12. Skin and Breast Flashcards
What are the 7 main functions of the skin?
- Barrier to infection
- Waterproofing
- Thermoregulation
- Protect against trauma
- Protect against UV light
- Vitamin D synthesis
- Sensation
Describe the epidermis basement membrane.
- Not usually visible on H&E
- Made of type 4 collagen
What are the 5 layers of the epidermis?
- Basement membrane
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum corneum
Describe the stratum basale.
- Sits on the basement membrane
- Basal epithelial cells (stem cells)
- Contains melanocytes
What is the main function of melanocytes of the skin?
Synthesise melanin and transfer it to surrounding keratinocytes in melanosomes in response to MSH and ACTH stimulation
What is the main function of melanin?
Absorbs ultraviolet light, protecting us from non-ionising radiation damage
Describe the stratum corneum.
- Acellular
- Plates of keratin
- Prominent at certain sites
Describe the stratum spinosum.
- Plump polygonal keratinocytes
- Prominent intercellular adhesions
- Langerhans cells
- Merkel cells
What do Langerhans cells in skin do?
Antigen recognition
What is the purpose of Merkel cells?
Sensory
Describe the stratum granulosum.
- Flattened squames
- Eosinophilic cytoplasm
- Haematoxophilic kerato-hyaline granules
What are epidermal adnexae?
Downgrowths of the epidermis into the dermis
Name 4 epidermal adnexae.
- Hair follicles
- Sebaceous glands
- Eccrine sweat glands
- Apocrine sweat glands
What are sebaceous glands?
- Accompany hair follicles
- Produce sebaceous secretions which lubricate and waterproof hairs
- Holocrine secretion
What are apocrine glands?
- Accompany hair follicles
- Axillae and groins
- Ceruminous glands in the ear
- Simple coiled tubular glands
- Pheromones?
- Eosinophilic cytoplasm
- Apocrine secretion
What are eccrine glands?
- Thin watery secretion
- Everywhere
- Coiled tubes 2 cell layers thick (inner secretory, outer myoepithelial)
- Eccrine secretion
Describe dermo-epidermal junctions.
- Ridged
- Epidermis protrudes downwards into underlying dermis
- Space between these is the papillary dermis
What are the 3 layers of the dermis?
- Papillary dermis
- Reticular dermis
- Subcutis
What does the dermis contain? (8)
- Irregular loose connective tissue
- Fibroblasts
- Collagen
- Glycosaminoglycan matric
- Blood vessels and lymphatics
- Nerves
- Sensory cells
- Scattered inflammatory cells
Describe the Meissner’s corpuscle sensory structures of the dermis.
- Encapsulated unmyelinated nerve endings
- Fine touch
- Dermal papillae especially in hairless skin
Describe the Pascinian corpuscle sensory structures of the dermis.
- Large ecapsulated sensory receptors
- Vibration and tickle
- Deep dermis
- Central non-myelinated nerve and surrounding lamellae of modified Shwann cellls
- Fluid-filled space separates inner core of lamellae from an outer lamella
Describe the subcutis.
- Adipose tissues
- Fibrovascular septa
- Insulation
- Shock-absorber
- Food store
What is breast tissue?
- Tissue present from birth but develops at puberty
- Collection of modified sweat glands
- Myoepithelial system of ducts and lobules set in fibroadipose connective tissue
- Ducts empty into nipple
Describe the terminal duct lobular units of the breast.
- Lobules arranged around a terminal duct
- Set in loose fibrous connective tissue
The ducts and lobules of the breast are lined by what 2 layers of cells?
Outer myoepithelial and inner columnar epithelial
What happens in the breast at lactation?
Inner layer secretory cells become vacuolated
What are the 3 principal histological layers of the skin?
Epidermis, dermis and subcutis
