INTRO TO DERM

Question 1

functions of skin

Answer 1

protection
thermoregulation
excretion of waste
water homeostasis
nutrition, vit D
communication

Question 2

tools used in derma?

Answer 2

biopsy
dermatoscope
patch testing
ultrasound
mineral oil
potassium hydroxide
confocal microscopy

Question 3

first weeks of life, fetus covered in? replaced by? when do the adnexae develop?

Answer 3

periderm, epidermis

3rd month of fetal life

Question 4

basal layer cells?

Answer 4

keratinocytes
melanocytes
melanosomes
merkel cells

Question 5

○ Ectodermal origin
○ Anchored to adjacent keratinocytes via
desmosomes and to BM via hemidesmosomes
(more on this later)
○ Basal layer = site of mitosis

basal layer cell?

Answer 5

Keratinocytes

Question 6

○ From neural crest; in fetal epidermis by 8th week
○ 1 of 10 cells along basal layer
○ can approach 1:1 in heavily sun-damaged facial skin
○ Lack desmosomes (clear halo artifact on H&E)
○ Long dendrite processes to keratinocytes (~36)

basal layer cell?

Answer 6

Melanocytes

Question 7

• lysosomal-related organelles
• Tyrosinase (Cu dependent) is the key enzyme in melanin production, which is primarily regulated by MC1-R
• Loss of function of MC1-R = red heads
• Different number, size, & distribution of melanosomes in different skin types

basal layer cell?

Answer 7

Melanosomes

Question 8

• Found on palms, soles, oral and genital mucosa, nail bed
• Slow adapting touch receptors
• Unclear if Merkel cell carcinoma (trabecular carcinoma) comes from these cells

basal layer cell?

Answer 8

Merkel cells

Question 9

what are the spinous layer cells?

Answer 9

keratinocytes

langerhans cells

Question 10

what cells are found in the granular cell layer?

Answer 10

keratinocytes

keratohyaline granules

Question 11

these cells of the spinous layer are antigen presentation?

Answer 11

langerhan cells

Question 12

As these cells move upward: flatten and start to lose nuclei

Lamellar granules / Odland bodies (also in upper spinous layer)
■ Secreted by keratinocytes into intercellular space
■ Contain loricrin, the most abundant protein in corneum
■ Lipid-rich organelles; contents secreted in granular-corneal interface
■ Triglyceride most abundant lipid in sebum
■ Contributes to barrier to water loss/impermeability and skin cohesion

granular cell layer type?

Answer 12

keratinocytes

Question 13

● Filaggrin aggregates keratin
● Hygroscopic - repeated hydration and dehydration contribute to normal
desquamation of S. corneum
● Ichthyosis vulgaris (profilaggrin mutation) has diminished or absent granular
layer
● Result in formation of soft, flexible keratin
● Keratin formed in absence of these granules is hard and rigid as in
nails and hair

granular cell layer type?

Answer 13

Keratohyaline granules

Question 14

what is found in the cornfield layer?

Answer 14

keratinization
proteins
lipids

Question 15

what are the intercellular junctions?

Answer 15

adherens junctions
tight junction
gap junctions

Question 16

what are the adnexal structures?

Answer 16

originate as down growths from epidermis or hair follicle

source of stem cells for epidermal repair

*eccrine glands, apocrine glands, sebaceous glands, hair follicle

Question 17

what is this adnexal structure?

● Thermoregulatory function
● Sympathetic Cholinergic (acetylcholine) innervation
● Heat is primary stimulus; also emotional stress
● Located everywhere, more on palms/soles, axillae, forehead
● Composed of 3 sections (from top to bottom)
● Duct cells resorb sodium to take sweat from isotonic to hypotonic when reaching
skin surface (varies based on rate of sweating: faster sweating = less hypotonic)
● Composition similar to plasma

Answer 17

Eccrine Glands

Question 18

what is this adnexal structure?

● Develop from upper portion (infundibulum) of follicular epithelium
● Sympathetic Cholinergic and Adrenergic innervation
● Axillae, anogenital area, areola, eyelids (Glands of Moll), external auditory canal
(ceruminous glands), mammary glands
● Structure
○ Straight excretory portion of duct opens into follicular infundibulum (above sebaceous duct)
○ Coiled secretory gland at jxn of dermis and SQ fat
● Decapitation secretion (portion of cells breaks off)
○ Viscous, protein and carbohydrate rich sweat
● Odorless until interaction with surface bacteria
● Excretion is episodic; gland secretion is continuous
● Secretion serves no known function in humans

Answer 18

Apocrine glands

Question 19

what is this adnexal structure?

● Develop from middle of follicle
● Everywhere except palms and soles
● Most abundant on face and scalp
● Always a/w hair follicle except:
■ Meibomian glands (eyelids, tarsal plate)
○Fordyce’s spots (buccal mucosa and vermillion border of lip)
○Tyson’s glands (male prepuce)
○Montgomery’s tubercles (female areola)
○Labia minora
● Lipid mixture + protein, including anti-microbials

Answer 19

Sebaceous glands

Question 20

hair follicle is comprised of?

Answer 20

infundibulum
isthmus
bulge
lower follicle
bulb