Skin physiology Flashcards
what are the 3 layers of skin from superficial to deep
epidermis
dermis
subcutis
list features of skin that make it waterproof and why is it important
Tight cell junctions between cells in stratum granulosum
Epidermal lipids
Keratin in stratum corneum
prevents transepidermal waterloss
which layer of skin is important for protecting against UV
Epidermis
which layer of skin is waterproof
epidermis
what is the endocrine function of the skin
vitamin D synthesis
why does skin wrinkle when wet
vasoconstriction in dermis
improves grip
why is the subcutis skin layer a shock absorber
contains fat
list some functions of the skin
Barrier to infection
Thermoregulation
Protection against trauma
Protection against UV
Vitamin D synthesis
Regulation of H2O loss
what converts 7-dehydrocholesterol in plasma membranes of epidermal keratinocytes and dermal fibroblasts to prevtamin D3
UVB rays
7-dehydrocholesterol in ______ ______ of epidermal keratinocytes and _______ _______ converts to previtamin D3 by UVB
plasma membranes
Dermal fibroblasts
Vitamin D is _____ soluble
a)water
b)fat
fat
T/f the skin is an endocrine organ
T
which hormones Is produced in the skin
D3
what are the 3 determinants of skin colour
Melanin
Carotenoids
Oxy/deoxyhaemoglobin
what cells are melanin produced in
melanosomes In melanocytes from tyrosine
does more melanin = more or less able to utilise UV light to make Vitamin D
less
How is skin a barrier to infection
A range of peptides synthesised by granular layer keratinocytes:
Cathelicidin-related antimicrobial peptide (Cramp – called LL37 in humans)
β defensins
S100A7 and S100A8
how is skin an immune organ
Epidermis = langerhans cells
Dermis= Regulatory T cells, Natural killer cells, dendritic cells, macrophages, mast cells
what do langerhans cells secrete
cytokines
how does skin regulate body temperature
Subcutaneus fat for insulation
Eccrine sweating, cutaneous blood flow = heat loss
what are the 2 types of melanin
Pheomelanin (red/yellow)
Eumelanin (brown/black)
