Integument I

Question 1

Epidermis (Epithelium + cells)

Answer 1

Keratinized stratifies squamous
epithelium
Derived from ectoderm

Question 2

Dermis

Answer 2

Dense connective tissue

Derived from mesoderm

Question 3

Hypodermis

Answer 3

-deep to (beneath) the dermis
-ariable amounts of adipose
tissue (panniculus adiposus) arranged
in lobules and separated by
connective tissue septa
-mechanoreceptors in this layer

Question 4

largest cell population

Answer 4

▪ Keratinocytes

Question 5

pigment producing cells

of the epidermis.

Answer 5

Melanocytes

Question 6

• Langerhan’s cells

Answer 6

antigen presenting
cells (APC’s)
• plays a role in the immunological function
of skin
• accounts for 2%-5% of cells

Question 7

Merkel cells

Answer 7

mechanoreceptors
• associated with sensory nerve endings
• constitutes 6%-10% of cells in the
epidermis

Question 8

Keratinocytes-Functions:

Answer 8

Produces keratin (cytokeratin)– mainly
the keratinocytes of stratum basale
• Produce keratohyalin granules – cells
in spinosum and granulosum layers
• Contributes to the formation of the
epidermal water barrier

Question 9

Melanocytes

Answer 9

• Located in the basal layer (stratum basale)

- Originates from neural crest

Question 10

Melanocytes-Functions:

Answer 10

-Produce melanin that is transferred to
surrounding keratinocytes (Cytocrine
secretion)
-Skin color
-Oxidation of tyrosine to 3,4-
dihydroxyphenylalanine (DOPA) and
subsequent transformation of DOPA
into melanin

Question 11

Melanin distribution

Answer 11

Light skinned persons - concentrated in stratum basale

• Dark sinned persons - dispersed throughout stratum basale and spinosum

Question 12

Eumelanin

Answer 12

-Protection against UVR damage
-Scatter and absorb UV rays and eliminate UV-generated
free radicals
-Degrades faster in lighter skinned individuals

Question 13

Pheomelanin

Answer 13

Allows UV

• Found more commonly in atypical nevi and melanomas
• Increased oxidative damage

Question 14

Langerhan’s Cell: Structure

Answer 14

Originates from common lymphoid
progenitor (CLP)
• Present in all epidermal layers but
most easily recognized in stratum
spinosum

Question 15

Langerhan’s Cell:Function

Answer 15

• Immunological role
  -delayed type
  hypersensitivity reactions
  -• Express both MHC 1 and MHC II and
  receptors for IgG

Question 16

Merkel’s Cell: Structure

Answer 16

-Most abundant in skin where sensory
perception is acute
-Merkel’s corpuscle

Question 17

Merkel’s Cell:Function

Answer 17

-Detect touch sensations
-• Have desmosomes and contain
keratin filaments
-Nucleus is lobed
-Cytoplasm contains neurosecretory
granules
-Possess antigenic markers of both
epidermal and neural type

Question 18

Thick Skin

Answer 18

Found only in the palms and soles
• Usually hairless and much thicker
epidermis
• Carries a stratum lucidum

Question 19

Thin Skin

Answer 19

Found everywhere else
• Thinner epidermis than thick skin
• Hair follicles are widespread except for
a few locations

Question 20

Stratum basale

Answer 20

-Can differentiate
-• Single layer of cuboidal to low columnar
cells
-basophilic staining
-Rests on the basal lamina
• Attached by hemidesmosomes

Question 21

Stratum Spinosum (S)

Answer 21

-Maturing and slowly dying cells
-Exhibit numerous cytoplasmic processes or
spines
-• Processes of neighboring cells are connected to each
other via desmosomes
-

Question 22

Bullous pemphigoid

Answer 22

Clinical correlate –Stratum Basale

Question 23

Pemphigus vulgaris

Answer 23

Clinical correlate-Stratum Spinosum

Question 24

Stratum Granulosum

Answer 24

• conspicuous granules
• Keratinization (soft keratin)
• • Lamellar bodies • Epidermal water barrier

Question 25

Stratum Lucidum

Answer 25

Stratum Lucidum

Question 26

Stratum Corneum (SC)

Answer 26

-Several layers of dead keratinocytes
-• Lack organelles
• Thick plasma membranes covered with
lipid forming a barrier that is impermeable
to water (WATER BARRIER)
- Abrupt transition from granulosum

Question 27

Pemphigoid vulgaris

Answer 27

Clinical correlates–Stratum Corneum (SC)

Question 28

Formation of Epithelial Water Barrier-Cell envelope

Answer 28

• Insoluble proteins on inside of cell
membrane
• Mechanical part of barrier

Question 29

Formation of Epithelial Water Barrier-Lipid envelope

Answer 29

Lipid layer on outer surface of the cell
membrane
• Lamellar bodies

Question 30

Epidermal Turnover Time: Normal-Days 1-2

Answer 30

Keratinocytes in stratum
basale divide mitotically
and migrate to stratum
spinosum

Question 31

Epidermal Turnover Time: Normal -Days 3-31

Answer 31

Duration of keratinocytes
stay in stratum spinosum
Later move to granulosum

Question 32

Epidermal Turnover Time: Normal -Days 32-46

Answer 32

Keratinocytes become
keratinized and enter
stratum corneum