Epidermis

Question 1

functions of skin

Answer 1

maintenance of body temperature, recognition of outer environment, defense against microorganisms, protection from harmful materials in external environment

Question 2

defensive functions classifications?

Answer 2

physical, thermal, immune, UV, oxidant, antimicrobial, permeability barrier

Question 3

epidermis derivation?

Answer 3

ectoderm

Question 4

layers of epidermis

Answer 4

4. 5th (translucent layer, stratum lucidum) present between granular layer and cornified layer on palms and soles

Question 5

4 layers?

Answer 5

basal layer, spinous layer, granular layer, cornified layer

Question 6

basal layer?

Answer 6

bottom, attached to basement membrane. contains stem cells

Question 7

basal layer stem cell process?

Answer 7

stem cells divide into daughter + transient amplifying cell. TAC divides more before separating up into stratum spinosum

Question 8

stratum spinosum contents

Answer 8

(spinous layer) contains most of keratinocytes of skin, held together by desmosomes.

Question 9

desmosomes are?

Answer 9

Desmosomes are protein complexes that connect keratinocytes and their keratin intermediate filament network

Question 10

other things responsible for keratinocyte communication and adhesion

Answer 10

Gap junctions, adherens junctions and tight junctions

Question 11

what are keratins?

Answer 11

α-helical proteins that make up the intermediate filaments of the skin. Keratins are divided into type I (acidic) and type II (basic) keratins. they heterodimerize.

Question 12

keratin intermediate filament formation?

Answer 12

2 heterodimers form a tetramer, further organized into protofilaments then keratin intermediate filaments. Keratin intermediate filaments connect to desmosomes and hemidesmosomes to form the cytoskeleton network of the epidermis

Question 13

what is the granular layer composed of?

Answer 13

(stratum spinosum) composed of flattened keratinocytes, starting to lose their nucleus and cell organelles. named this because of keratohyaline granules and lamellar granules that are present within and secreted by the keratinocytes

Question 14

what are Keratohyalin granules?

Answer 14

filled with proteins that are important for formation of the cornified envelope, such as profilaggrin

Question 15

where are lamellar granules?

Answer 15

present in the upper layers of the spinous layer but not secreted until the granular layer

Question 16

what are in lamellar granules?

Answer 16

granules contain lipids such as ceramides and cholesterol that are important in forming the lipid barrier of the cornified layer. In addition, lamellar granules contain hydrolytic enzymes that promote desquamation of the cornified layer.

Question 17

what is the cornified layer made of?

Answer 17

anucleate cells called corneocytes

Question 18

what are corneocytes made of?

Answer 18

held together by proteins (e.g. filaggrin) and lipids (e.g. ceramides) released by the keratohyalin and lamellar granules, respectively

Question 19

other cells in basal layer?

Answer 19

melanocytes

Question 20

what and where are langerhans cells found?

Answer 20

type of antigen-presenting immune cell localized to the skin. spinous layer and can be present throughout the epidermis and dermis

Question 21

what is keratinization?

Answer 21

also called cornification. it is the process of keratinocyte migration and maturation.

Question 22

process of keratinization?

Answer 22

1. differentiation of the stem cell into a keratinocyte and separation from the basement membrane. 2. As the keratinocyte migrates to the skin surface, it flattens out and loses its water content. Lamellar granules and keratohyaline granules start to form. 3. keratinocyte progressively loses its cellular organelles and nucleus, and releases its intracellular granules. 4. The keratinocyte becomes an anucleate corneocyte within the cornified envelope and is eventually shed in the process of desquamation

Question 23

transit time of a keratinocyte through the epidermis

Answer 23

28 days

Question 24

days to migrate from the basal layer to the granular layer?

Answer 24

14

Question 25

corneocyte spends how many days in the cornified layer before desquamating?

Answer 25

14

Question 26

what is the cornified envelope made of?

Answer 26

corneocytes, proteins and lipids

Question 27

what is the protein envelope made of?

Answer 27

filaggrin, which is processed from profilaggrin, and involucrin. other proteins include periplakin and envoplakin

Question 28

what is lipid envelope made of?

Answer 28

ceramide. other lipids include free fatty acids and sterols

Question 29

what is pemphigus vulgaris?

Answer 29

autoimmune blistering disease. It is a rare disease, affecting mainly elderly people of all races and both sexes

Question 30

what is the cause of pemphigus vulgaris?

Answer 30

autoantibodies against desmosomal proteins, specifically desmoglein 1 and 3. get weakened desmosomes, intraepidermal blistering occurs.

Question 31

symptoms of pemphigus vulgaris?

Answer 31

flaccid blisters that quickly turn into erosions. can affect mucosal sites such as the mouth, nose, and genitalia, as well as any cutaneous site on the body. It can be fatal, especially when not treated

Question 32

treatment of pemphigus vulgaris?

Answer 32

flaccid blisters that quickly turn into erosions. Pemphigus vulgaris can affect mucosal sites such as the mouth, nose, and genitalia, as well as any cutaneous site on the body. It can be fatal, especially when not treated

Question 33

Ichthyosis vulgaris is?

Answer 33

common autosomal dominant genetic condition with widely variable expression.

Question 34

Ichthyosis vulgaris is caused by?

Answer 34

mutations in the profilaggrin gene that lead to a defective cornified envelope

Question 35

symptoms of ichthyosis vulgaris?

Answer 35

large scales on the body. The extremities, primarily the shins, are preferentially affected. Patients have extremely dry skin and hyperlinear palms.

Question 36

Ichthyosis vulgaris predisposes to and is associated with?

Answer 36

atopic dermatitis, allergic rhinitis, food allergies, and asthma

Question 37

3 groups of UV light are?

Answer 37

UVC: 200-280 nm UVB: 280-320 nm UVA: 320-400 nm

Question 38

UVC light?

Answer 38

absorbed by the ozone layer and very little of it reaches the earth’s surface

Question 39

UVB light?

Answer 39

penetrates the epidermis and superficial dermis of the skin

Question 40

UVA light?

Answer 40

makes up most of the sun’s radiation that reaches the earth’s surface and penetrates into the dermis

Question 41

primarily responsible for erythema and sunburn?

Answer 41

UVB

Question 42

tanning and photoaging?

Answer 42

UVA

Question 43

UV light = carcinogen promoting?

Answer 43

skin cancers such as basal cell carcinoma, squamous cell carcinoma, and melanoma

Question 44

role for UV phototherapy?

Answer 44

used to treat many skin diseases such as psoriasis, atopic dermatitis, and mycosis fungoides

Question 45

sunscreen contains?

Answer 45

physical blockers or chemical blockers

Question 46

chemical blockers?

Answer 46

absorb UV radiation and convert it into heat. ex: PABA, avobenzone (Parsol 1789), oxybenzone, cinnamates, and salicylates. some are photolabile.

Question 47

SPF measures?

Answer 47

provides a measure of the protection against UVB exposure and sunburns but does not measure UVA protection.

Question 48

Minimal erythema dose is?

Answer 48

the minimum amount of UVB that causes skin redness at 24 hours

Question 49

SPF is (mathematicall)

Answer 49

ratio of the MED when protected by the sunscreen compared to the MED when unprotected (SPF = MED protected/MED unprotected)

Question 50

sunscreen criteria?

Answer 50

Patients should look for broad spectrum sunscreens that are at least SPF 30. applied at least 15 minutes prior to sun exposure so that it may properly absorb into the skin. 1 oz per adult body. Reapplication of the sunscreen every 2 hours.