4: Epithelial Tissue Flashcards
What are the different polarities in epithelium?
- apical surface (free facing)
- basolateral: the sides of opposite of apical surface.
- lateral: the sides
The Germ Layers are?
- ectoderm: skin and glands of epidermis
- endoderm: GI tract lining and glands
- mesoderm: bowman’s capsule, blood vessel linings, mesothelium.
What makes up the basement membrane?
- reticular lamina: underlying connective tissue.
- basal lamina: next to epithelial.
Basal lamina
- consist of collagen IV, glycoprotein, and PAS+.
- essential for differentiation during embryogenesis
Reticular lamina
-form from glycoprotein, argyrophilic fiber (able to be stained with silver)
What is the basement membrane used for?
- barrier
- platform for embryogenesis/regeneration.
- stabilize tissue shapes.
What is Epithelial tissue?
Forms part of excretory and secretory glands, while lining cavities and surfaces of the body, and is therefore innervated.
Simple Squamous Epithelium
-major role in protection that lines tubular and are good at diffusion and filtration.
Simple Cuboidal Epithelium
- Lines ovary, kidney tubules.
- Contains a brush border (microvilli), known to form large tubule structures.
Simple Columnar Epithelium
- Column in shape.
- Excretion and secretion
- ciliated: located in uterin tube, Upper Resp. tract sinus.
- non-ciliated: gallbladder, excretory duct glands.
Stratified Squamous Epithelium
- heavy keratinization in epidermis with CT papillae. Cornea (no nucleus)
- light keratinization: esophagus, vaginal lining, tongue. (presence of nucleus)
Stratified Cuboidal Epithelia
- male urethra, anal mucosa
- rare to find
Stratified columnar epithelium
- pharynx, sweat gland duct, epiglottis.
- rare
Psuedostratified Epithelium
-appears that not every cell is in contact with BM, when it actually is.
Laminin
- major component for basal lamina.
- alpha, beta, gamma strands
- binds integrin, collagen IV, enactin, proteoglycans.
Fibronectin
- bind with heparin, integrin, collagen, fibrin
- Cellular: produces fibroblasts, ECM.
- Plasma: hepatocytes secrete into blood stream
Describe major CAMs
- cadherins (Ca dependent)
- selectins (Ca dependent)
- integrins (Ca independent)
- immunoglobulin superfamily molecules (Ca independent)
What are the epithelial tissue structure?
- no blood vessel
- display apical surface
- small intercellular matrix
What are the groups of cadherins?
- classical
- non classical
Classical cadherins are made up of?
- Epithelial cells ( have HVA binding site.)
- Nerve cells
- Placental tissue
What are groupings within selectin CAMs?
- Platelet
- Endothelial
- Leukocytes
Describe what an Integrin is. (units, binding sequence…)
- glycoprotein involved with ECM interactions
- alpha subunit: disulfide bonds of two chains.
- beta subunit: has cysteine rich areas for binding with actin.
- Binding site: RGD
Where can lightly-keratinized squamous epithelium be found?
Vaginal Epithelium
Not common stratified cuboidal epithelium may be found where?
male urethra
anal mucose
What are urothelium?
transitional eipthelium of the urinary tract
What role does catenin play in cadherins?
1) Directly link to filamentous actin. 2)interact w/ regulatory molec. of actin cytoskeleton. 3) control adhesive state
What are selectins used for and describe this process.
movement of leukocytes towards tissue. Tissue signals for help, by activating the selectin w/ Ca. Slows the leukocyte as carbohydrate ligands bind to activated selectins. The leukocyte migrates out of blood stream.
Where are immunoglobulin superfamily members from?
mRNA.
play important role of homing process, during inflammation.
What forms an Integrin?
1)binding of alpha/beta subunits. 2) transmembrane units that connect to actin via complexes. 3) RGD aa sequence on B-unit connects actin to the fibronectin/laminin.
Hemidesmosomes
Anchor basal domain to the basal lamina. Increase stability by linking intermediate filaments with basal lamina, by integrins.
What is a gap junction, and its characteristics?
used for rapid ion exchange, communication of cells. Utilize a cylinder of 6 connexin molecules. (i.e. cardiac cells for rapid electrical relay)
What is the result of a improper E-cadheren?
1) Indicates metastisis. 2) loss of cell-to-cell adhesion.
Zonula Adherens
1) found below tight junctions. 2) Use cadherens to interact with catenins.
Macula Adherens
1) provide rigidity to cell. 2) separated by wide intercellular space. 3) form cell-cell bond with cadherens.
Integrins
1) directly interact w/ laminin and fibronectin.
PAS positive structures
1)basement membrane. 2) collagens. 3)glycocalyx. 4) glycoprotein hormones.
What proteins interact with cadherins and actin?
- alpha actinin
- vinculin
- formin-1
- catenins: alpha, beta, p120
Proteins involved with integrin binding to actin?
- talin
- vinculin.
- kindlin
- alpha-actinin
- IPP complex
Microtubule inhibiting factors are?
- colchicines
- colcemid
- vincristine
- cinblastin
- all inhibit tubulin dimer formation
Taxol
-microtubule stabilizing factor
intermediatte filaments
- provide cytoplasmic network.
- type I, II, III, IV, V
Type I Int fil.
I and II are acid and basic int. filaments.
Type III int. fila.
- self assembling
- Peripherin
- Vimentin
- Glial fibrillary
- Desmin
