Skin Structure and Function Flashcards
Name the layers of the skin
Epidermis (outermost)
Dermo-epidermal junction
Dermis
Sub-cutis
Appendages (hair, glands, nails)
What is the pilosebaceous unit?
Sebaceous gland draining into the side of a hair follicle
What are the layers of the epidermis, from the skin surface down?
Keratin layer
Granular layer
Prickle cell layer
Basal layer
Describe the production and loss of keratinocytes in the epidermis
Produced by stem cells in the basal layer
Migrate to prickle cell layer –> granular layer –> keratin layer –> shed
How long does the keratinocyte cycle of production and loss take in normal skin?
About 28 days
Which condition is associated with increased rate of keratinocyte production and loss?
Psoriasis –> cycle takes about 4 days
Name three other cell types found in the epidermis
Melanocytes
Merkel cells
Langerhans cells
What do melanocytes do?
Produce melanin to protect the skin from UV radiation
Which condition is caused by patches of absent melanocytes?
Vitiligo
What are Merkel cells?
Fine touch receptors
What are Langerhans cells?
Skin immune cells
How are keratinocytes held together in the epidermis?
By desmosomes in the prickle cell layer
Which condition results from IgG antibodies against desmosomes?
Bullous pemphigus
Where are the antibodies attacking in bullous pemphigoid?
Dermo-epidermal junction
What are the two main types of connective tissue in the dermis?
Collagen
Elastin
Name some cells that are present in the dermis?
Fibroblasts
Mast cells
Langerhans cells
Macrophages + lymphocytes
What do fibroblasts do?
Produce collagen and elastin
What results from over proliferation of fibroblasts?
Dermatofibroma (benign)
What do mast cells release and what type of rash does it cause?
Histamine
Urticaria
Which condition is a disorder of the pilosebaceous unit?
Acne
Which protein is important for the skin’s barrier function and which condition is it deficient in?
Filaggrin
–> deficiency in eczema
What does hyperkeratosis mean?
Increased thickness of the keratin layer
What does parakeratosis mean?
Persistence of nuclei in the keratin layer (normally no nuclei)
What does acanthosis mean?
Increased thickening of the epidermis
What does spongiosis mean?
Oedema between keratinocytes
