Skin

Question 1

Epidermis

Answer 1

Forms major distinction between thick skin (palms and soles, 400 to 1400 micro M) and think skin (75 to 150 micro m)

Lacks vasculature, but recieves nutrients and O2 by diffusion from dermis

Question 2

Layers of Epidermis: Top Down

Answer 2

Stratum Corneum

Stratum Lucidum

Stratum Granulosum

Stratum Spinosum

Stratum Basale

Question 3

Stratum Basale

Answer 3

Intense mitotic activity

Single layer of basophilic cuboidal or columnar cells at basement membrane at dermal epidermal junction

Hemidesmosomes in hte basal cell membranes join these cells to the basal lamina

Desmosomes bind the cells of this layer together in their lateral and upper surfaces

Durring differentiation, cells move upward

Question 4

Stratum Spinosum

Answer 4

Just above the basal layer

Thickest layer, esp in epidermal ridges

Consists of generally polyhedral cells with cenral nuclei

Desmosomes hold the cell layers together

Thick skin subject to continuous friction and pressure (such as the foot soles) has a thicker stratum spinosum

The most basal layer can be involved in repair

Question 5

Stratum Granulosum

Answer 5

Three to five layers flattened cells undergoing the terminal differentiation process of keratinization

Cytoplasm is filled with intensely basophilic masses (called keratohyaline granules and lamellar granules)

Among the last activities of the keratinocytes, the lamellar granules undergo exocytosis, producing a lipid-rich, impermeable layer around the cells

Question 6

Stratum Lucidum

Answer 6

Only in thick skin

Consists of a thin, translucent layer of flattened eosinophilic karatinocytes held together by desmosomes

No nuc or organelles

Cytoplasm constits almost exclusively of packed karatin filaments

Question 7

Stratum Corneum

Answer 7

Consists of 15-20 layers of squamous, karatinized cells

By the end of keratinization, the cells contain only amorphous, fibrillar proteins with plasma membranes surrounded by the lipid rick layer

These fully karatinized cells or cornified cells called SQUAMES are continuously shed at the epidermal surface as the desmosomes and lipid rick cell envelopes break down

Question 8

Squamous cell carcinoma

Answer 8

Stratum spinosum (keratinocytes)

Question 9

Basal Cell Carcinoma

Answer 9

Stratum Basale (basal cells)

Question 10

Melanoma

Answer 10

Stratum Basale (melanocytes)

Question 11

Merkel Cell Carcinoma

Answer 11

Stratum Basale (merkel cells)

Question 12

Friction Blisters

Answer 12

Fluid buildup between epidermis and dermis

Question 13

Hypopigmentation (albinism)

Answer 13

Congenital defect in melanin producing pathway.

Tyrosinase defect.

Final products pheomelanins and eumelanins

Question 14

Eumelanins

Answer 14

Black brown pigment created by melanocyte

Question 15

Pheomelanin

Answer 15

Pigment in red hair

Question 16

Depigmentation (Vitiligo)

Answer 16

Acquired condition with loss of decreased activity of melanocytes

Question 17

Dermis

Answer 17

Connective tissue that supports epidermis

fibroblasts

macrophages

mast cells

other leukocutes

Collagen (I and III)

Elastic fibers

Question 18

Layers of Dermis

Answer 18

Papillary layer ( loose connective tissue)

Reticular layer ( dense irregular connective tissue)

Question 19

Dermatofibroma

Answer 19

arise from fibroblasts/ dendritic cells?

Question 20

Dermatofibrosarcoma Proteburans

Answer 20

Arises from Fibroblasts

Question 21

Hemangioma

Answer 21

Arises from endothelial cells (vessels)

Question 22

Hemangiosarcoma

Answer 22

Arises from enothelial cells (Vessels)