Epidermis - created from Mind Map

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Consists mainly of squamous keratinized epithelium, also: Melanocytes; Langerhans cells and Merkel's cells.

consists of 5 layers of keratin producing cells

1. Stratum Basale-

have keratin filaments

Filaments has role in maintaining cohesion among the cells and in resisting the effects of abrasion.

number of filaments increase as they move upwards

characterized my intense mitotic activity and is responsible for constant renewal of epidermal cells.

2 layers = Malpighian layer

2. Stratum spinosum

spine-studded appearance

Filaments NB role in maintaining cohesion among the cells and in resisting the effects of abrasion

Area exposed to more friction = thicker stratum spinosum

cytoplasm displays membrane coating granules=lamellar bodies (lamellar disks) formed by lipid bilayers

3. Stratum Granulosum

Granules not surrounded by membranes

Granules contain:

Lamellar bodies increase in size

Granules discharge contents into ICS-deposited in form of sheets containing lipid

- Profilaggrin

- Involucrin

- Small-proline rich protein

- Loricrin

Function: acts as water barrier as a barrier to penetration of foreign materials

4. Stratum lucidum

Thick skin &stranslucent

no organelles and nucleus

Desmosomes still evident between adjacent cells.

5. Stratum Corneum

contains keratin and amorfous proteins (thick plasma membrane =horny cells

cells are continuously shed at the surface of this layer

Epidermis