Chapter 5 - Apical, Lateral, Basal Domains Flashcards
What does the apical domain face?
Free space
What are the 5 modifications you can have on the apical domain?
- Enzymes (ex GI tract)
- Ion Channels (signaling)
- Carrier Protiens (nutrients in, waste out)
- Structural (microvilli, steriocilia, cilia)
- Receptors (monitor environment)
What is the function of microvilli?
They increase surface area and absorptive capacity
What is the structure of microvilli?
- Interrior has 20-30 long actin flilaments in its core which connect to villin at the top and terminal web at the bottom
- the terminal web is made of mysoin II
What kind of movement does microvilli do? how?
Performs active movement via the myosin II that make up the termial web - it contacts and relaxes which move the microvilli open and close which pulls the fluid closer ot the tissue
What is microvillous atrophy (MVA)? What causes it? What are the symptoms? When does it develope?
MVA is a disease caused by a genetic mutation of the MIO 5V protien
The microvilli never make it to the apical side of the epithelial tissue, they remain stuck in the cells
Symptoms are chronic and severe diarreha, malnutrition, stunted growth, inability to gain weight
Develops hours/days after birth
What is the function of sterocilia (stereovilli)?
Facilitate absoption
What is the strucutre of sterocillia (stereovilli)?
100x longer than microvilli
core of actin filament (no villi or terminal web)
reinforced by cytoplasmic bridges made of alpha-actin at the base and throughout the length
Where are cilia located?
Present of nearly every cell in the body
What are the 3 classifications of cilia?
- Motile Cilia
- Nodal Cilia
- Primary Cilia
What is the axonemal organization of motile cilia? What kind of movement does this lead to?
9 + 2
180 windsheild wiper motion
What is the function of motile cilia?
Move particles and fluid across the epithelial surface
ex) in ovaduct and respiratory tract
What protein attaches the duplets to the central axonemal? What is it responsible for?
Dinen which is thus responsible for movement
What two protiens help attach the central microtubles in motile cilia? What is thier function?
Flexin and Radiospokes
Controls who responds
Responsible for elasticity
What is the axonemal organization of nodal cilia? What motion does this result in?
9 + 0
360 clockwise rotation
What is the function of nodal cillia?
Dispurse developemental signals in fetus/embryo development
Establish asymettry in organs
What is Situs Invertus Totalis? Which cilia is non-functional?
Reversal of internal organs
Mutation in nodal cilia - you don’t get the proper dispursment of developmental signals in embryo
What is the axonemal organization of primary cilia (monocilia)? What do primary cilia lack? What motion does this result in?
9 + 0
Lack dinen
Only passive movement
Chemical, light, and mechanical stimuli
ex) kindey fluid moves tubules which causes the release of Calcuium and begin absorption
What is Kartanger Syndrome? Symptoms? Cause?
Lack dynein which affect the nodal and motile cilia
Upper respiratory infections, sterilization if you’re man, and situs inversus totalis
Name the strucure and identify 3 prominent features which are key in the structure.
Microvillus
Villin at the tip
Actin throughout the structure
Terminal web to anchor at the bottom
What illness is being shown here?
MVA - microcillous atrophy
What is this?
Stereovillia (stereovilli)
What illness is being shown here?
Kartanger Syndrome
What structure is this?
Cilia
What structure is this?
Primary Cilia (monocilia)
Where are terminal bars located? What is thier function?
Located on the lateral membrane
Poliginal bands that encirle each other and act as cell-to-cell attachemtn sites
What are the three types of junctional complexes?
- Occuluding Junction
- Anchoring Junction
- Communicating Junction
What is the function of occluding junctions? What do they look like?
Established polarity; kepps protiens and lipids at the apical domian
Impermeable barrier; doesn’t allow exterior water through
It is a poliginal band around the apical region
What are occluding junctions made out of? (3)
Occludin - maintians barreir
Claudins - form backbone of each strand and extracellular aqueous junctions
Junctional adhesion molecules (JAM) - associated with claudins
Will increasing claudins increase or decrease permiability?
Increase permiabilit
What direction is trancellular movement?
Across the apical domain
What direction is paracellular movement?
Moving away from apical domain and towards basal domain
Is the transcellular pathway in occluding junctions active or passive transport? What about the paracellular pathway?
Transcellular is active
Paracellular is passive, it is contingent on tightness of zonula occluens
Why are occluding junctions attacked by enteric pathogens?
If you attack the occludins and claudins then you break down the junctions
If you breakdown the junctions you get increased fluid movemet from CT to the lumen which causes diareah
It disrupts the barrier protecting deeper tissues and blood vessels
What are the two types of anchoring junctions?
- Zonula Adherens
- Maculae Adherens
What is the function of anchoring junctions? (3)
- Mechanical stability by linking the cytoplams of two adjacent cells together
- Create and maintian structural integrity
- Signal transduction pathway
Where are zonula adherens located? What is the function of the zonula adherens?
Rest immediatly below zonula occulins and form a polifinal band around the cell
Interacts with acin in its cell and adjacent cells, so movements in both cells can be synchronized
What protien is the zonula adherens composed of? What does it interact with specifically?
E-cadherins “fuzzy plaque”
Homotypic interaction: e-cadherin to e-cadherin
Calcium dependent - junctions will fall apart without calcium
Where are the macula adherens (desmosomes) located? What do they interact with? What is their function?
Found throughout the lateral membrane
Interadt with intermediate fillaments
Moves the cytoplams of its cell and the adjacent cell synchronisly
Provide support - hold the cells together; often in stratified tissue
What are mecula adherens (desmosome) composed of? What structure do they form?
Desmapankins and Placoglobins form the thick plaques
Desmogeins and Desmocollins are betwen the plaques (are also calcium dependent)
Form the cadherin “zipper”
Where are communication junctions located? What is thier function?
Dispered throughout lateral domain
Permits the diffusion of small maolecules; ions, regulatory molecules, and small metabolies between cells
Helps maintain organ homeostais
What are the subunits of communication junctions? How many subunits does each cell have to make 1 junction?
Channels are formed by connexons
Each cells has 1/2 a connexon which fomr a cylindrical structue with a central pore
Each connexon has 6 subunits that can rotate together to open/close the central pore
What are Plicae? Where are they found?
Plicae are infoldings of the lateral membrane
What is the function of plicae? How do they work?
They increase the surface area which increases absoption ability
They are abundant in Na/K ATPase channels; Na leaves and inters the intracellular regions, water follows becasue diffusion, and then the fluid builds up causing swelling and moves toward the blood vessels
What structure are the arrows pointing to?
Terminal Bars
What structure is shown here?
Occluding Junctions
What structure is shown here?
Occulding Junctions
What structure is shown here?
Occluding Junctions
What structure is shown here?
Occluding Junctions
What structure is shown here?
Occluding junctions
What structure is shown here?
Anchoring Junctions
What structure is shown here?
Zonula Adherens
E-cadherin = fuzzy plaque
What structure is shown here?
Macula Adherens
Thick Plaques = desmaplankins and placoglobulins
Between plaques = desmogleins and desmocollins
What structure is shown here?
Macula Adherens
What structure is shown here?
Communication/gap junctions
What structure is shown here?
Communication / gap junction
What are the 5 main functions of the basal domian?
- Attach epithelial cell to connective tissue
- Compartmentalization
- Filtration; both ions and molecules by size
- Tissue Scaffolding
- Polarity Induction
What are the two components of the basal membrane? Which component stems from which cell?
- Basal Lamina - from epithelial tissue
- Lamina Reticularis - from CT
What staining do we use on basement membranes since HandE doesn’t work very well?
PAS staining
What are the four main groups that compose the basal lamina?
- Collogen type IV
- Proteoglycans
- Laminin
- Glycoproteins
What is the function of collogen IV in the basal lamina?
Structure
Anchors the fibrils
Creates a net like structue
What is the function of proteoglycans in the basal lamina?
Protoglycans are anionic; gives basal lamina a negative chage to filter ions
What is the function of the laminin in the basallamina?
Links to the integrins of the epithelium
What is the function of the glycoprotiens in the basal lamina? What two protiens are there?
Link the laminin and type IV collogen
Entactin - forms bridges
Nidogen - acts as reinforcement
What are focal adhesions? Where are they located? What is thier function?
Located in the basal lamina
Anchor actin filaments through integrins to the ECM glycoprotiens
Important for mechanosensitivity
What are hemidesmosomes? Where are they located? What is thier function?
Located in the basal lamina
Anchor intermediate filaments to laminins through integrins
Reinforce adhesion to CT below to prevent tears in heigh stress regions
Whare the the two types of Cell-to-ECM junctions?
- Focal Adhesions
- Hemidesmosomes
What structure is shown here?
Basal Lamina
What structure is shown here?
Basal Lamina
What structure is shown here?
Basal Lamina
What structure is shown here?
Basal Lamina
What structure is shown here?
Focal Adhesions
What structure is shown here?
Hemidesmosomes
