INTRO TO DERM Flashcards
functions of skin
protection thermoregulation excretion of waste water homeostasis nutrition, vit D communication
tools used in derma?
biopsy dermatoscope patch testing ultrasound mineral oil potassium hydroxide confocal microscopy
first weeks of life, fetus covered in? replaced by? when do the adnexae develop?
periderm, epidermis
3rd month of fetal life
basal layer cells?
keratinocytes
melanocytes
melanosomes
merkel cells
○ 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?
Keratinocytes
○ 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?
Melanocytes
- 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?
Melanosomes
- 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?
Merkel cells
what are the spinous layer cells?
keratinocytes
langerhans cells
what cells are found in the granular cell layer?
keratinocytes
keratohyaline granules
these cells of the spinous layer are antigen presentation?
langerhan cells
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?
keratinocytes
● 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?
Keratohyaline granules
what is found in the cornfield layer?
keratinization
proteins
lipids
what are the intercellular junctions?
adherens junctions
tight junction
gap junctions
what are the adnexal structures?
originate as down growths from epidermis or hair follicle
source of stem cells for epidermal repair
*eccrine glands, apocrine glands, sebaceous glands, hair follicle
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
Eccrine Glands
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
Apocrine glands
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
Sebaceous glands
hair follicle is comprised of?
infundibulum isthmus bulge lower follicle bulb
