Epithelium

Question 1

Ectoderm Endoderm Mesoderm

Answer 1

Ectoderm: Epithelia of skin / oral mucosa

Endoderm: Epithelium lining the respiratory and digestive tracts

Mesoderm: Epithelium of the urinary tract, inner lining of blood vessels, body cavities

Question 2

lamina propria

Answer 2

any epithelium / connective tissue inside the body

Question 3

What is the basal lamina composed of?

Answer 3

laminins: attach to integrins from cells
type 4 collagen: attaches to laminin network
entactin and perlecan: attach the laminin network to the type 4 collagen.

Question 4

What does reticular lamina contain?

Answer 4

type 3 collagen (reticular fibers)
type 7 collagen links basal lamina to reticular lamina (type 3 + 4 = 7)

Question 5

zonula occludens

Answer 5

tight/occluding junctions
claudin and occluden are the 2 most important proteins forming the junctions
prevents passage of materials between cells.

Question 6

zonula adherens, macula adherens

Answer 6

adhering/anchoring junctions

provide attachment of one cell to another, not as tight as occluding junctions.
completely encircles cell
cadherins: transmembrane glycoproteins, bind to catenin, links to actin.

Question 7

connexons

Answer 7

gap (communicating) junctions

pores surrounded by proteins called connexins.
allow passage of small molecules / ions from one cell to another
rapid communication

examples: cAMP cGMP ions

Question 8

hemidesmosomes

Answer 8

serve as points of attachment of epithelial cells to components of ECM / basal lamina

Question 9

cilia components (and flagella)

Answer 9

axoneme (core) formed of microtubules
dynein causes movement

Question 10

special cases of epithelium

Answer 10

pseudostratified epithelium: all cells attach to basal lamina, not all cells reach surface.
looks like multiple layers of cells but there arent.

urothelium (transitional epithelium): surface cells change shape as tissue stretched.
found only in urinary system