skin

Question 1

stratified squamous epithilum is composed mainly of?

Answer 1

cells called keratinocytes

Question 2

melanin is _____ abundant in thick skin

Answer 2

less

Question 3

what are the 3 sections of skin?

Answer 3

-layers of skin, specialized cells & dermal structures and appendages

Question 4

in Thick skin, what is the hydrophobic lipid envelope called?

Answer 4

S. Granulosum

Question 5

In Thick skin, what layer has a translucent appearance?

Answer 5

S. Lucidum

Question 6

In Thick Skin, what layer does keratinization begin?

Answer 6

S. Spinosum

Question 7

In Thick skin, in what layer are stem cells located?

Answer 7

S. basale

Question 8

what is the deepest layer in the skin?

Answer 8

Stratum Basale

Question 9

what stimulates mitosis in S. Basale

Answer 9

molecules from underlying dermis like keratinocyte growth factor, fibroblast growth factor

Question 10

what inhibits mitosis in S. Basale?

Answer 10

Inhibited by retinoic acid; retinoic acid increases the rate of cell differentiation leading to a thinner skin

Question 11

Which layer is directly connected to basement membrane?

Answer 11

Stratum Basale

Question 12

which structures directly attach cells to the basement membrane?

Answer 12

Hemidesmosomes

Question 13

what is the term used to describe a defect in the anchoring of epidermis and dermis

Answer 13

Epidermolysis Bullosa

Question 14

Where are “Spiny cells” found?

Answer 14

S. Spinosum

Question 15

Where are Keratohyaline granules found?

Answer 15

S. Granulosum

Question 16

what are Keratohyaline granules?

Answer 16

they form dense cytoplasmic granules that promote dehydration of the cell as well as aggregation and cross-linking of the keratin fibers

Question 17

what precursor is held in keratohyaline granules

Answer 17

aggregations of high basophilic protein precursor called profilaggrin
- filaggrin corsslinks keratin

Question 18

When are phosphate groups removed from profilaggrin?

Answer 18

AFTER it is cleaved into Filaggrin; prior to this it is highly phosphorylated

Question 19

What are the “waterproofing” structures? where are they found?

Answer 19

Lamellar Bodies found in Stratum Granulosum; lipid-rich secretion is expelled from lamellar bodis that helps waterproof the skin

Question 20

what helps to stabilize the cell membrane of the dead keratinocyte? Where is it synthesized?

Answer 20

Involucrin; synthesized in Stratum spinosum

Question 21

What are melanocytes?

Answer 21

melanin producing cells found in the basal layer of skin

Question 22

What happens to melanosomes?

Answer 22

they are produced by melanocytes and are phagocytized by kerationcytes

Question 23

how do melanocytes protect DNA

Answer 23

melanin produced absorbs UV light to prevent damage to DNA

Question 24

where are melanosomes degraded?

Answer 24

they are degraded in the upper layers of skin by lysosomes

Question 25

what happens to MSH after exposure to UV light?

Answer 25

MSH is induced by UV light; increase in mRNA

Question 26

What are Langerhans cells? where are they found?

Answer 26

``` dendritic cells (antigen-presenting immune cells) containing large granules called Birbeck granules. They are found in all layers but most prominent in S. Spinosum. They actively migrate between keratinocytes to exit the epidermis and reach lymph nodes ```

Question 27

What are Birbeck granules

Answer 27

endosomes specialized for phagocytosis

Question 28

what are Merkel cells?

Answer 28

oval receptor cells associate with the sense of light touch; determination of shapes and textures. found in the basal layer

Question 29

what are Eccrine Sweat Glands?

Answer 29

major Sweat Glands of the body; found in virtually all skin; highest density in palms and soles

Question 30

what is the purpose of myoepithelial cells

Answer 30

they contract and expel the secretions of exocrine glands

Question 31

What are the layers that make up Eccrine sweat gland?

Answer 31

Dark cells, clear cells, and myoepithelial cells

Question 32

what is the purpose of dark cells?

Answer 32

they secrete an antibacterial protin called DERMICIDIN

Question 33

What is the purpose of clear cells?

Answer 33

they transposrt Na, Cl and H2O towards the lumen

Question 34

describe the pathway of the transport of sweat

Answer 34

carried from eccrine glands into the epidermis; transported in a spiraling cavity between keratinocytes that terminates upon the surface.

Question 35

Where are apocrine sweat glands found?

Answer 35

found only in certain locations of the body: the Axillae (armpit), areola and nipples of the breast, ear canal, eyelids and some part of the external genitalia

Question 36

What happens to the secretory material of Apocrine cells?

Answer 36

transformed into pheromones.

Question 37

what are sebaceous glands? where are they found?

Answer 37

they are exocrine glands, with holocrine mode of secretion, that secrete an oily or way substance called sebum. Found in the greatest number on the face and scalp; not on palms of the hands and soles of the feet

Question 38

what is the purpose of sebum

Answer 38

to lubricate and waterproof the skin

Question 39

how to sebaceous glands die?

Answer 39

via apoptosis and burst, releasing lipids into the hair follicle

Question 40

What are found in the epidermis?

Answer 40

``` S. Croneum S. Granulosum S. Spinosum S. Basale keratinocytes langerhans cells Melanocytes ```

Question 41

What is found in the dermis?

Answer 41

reticular and papilary layers

Question 42

what is found in the hypodermis?

Answer 42

epidermal appendages: hair sebaceous glands, apocrine sweat glands, eccrine sweat glands, pacinian corpuscles and Meissner's corpuscles