General Histology

Question 1

Claudins

Answer 1

Transmembrane proteins that can act as channels for small molecules (paracellular)

Question 1

Occludin

Answer 1

transmembrane protein, function not clear

Question 2

Junctional adhesion molecules:

Answer 2

(JAM) transmembrane protein that may mediate permeability to larger molecules

Question 3

ZO-proteins

Answer 3

Interact with cytoskeleton in tight junction formations.

Question 4

Tight junctions:

Answer 4

keep basolateral and apical cell membrane components separated.

Question 5

Adherin junctions:

Answer 5

found immediately below tight junctions

strengthens and stabalizes tight junctions

Participates in cell-cell signaling (regulates cell division and proliferation)

Question 6

Key Adherin proteins and their functions:

Answer 6

Cadherin: transmembrane protein that interacts with other adherins on neighboring cells

Catenins: linker molecules that connect the intracellular face of claudins to the actin cytoskeleton

Question 7

Desmosomes:

Answer 7

only attach to certain spots of the epithelial cell membrane

Question 8

Desmosomes and adherins similarities:

Answer 8

strong adhesion between cells

Use cadherin-like molecules

Both have intracellular plaques that interact with proteins that can act as signalers and linkers.

Question 9

Desmosomes and adherin differences:

Answer 9

Desmosomes conect to intracellular intermediate filaments

Desmosomes provide more structural stability to the cell

Question 10

Hemidesmosomes:

Answer 10

Intigrin as “linking protein”

Does not bind to molecule on adjacent cell

adhesion of epithelial cell to the basement membrane

Question 11

Tight junctions:

Answer 11

claudins and JAM transmembrane proteins

extens to extracellular space to bind to claudins and JAMs on neighboring cells

ZO proteins bind to the intracellular face of claudins and JAMs, linking them to actin cytoskeleton underneath

Cell membrane proteins, even lipids seem unable to cross the “belt” of the TJs.

Located in apical aspect of the epithelial cells

Barrier that prevents movement of undesirable substances to the tissues below

regulates the movement of a variety of molecules between cells, through the barrier

helps establish polarity

Question 12

Type II collagen:

Answer 12

smaller fibrils with less organized orientation than dense regular tissue (major component of cartilage)

Question 13

Type III collagen:

Answer 13

reticular fibers (major component of loose connective tissue)

Question 14

Type I, II, III collagen:

Answer 14

fibrillar collagens

Question 15

Type IV collagen:

Answer 15

forms the basement membrane that connects epithelial and connective tissue layers (cross-linked “net” with glycoproteins (laminin) and proteoglycans interspersed within it

Question 16

Multiadhesive glycoproteins:

Answer 16

These bind to a wide variety of components of the extracellular matrix

Question 17

Proteoglycans:

Answer 17

A very long, linear polymer of hyaluronic acid (GAG)

linking proteins attached to the hyuralonic acid polymer

shorter GAG chains attached to the linking proteins

Highly hydrated “collect” water n the ECM

Store growth factors

Question 18

Keratin:

Answer 18

main intermediate filament in keratinocytes

Strong and forms bundles: a barrier that prevents water loss from deeper layers and microbe invasion

complexes with another protein: flaggrin that helps compact eratin and attracts water, aiding in skin moisturization

Question 19

Atopic dermatitis:

Answer 19

One of the most common skin conditions.

Typically begins in childhood 10-30% of children affected

Becomes less common with age 2-10% of adults

Signs and symptoms:
-itchy papules and plaques that can become excoriated with scratching

-distributed over the exterior surfaces, face, and scalp

-Worse in response to allergen exposure

Question 20

Paracellular route ______ adjacent enterocytes: mostly regulated by tight junctions

Answer 20

between

Question 21

Transcellular route _________enterocytes, across cell membranes, regulated by membrane proteins

Answer 21

through

Question 22

Celiac disease:

Answer 22

common immune-mediated disorder: imune response to a component of gluten (gliadin)

present in wheat, barley, rye

Inflammatory response damages the delicate structure of the villus