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Flashcards in Structure and Function of skin Deck (23):

The developmental growth pattern of skin follow which lines?

Blashcko's lines (not following any nerves, vessels or lymphatics)


What are melanocytes and where do they migrate from?

Pigment producing cells from the neural crest.


95% of the epidermis is made up of what cells?

Keratinocytes, they contain structural keratins


What type of epithelium is the epidermis?

Stratified squamous


What are the 4 epidermal cell layers?

Basal Layer (Deep)
Prickle cell layer
Granular Layer
Keratin layer (Superficial)


What is meant by differentiation?

Keratinocytes migrating from the basement membrane, this takes 28 days. Continuously regenerates the epidermis.


Describe the basal layer

Usually one cell thick, small and cuboidal.
Lots of intermediate filaments (keratin)
Highly metabolically active.


Describe the prickle cell layer

Larger Polyhedral cells (think P for Prickle, P for Polyhedral)
Lots of desmosomes (connections)
Intermediate filaments connect to desmosomes


Describe the granular layer

2-3 layers of flatter cells
Large keratohyalin granules – contain structural filaggrin & involucrin proteins
Odland bodies (lamellar bodies)
High lipid content
Origin of “cornified envelope”
Cell nuclei lost


Describe the keratin layer

Corneocytes (overlapping non-nucleated cell remnants)
Insoluble cornified envelope
80% keratin & filaggrin
Lamellar granules release lipid
Tight waterproof barrier



Migrate from the epidermis to neural crest in first 3 months of foetal development
basal layer and above
pigment producing dendritic cells


What is Nelson's Syndrome?

A disorder where melanin stimulating hormone is produced in excess by the pituitary (resulting in far darker than expected skin)


What layer are Langerhan's cells found?

Prickle cell layer in epidermis


What do langerhans cells do?

They are antigen presenting cells that pick up antigens in the skin and circulate them to the lymph nodes via the lymphatic system.


Phases of hair growth, what is anagen, catagen and telogen?

anagen = growing
catagen = involuting
telogen = resting


What is the dermo-epidermal junction?

It is an interface between the epidermis and dermis. It holds a key role in epithelial-meschymal interactions e.g.:

-support, anchorage, adhesion, growth and differentiation of epidermal cells.
- it is a semi permeable membrane that acts as a barrier and a filter.


Cells in the dermis:

Fibroblasts: secrete collagen

Macrophages: scavengers, antigen presentation

Lymphocytes: immune reactions

Langerhans cells (also in epidermis): antigen presentation

Mast cells: chemical messengers


What is the most important structure in the skin that determines drug penetrance?

Stratum corneum


Tuberous Sclerosis

- One of the most common genodermatoses
- May present as infantile seizures
- Earliest sign is the ash leaf macule
- Autosomal Dominant
- It is the next most common genodermatosis after NF type 1

- Depigmented macule found in 90% of tuberous sclerosis

- Other skin signs are shagreen patches and enamel pitting.


Epidermolysis Bullosa:

3 types: simple, junctional and dystrophic
- Dominant, recessive, new mutation or acquired.
- Variable severity - blistering at birth does not determine prognosis


Features of Neurofibromatosis Type 1:

Café au lait
Plexiform neuroma - diffuse
Axillary or inguinal freckling
Optic glioma
2 or more Lisch nodules
A distinctive bony lesion


Eczema is a complex disease, describe some of the genetic factors:

Filaggrin (a skin barrier gene, mutations are common approx 1 in 10)
IL-4 and IL-13


Eczema Hepeticum

Monomorphic punched out lesions