Lecture 2: Epithelium Tissue Flashcards
(113 cards)
what major tissue
- covers body surface
- lines hollow internal organs, cavities, ducts
- forms glands of body
epithelial tissue
x3 categories of function of the epithelium tissue?
Selective barriers = limit/aid transfer
secretory = onto a free surface
protective = from abrasion, external entry from exterior
x2 structural features of epithelium cells
(arrangement and held together)
- Arranged in continuous sheets: single or multi layered
- Held together by cell junctions: adherens, tight, gap, desmosomes, hemidesmosomes
What are the different surfaces of epithelial cells
Apical surface > environment exposure side
lateral surface
basal surface > internal exposure side
types of junctions in the lateral surface…
Tight junctions
Adherens junction
Gap junctions
Desmosomes
What junction is in the basal junction?
Hemidesomosomes
purpose of the cytoskeleton
provide cell skeleton to maintain structure + shape
x2 cytoskeleton components
- Microfilaments
- Intermediate filaments
x2 functions of the microfilaments
- link cells together
- generate force in cellular contraction and basic cell movements
Protein that makes up microfilaments?
Actin
Protein that makes up intermediate filaments?
many different proteins; Keratin
x3 functions of intermediate filaments
- cell cohesion and prevent acute fracture of cell sheet under tension
- structure
- path for material to move through cytoplasm (train track system)
are the intermediate filaments thicker/less flexible or thinner/flexible than microfilaments?
intermediate filaments thicker and less flexible
tight junctions are electrically tight… what does this mean?
ions can’t get down in between cells
- can keep x2 separate environments
what proteins in tight junctions “traverse membranes to weld + hold adjacent cells together”
Claudins
Occludins
function of the Claudia and Occluding proteins
- join cytoskeleton to actin
- maintain polarity of cell by preventing migration of proteins between apical and basal surfaces
Where are tight junctions found?
stomach
intestines
bladder
what type of junction contains “web-like transmembrane that fuse together surfaces of adjacent cells”
tight junctions
x2 main functions of tight junctions?
- inhibit passage of substance between cells
- prevent leakages
true or false
the adherens junctions are more apical located than tight junctions
FALSE
adherens junctions are more basal located
Why adherens junctions have a plaque layer of proteins inside cell
join actin (microfilaments) to cadherins (cytoskeleton)
glycoprotein that spans gap between adjacent cells in adherens junctions
cadherins
what is a type of cytoplasmic contractile protein
actin
What links cadherins to actin?
(cell cytoplasm to microfilaments)
Catenins