epithelial tissues

What embryonic layer does epithelium originate from?

Ectoderm.

What structures are made of epithelial tissue?

Skin, hair/fur, wool, feathers, claws/nails, scales.

What type of junctions connect epithelial cells?

Tight junctions containing cadherins.

What is the role of cadherins?

Mediate cell-to-cell adhesion.

What is simple epithelium?

A single layer of epithelial cells.

What is stratified epithelium?

Multiple layers of epithelial cells.

What is the name of the replicating skin cells?

Keratinocytes.

Where do skin cells proliferate?

In the basal layer of the epidermis, near the dermis.

What is the function of spinous cells?

They stop proliferating and synthesize keratin networks.

What is the function of granular cells?

They produce lipid granules and cross-link proteins.

What happens in the cornified layer?

Cells lose organelles and metabolic activity, forming a tough barrier.

What proteins do keratinocytes produce?

Keratins, a family of intermediate filament proteins.

How many keratin proteins are in the family?

54

Where are keratins found?

Skin, hair, hooves, horns, cornea, scales.

What is the role of keratin?

Structural support via cross-linking.

Which keratin is expressed in basal cells?

Keratin 14.

Which keratin is expressed in suprabasal layers?

Keratin 10.

What protein promotes proliferation via adhesion to the matrix?

β1 integrin.

What protein inhibits proliferation?

Transforming Growth Factor-β (TGF-β).

What signaling pathway promotes differentiation?

Notch signaling (cell-cell interaction).