Epidermis

Question 1

describe the structure and function of S. Corneum and S. Lucidum

Answer 1

S. Corneum and S. Lucidum are made of stratified squamous epithelial cells. The stratum corneum is the final product of keratinocytes that are filled with only keratin. The stratum lucidum is only found in thick skin and provides an extra layer of protection to high friction areas.

Question 2

describe the structure and function of Stratum granulosum

Answer 2

Stratum granulosum is about 3-5 layers of dying keratinocytes that become squamous. The keratin fibers become more prominent as the typical cell organelles begin to disappear. Contains lamellar granules that produce lips to diffuse superficially to coat the stratum corneum with a waterproof sealant between keratinocytes

Question 3

describe the structure and function of Stratum spinosum

Answer 3

Stratum spinosum is bounded by desmosomes, giving toughness to the skin. The stratum spinosum contains projections of melanocytes that protect the skin.

Question 4

describe the structure and function of Stratum Basale

Answer 4

Stratum Basale is made of cuboidal or columnar cells and has mitotic power to produce new keratinocytes. Stratum Basale contains melanocytes and Merkel cells for touch reception.

Question 5

What are the 4 major cells are the epidermis composed of and what is their function

Answer 5

Keratinocytes - are protein cells that create the skin, nails, and hair. They die as they migrate superficially.
Langerhans- immune cells
Merkel cell - touch receptor cells
Melanocyte - melanin, gives skin a darker color

Question 6

Within the epidermal layers, contrast cell shape, the function of the keratin present in various keratinocytes & metabolic capacity. Relate the metabolic capacity of each layer to the distance from the S. basale.

Answer 6

Migrating superficially from stratum basale, the keratinocytes become less “alive” and metabolic capacity decreases. The metabolic power of the epidermal layer is proportional to the proximity of the cells to the capillary loops. The closer the cells are to the capillary loops, the more power they have. In the end, the keratinocytes in the stratum corneum are completely dead and only filled with keratin, with the least metabolic power. Also, the cell shape becomes flatter when reaching the stratum granulosum.

Question 7

Be able to answer a complex question like “are the melanocytes of the epidermis found in the S. basale or S. spinosum?”, or “are there 4 or 5 layers to the epidermis”?

Answer 7

The melanocytes are found in the basale layer and their projections are found in the spinosum layer. There are 5 layers to the epidermis if the skin is thick and 4 layers if the skin is thin.

Question 8

Contrast the location & role of thick and thin skin.

Answer 8

Thick skin is found in the fingertips, palms, and soles of the feet, anywhere that has high friction. The stratum lucidum in thick skin allows an extra layer of protection. Thin skin helps prevent infections and allows hair to grow for protection.

Question 9

Be VERY comfortable describing the constant migration of cells basally to apically,
concentrating on the mitotic power of the S. basale.

Answer 9

The basal layer is the innermost layer of the epidermis and contains small round cells called basal cells. The basal cells continually divide, and new cells constantly push older ones up toward the surface of the skin, where they are eventually shed.

Question 10

Name a couple of accessory structures of the dermis that penetrate the epidermis.

Answer 10

The hair follicle and sweat pore