Pathophys-Day 1 Skin Functions (Intro to Skin Bio)

Question 1

What is one major histological difference between the dermis and epidermis?

Answer 1

No vasculature in epidermis

Question 2

What cells are found in the epidermis?

Answer 2

Keratinocytes, melanocytes, Langerhands, Merkel

Question 3

What cells are found in the dermis?

Answer 3

Fibroblasts (collagen/elastin), vessels, nerve endings

Question 4

What cells are found in the subcutis?

Answer 4

Fat and vessels, fibrous septae

Question 5

Describe the epidermal cell cycle

Answer 5

Sheds every ~28 days; stem cells in basal layer rise to surface as they differentiate; cycle ends in apoptosis in the epidermis

Question 6

What are the four layers of the epidermis?

Answer 6

Stratum basale/basal cell layer
Stratum spinosum/spiny layer
Stratum granulosum/granular layer
Stratum corneum

BSGC

Question 7

Describe the S&F of basal layer

Answer 7

Source of stem cells

Basal cells adhere to dermis basement membrane via HEMIDESMOSOMES (disorder: bullous pemphigoid)

Question 8

Describe the S&F of spinous layer

Answer 8

Cell division ends and terminal differentiation begins

Lamellar granules develop lipids responsible for water-tight barrier (not released yet)

‘Spiny’ because of inter-keratinocyte DESMOSOMES

Question 9

Describe the S&F of granular cell layer

Answer 9

Keratohyaline granules synthesized here including profilaggrin

Lamellar granule lipids secreted into IC space to form water barrier

Question 10

Describe the S&F of stratum corneum

Answer 10

Nuclei/organelles degenerate, cells flatten
Profilaggrin->filaggrin (keep water in cells-hydration)
Keratins combine with filaggrin into macrofibrils creating protective barrier

Question 11

Where is the stratum corneum thickest?

Answer 11

Palms, etc

Question 12

Explain the brick and mortar comparison of the stratum corneum

Answer 12

Bricks: flat keratinocytes filled with keratin and filaggrin
Mortar: lipid mixture around keratinocytes provide water barrier

Question 13

Keratins are a type of __ that contain __ as part of their structure

Answer 13

Intermediate filaments; sulfur/cysteine

Question 14

Describe melanocytes

Answer 14

Pigment-producing
Derived from neural crest cells
Live along basal cell layer 1:10 keratinocytes
Transfer melanin to surrounding k'cytes
Dendritic arms

Question 15

Describe langerhans cells

Answer 15

dendritic cells in mid-epidermis
antigen-presenting; migrate to lymph nodes
allergic reactions and tumor surveillance

Question 16

Compare the location of langerhans cells and melanocytes

Answer 16

Langerhans are higher up - mid-epidermis

Melanocytes lower closer to dermis

Question 17

Merkel cells

Answer 17

Light touch sensation receptors at the bottom of the epidermis

Question 18

What does the dermis contain?

Answer 18

Vessels, lymphatics, nerves, sweat and oil glands, hair follicles

Question 19

What does the pilosebaceous unit contain?

Answer 19

Hair follicle
Oil gland
Apocrine sweat glands (axilla, anogenital)
Arrector pili

Question 20

Which sweat glands are NOT associated with a follicle?

Answer 20

Eccrine - true sweat glands

Question 21

Genetic defects in flaggrin cause __

Answer 21

atopic dermatitis

Question 22

Mutations in Keratins 5 & 14 cause __

Answer 22

epidermolysis bullosa simplex

Question 23

Epidermolysis bullosa simplex arises from this genetic defect

Answer 23

Keratins 5 & 14

Question 24

Where does the blister form in epidermolysis bullosa complex?

Answer 24

Within the basal keratinocyte due to loss of ability of keratins to keep contents close to hemidesmosome barrier

Question 25

Albinism is a disease of which layer

Answer 25

Epidermis (melanocytes)