Epidermis

ORG: Integumentary system CH

Three main layers of skin are?

• Epidermis - outermost layer (Five layers)

• Dermis - Middle layer (Two layers)

• Subcutaneous Tissue/Hypodermis - The innermost layer.

Epidermis

The most superficial layer of skin composed of five layers or strata.

Stratum Basale (Basal layer)

The deepest layer of the epidermis, responsible for the production of keratinocytes and contains melanocytes. It also has rapid cell division.

Keratinocytes

Cells produced in the stratum basale that are key to the formation of the epidermis.

Melanocytes

Cells that produce melanin, which determines skin color.

Stratum Spinosum

Sits above the stratum basale, fourth strata, characterized by desmosomes and containing Langerhans cells.

Desmosomes

Structures that connect two cells together, giving the Spinosum layer its spiny appearance.

Langerhans cells

Immune cells present in the stratum spinosum that engulf foreign invaders.

Stratum Granulosum

Layer of the epidermis above the stratum spinosum, third strata, named for keratohyalin granules present in keratinocytes and being able to release lamellar bodies.

Keratohyalin granules

Protein-containing granules in keratinocytes that handle keratin.

Lamellar bodies

Structures that release lipids, forming a water-tight layer at the skin's surface in the stratum granulosum.

Stratum Lucidum

The second layer under the corneum. A clear layer of dead keratinocytes that lacks nuclei and organelles.

Zombie keratinocytes

Term used to describe the keratinocytes in the stratum lucidum.

Stratum Corneum

The topmost layer of the epidermis composed of stacked layers of dead keratinocytes.

Reptilian molting

The process reptiles use to shed the entire stratum corneum layer in one piece.