile ability.
-cross-linking bundle of 25-35 actin filaments of
proteins fascin and fimbrin
- 1-2 um long, 80-90 nm diameter
- glycocalyx-delicate branching filaments along luminal surface; terminal oligosaccharides of integral membrane proteins
- increase digestive and absorptive effieciency of epithelium
Stereocilia Free Surface
- tuft of long, slender processes
- nonmotile
- core bundles of actin microfilament, cross-linked by fimbrin.
- anchors to plasma membrane of stereocilia by erzin
- stem cross-bridging of alpha-actinin
- Function: -limited to epididymis, absorption
- ear hair cells, sensory
Kinocilia/Cillia Free surface
-specialized for transport of fluid or mucus along epithelial surfaces
-axoneme-core complex of longitudinal microtubules
-center: 2 single microtubules
-periphery: 9 doublet microtubules
(in one doublet, cilary dynein is attached on A-microtubule then connects to B-microtubule of adjacent doublet, then bound by nexin-uses ATP)
-base: basal body of nine short microtubule triplets
-7-10 um length, 0.2 cm diameter
Flagella Free Surface
- similar to cilia
- 15-200 um
