Structure and Function of the Skin Flashcards
What are the three layers of the skin
epidermis
Dermis
Hypodermis
Epidermis
avascular epithelium, undergoes proliferation and synthesises keratin
Dermis
vascular and tough contains: -blood vessels -lymphatics -cutaneous nerves -collagen -elastic fibres
Hypodermis
Superficial fascia - varies in thickness
contains:
-blood vessels, nerves, lymphatics
-fatty tissue
-skin ligaments, loose skin, taut skin implication in scarring and incisions
What elements are present in thick skin LGBCS
s. cornuem - water proof
s. lucidum - apoptosis
s. granulosum - keratin
s. spinosum - desmosomes
s. basale - cell division
What is the role of hemidesmosomes
anchor basal cells to basal lamina
how is the dermis held to the basal lamina
collagen 7
What mutation to the collagen VII causes blistering
dystrophic epidermolysis bullosa
Whats the role of filaggrin in keratohyline granules
aids cornification
role of melanocytes
found in the basal layer of the epidermis and they synthesis and release brown pigment known as melanin
What is the role of melanin
absorbs UV-B and prevents damage to DNA in the underlying cells of the hypodermis
melanoma is caused by exposure to radiation
Where are melanocytes derived from
neural crest cells these synthesise specialised lysosomes to undergo exocytosis of melanosomes which are transferred to keratinocytes
Langerhans
derived from macrophages dendritic form stratum spinosum capture, process and present antigens active in skin migrate to lymph nodes
What do langerhans express which helps degrade viruses
langerin = birbeck granules in HIV
what makes up the papillary dermis
fine collagen and elastic fibres, small blood vessels and nerves
what makes up the reticular dermis
coarser collagen and elastic fibres and larger blood vessels and nerves
what does the hypodermis support
deepest part of hair follicles
eccrine and apocrine glands
RESPONSIBLE FOR VIT D PRODUCTION
Where are apocrine sweat glands found
axillae and genital region, milk secretion containing pheromones
Hair follicles
cylindrical, epithelial structures anchored in the hypodermis grows from bulb composed of keratin contain sabaceous glands secrete sebum
What makes up the pilosebaceous unit
hair follicle
sebaceous glands
hair shaft
arrector pili
nails and teeth
nails: nail root growth passes deep in dermis
teeth: enamel develops from epithelium dentine pulp and periodontal membrane is mesodermal
What are arrecctor pili
contraction of smooth muscle attached to the papillary dermis and to the sheath of the follicle pulls the hair upright controlled by SNS
