Skin Flashcards
Describe the basic function of the skin and the differences between the layers
- Epidermis - avascular epidermis, It undergoes proliferation and synthesises keritin
- Dermis - Vascular and tough, contains blood and lymphatic vessels and cutaneous nerves. It also contains collagen and elastin which are not replaced with age
- Hypodermis - varies with thickness, has blood/lymphatic vessels and nerves. Made of adipose tissue, has skin ligaments.
What are the layers of the epidermis?
S.Basale S.Spinosum S.Granulosum S.Lucidum S.Corneum Stratified, squamous, keratinised, epithelium.
Describe the function of the S.Basale?
It is the site of cell division and interface with the dermis
Name and describe a genetic condition that is associated with skin
Dystophic epidermolysis bullosa - mutation in the collagen 7 gene which causes blistering
Describe the function of S.Spinosum
The site of intermidate filaments (K1/K10) expression. The cells are joined by desmosomes
Describe the function of S.Granulosum
Contains keratohyaline granules and organisted keratin filaments
function of S.lucidum?
Involved in specialised cell death
Function of S.corneum
Contains waterproof ghost cells.
What aids cornification?
Filaggrin in keratohyaline granules
Cornification -process of epithelial cells turning into protective structures
What is filaggrin?
filament-associated protein that binds to keratin fibers in epithelial cells
Describe some of the features of Filaggrin
Maintains optimal skin barrier along with its precursor profilaggrin, it is the main compounent of keratohyline granules in the S.Granulosum, it aids keratin filament aggregation and inhibits water loss
Mutations in filaggrin cause what?
Keratinization disorders (icthyosis vulgaris -eczema)
Describe the function of melanocytes and where they are found
Found - basal layer
Function - release melanin
What is the function of melanin?
Absorb UV-B and prevents damage to cells in hypodermis. More melanin - less skin cancer
Tumour of melanocytes?
Melanoma
What are melanosomes?
Organelle responsible for the synthesis and storage of melanin. These are transfered to keratinocytes
What are Langerhans cells and describe their function?
Antigen processing and presenting cells.
Derived from monocytes, found mostly in the S.Spinosum.
The cells are activated in skin but migrate to lymph nodes.
They express langerin which help degrade viral particals in endosomes called birbeck granules.
Describe the three layers of the dermis
Dermo-epidermal junction - complex to avoid shearing (breaking). Papillae flatten with age making skin more vulnerable
Papillary Dermis - Made of fine collagen, elastic fibres and small blood vessels and nerves
Reticular dermis - coarser collagen and elastic fibres. Larger blood vessels and nerves
Describe the structure of the Hypodermis
Loose connective tissue and adipose tissue that varies in thickness. Supports hair follicles and sweat glands.
Superficial blood and lymphatic vessels
Cutaneous nerves
Skin ligaments determine mobility of skin implicated in scarring and incision
Responsible for vitamin D production
Describe the eccrine sweat glands
Secrete a water fluid
Lie in dermis and superficial fascia
Duct opens into surface of skin
Controlled in thermorgulation and is controlled by the SNS
Describe the Apocrine sweat glands
Found in the axilla and groin.
Open into hair follicles and releases a milky sectretion that contains pheromones.
List the components and functions of a pilosebaceous unit
pilosebaceous:
- Sebaceous Gland (Secretes sebum to lubricate hair and skin)
-Hair Shaft (Composed of keratin and grows from the bulb)
Arrector Pili (Contracts smooth muscle attached to papillary dermis)
What sensations does skin respond too?
Pain Temp Touch Pressure Vibration
What is the periodontal membrane?
Fibrous joint between teeth and skull
