Biology of the skin Flashcards
What are the two anatomical compartments of the skin?
Epidermis (50-100 micrometres thick)
Dermis (1000-1250 micrometres thick)
What types of cells are present in the epidermis?
Keratinocyte, fibroblast, Langerhans, melanocytes, Merkle cells
What are keratinocytes?
Produce keratins
What are fibroblasts?
Mesenchymal derived cells, production and remodelling of the extracellular protein collagen
What are Langerhans cells?
Bone marrow derived macrophages
What is the structure of the epidermis?
Epidermis= stratified squamous epithelium
Deep to superficial=
-Basal layer (sits on basement membrane, long term proliferation of stem cells) (basal cells are cuboidal keratinocytes)
-Spindle cell layer/ prickle cell layer (differentiate, keratin proteins, fats and lipids, tight desmosomal attachments between cells)
-Granular cell layer (aggregations of proteins and lipids as granules)
-Stratum cell layer= horny cell layer (bricks and mortar, hydrophobic dead cells impermeable barrier to water, desmosomes are glue no nuclei, flattened keratocytes)
What are appendageal structures?
Hair follicles, sebaceous glands, (together= pilosebaceous gland) eccrine glands, apocrine glands- epidermal derived structures arise during embryonic developments
What are the classes of melanin?
Eumelanin= brown/black (better at blocking UV)
Pheomelanin= red/ yellow
Protect interfollicular skin against UV radiation- melanin cap to protect nucleus, cluster where light comes in
How does UV radiation cause cancer?
Shorter wavelengths more potent, DNA damage, defect in repair of UVR induced DNA damage= Xeroderma pigmentosa, UV carcinogen, 10^26 photons hit face
Why are there red heads if pheomelanin is less effective in blocking UV?
Keratinocytes synthesises vitamin D using UVR so lack of vitamin D= rickets, bone deformity, childbirth issues
Deficiency from agriculture (cereal based)= response to environmental and dietary changes
