Lecture 01 and 02, Epithelia and CAMs/Junctional Complexes Flashcards
What are the two layers of the basement membrane
Basal Lamina and Reticular Lamina
What produces the Basal Lamina?
Epithelium
What produces the Reticular Lamina?
Connective Tissue
What are the 4 components of the Basal Lamina?
- Laminin 2. Type 4 Collagen 3. Entactin (nidogen) 4. Proteoglycans
What are the characteristics of Laminin
major component of the basal lamina made of 3 chains: Alpha, beta and gamma binding sites for integrins, type 4 collagen, enactin and proteoglycans (heparan sulfate)
What are the characteristics of Type 4 collagen
Does not form fibrils like type 1 Produced by epithelial cells, unlike type 1 collagen that is made by fibroblasts.
What are the characteristics of fibronectin?
binding sites along the laminin made of two polypeptide chains that are cross linked by DISULFIDE bonds
What are the forms of fibronectin?
Cellular- made by the fibroblasts, part of the extracellular matrix and Plasma- secreted into the blood stream by hepatocytes.
What are the binding sites on Fibronectin?
- Heparin (proteoglycan) 2. Integrins 3. Collagen 4. Fibrin
Which are the molecular complexes that primarily serve to prevent paracellular transport?
zonula occludens
Simple, non‐ciliated columnar epithelium is most like to be found associated with what?
Digestive tract. Note: different modifications to the apical domain happens along the GI tract, depending on the function.
Junctional complexes are associated with which cellular domains?
basolateral domain
Transitional epithelium is associated with which of the following?
Urinary bladder and parts of the ureters
The extracellular domains of which of the following bind to molecules in the extra cellular matrix such as fibronectin and laminin?
A. Cadherins
B. Integrins
C. Selectins
D. Immunoglobulin Superfamily
B.
Integrins
Stratified cuboidal epithelium may be found where?
parts of the male urethra
Also the anal mucosa and large excretory ducts of some glands
Lightly keratinized stratified squamous epithelium is characteristic of which location?
vaginal epithelium
lining of mouth
esophagus
tongue
and part of the epiglottis
Which of the following serve as a major interface between the cadherins that hold adjacent cells together and their actin cytoskeletons?
A. Proteoglycans
B. Catenins
C. Laminins
D. Keratins
C. Catenins
Which of the following are molecular complexes that anchor cells together and reinforce the physical integrity of tissues and the cells that make up the tissues?
zonula adherens
Which of the following types of cell adhesion molecules is associated with zonula occludens and desmosomes?
cadherins
Which of the following are only associated with the basal domains?
A. zonula adherens
B. zonla occludens
C. Hemidesmosomes
D. Desmosomes
hemidesmosomes,
note: Integrins can be found on both the basal and the lateral domains
The basal lamina is associated with which type of collagen?
type IV
Desmocollins and desmogleins belong to which of the following groups of CAMs?
Cadherins
Which of the following are molecular complexes that primarily serve to prevent paracellular transport?
zona Occludens
Where can ciliated epithelia be found? Why is this particlar cell type found in those places?
Trachea, cilia promote the removal of irritants from the upper respiratory tract. Additionally, the ciliary elevator works to help the body dispose of trapped particles within the lungs.
Oviduct: cilia helps to “wave” the ovum down the oviducts to the uterus
Which two types of cell adhesion molecules are considered CALCIUM DEPENDENT?
- Cadherins
- Selectins
What two types of CAMs are Calcim INDEPENDENT?
the immunoglobin superfamily and integrins
Why doesn’t epithelium get it’s nutrients from the blood stream? How does it receive nutrition?
The epithelium is avascular. Nutrients are passed by diffusion.
Describe a highly keratinized cell, what unique feature can we look for to help us classify?
The nucleii of a highly keratinized cell is absent.
What type of epithelium would we expect to find lining blood vessel walls?
Simple Squamous
Which type of epithelial tissue can be found in the collecting tubules of the kidneys, and thyroid follicles?
Simple Cuboidal
What type of epithelial cells is a host to a goblet cell?
Simple columnar Epithelium. Remember that the goblet cells do not stain on the slide, they are easy to see.
The epidermis is primarily composed of ____________ epithelia
stratified squamous (abundant keratin)
What type of epithelial cells would I find in my trachea?
Pseudostratified columnar epithelia
What type of epithelia would I find in the epididymis?
Pseudostratified Columnar with stereocillia.
In the epididymis, what type of cells have highly developed Golgi Apparatus’s?
Principal Cells, and they are the only type of cell to actally reach the lumen.
What ligands do cadherins recognize?
other cadherins
What type of ligands do the selectins recognize?
Carbohydrates
What type of CAMs lock the cell to the matrix?
Integrins (using a hemidesmosome)
The annoying immnoglobulin superfamily recognizes what type of ligands?
integrins
Which type of Cadherins form dimers? (They are also the most common)
E-cadherins
EPITHELIAL
Where might you find epithelia that could form a leaky barrier?
lining of gall bladder
PCT of nephron
What specific type of epithelia offers protection from wear and tear
stratified sqamous epithelia
Stratified Columnar epithelia is rare. Name places you can find it…
- Sweat ducts (adult)
- Fornix of the conjunctiva of the eye
- parts of the male urogenital tract
- pharynx
- epiglottis
What is the difference between an Adherens and Occludens?
Aderens are the molecular complexes that anchor cells together and reinforce the physical integrity of tissues and the cells that make up the tissues.
FOUND: basolateral surfaces
Ocludens are the molecular complexes that establish an impermeable barrier between adjacent cells. PREVENTS paracellular transport and maintains concentration differences, nothing in… nothing out.
Define Gap Junction
make up of molecular pores that allow cells to rapidly exchange ions and other molecules. They help coordinate activities among the cells that make up the tissue.
What are the two types of junctional complexes?
Zonula (adherense or occludens)
and
Macula (spot or snap like junction)
Which type of junction is associated with intracellular intermediate filaments (tonofilaments?)
Macula adherens
Which type of junction is associated with intracellular actin?
Where can you find Desmogein 1 and 2?
Epidermis!
What is the clinical importantce of autoantibodies to desmoglein1?
Autoantibodies to desmoglein 1 result in pemphigus foliaceus… of course
What do Desmoplakin and Plakoglobin have in common?
They are present in the plaques associated with cadherin proteins
Which proteins do the Claudins and occludins attach to inteacellularly?
JAMS and nectin are members of what group?
immunoglobulin superfamily
Tell me about connexons… what are 3 things mentioned in lecture?
- Each connexon consists of 6 connexins, forming hexagonal structure with a hollow center.
- Connexons facilitate movement of molecules up to 1.2 nm in diameter
- Connexons are often clustered into patches.
**Focus on unique components, and how do they tie into the functions of the junction
When do gap junctions close?
Gap junctions close when calcium ion concentrations are high!
What are two clinical isses that arise from pathologies of gap junctions?
Charcot-Marie-Tooth neuropathy
and
Congenital cataracts
