Ultrastructure of Skin Flashcards
(23 cards)
What is glabrous skin?
Thick skin over palms and soles
Free from hair
What are the three layers of skin, from superficial to deep?
Epidermis
Dermis
Hypodermis
What cell type largely forms the epidermis?
Keratinocytes undergoing terminal maturation
What is cornification?
Process of keratinocytes undergoing terminal maturation
- Increased keratin production
- Migration towards external surface
What non-keratinocyte cells are found in the epidermis?
Melanocytes
Langerhans cells
Merkel cells
What are melanocytes?
Produce melanin - gives skin pigment
What are Langerhans cells?
Antigen-presenting dendritic cells
What are Merkel cells?
Sensory mechanoreceptors
What are the strata of keratinocytes of the epidermis, from deepest to superficial, and what is occurring in each strata?
Stratum basale = mitosis of keratinocytes
Stratum spinosum = keratinocytes joined by tight intercellular junctions = desmosomes
Stratum granulosum = cells secrete lipids and other waterproofing molecules
Stratum lucidum = cells lose nuclei and drastically increase keratin production
Stratum corneum = cells lose all organelles, continue to produce keratin
How long does a keratinocyte take to travel from the stratum basale to the stratum corneum?
30-40 days
What connects the dermis to the epidermis?
Dermo-epidermal junction
What are the two layers of the dermis, from superficial to deep?
Papillary layer
Reticular layer
What is the role of the reticular layer of the dermis?
Provide durability, given its thicker bundles of collagen
What cell types and structures are found in the dermis?
Fibroblasts Mast cells Blood vessels Cutaneous sensory nerves Skin appendages
What is the function of fibroblasts in the dermis?
Synthesise extracellular matrix
What are the predominant components of the extracellular matrix of the dermis?
Collagen
Elastin
What are the skin appendages contained within the dermis?
Hair follicles
Nails
Sebaceous and sweat glands
What is a pilosebaceous unit?
Hair follicle + sebaceous glands
With which muscle is the hair follicle associated and what is its function?
Arrector pili - contracts to cause follicle to stand upright
What are the two types of sweat glands?
Eccrine
Apocrine
What are eccrine sweat glands?
Major type Release clear, odourless substance comprised mostly of - NaCl - Water - Involved in thermoregulation
What are apocrine sweat glands?
Larger
Located in axillary and genital regions
Products of these glands broken down by cutaneous microbes, producing body odour
What comprises the hypodermis?
Subcutaneous tissue
