Skin Structure Flashcards
What type of epithelium is skin?
Stratified sqaumous
Name the 4 layers of the epidermis from superficial to deep?
Strateum corneum
Granular
Prickle cell
Basal cell
How thick is the epidermis + what cell accounts for 95% + what do they differentiate into?
1.5 mm
Keratinocyte
Corneocytes
How many days does it take for a keratinocyte to migrate from the basal layer to the strateum corneum?
28
What is special about corneocytes + explain?
No nuclei
Lost at granular cell layer
What organelle is found in the strateum corneum and granular layer + function + role in each layer?
Lamellar/ Odland bodies
Secrete lipids
SC = form waterproof seal
GCL = trap water to provide moisture
Where is the keratin layer at its thickest?
Palms and soles of feet
What shape of keratinocytes are found in the granular layer + type of granule and contents?
Flat cells
Keratohyalin granules
Fillagrin and involucrin
What shape of keratinocytes are found in the prickle cell layer + key layer feature + resident APC?
Polyhedral
Desmosomes
Langerhans
Most metabolically active layer responsible for epidermal proliferation?
Basal cell
Shape of basal cell layer keratinocytes + arrangement?
Cuboidal
Single layer
Name 4 other features of the basal cell layer?
Hemidesmosomes
Laminin
Collagen IV
Free nerve endings
How is the epidermis vascularised?
By the vessels within the papillary dermis
What type of tissue is the DEJ + 2 layers?
Connective tissue
Lamina lucida
Lamina densa
What anchors the basal cell layer to the DEJ?
Hemidesmosomes
What is the function of ground substance + what does it contain/not contain?
Fill the space between fibres and cells
All the components of the extracellular matrix EXCEPT from fibres
Name the 3 main components + 3 main cells of the DEJ?
Ground substance
Collagen
Elastin
Fibroblasts
Mast cells
Macrophages
Explain how wrinkles form.
Damage to collagen/elastin forms long fibres. Further damage forms short fibres (wrinkles)
What 2 types of collagens are found in the dermis + what are they made by?
Type I
Type III
Fibroblasts
What are anchoring fibrils made of + attachments?
Type VII collagen
DEJ to type III collagen in dermis
Name the 2 layers of the dermis from superficial to deep?
Papillary
Reticular
Function of the papillary vs reticular dermis?
Projects into the epidermis
Contains more fibre for support
Which layer of skin contains the free nerve ending + most nerves and vessels?
Basal cell layer
Dermis
What specialised nerve is found in the papillary dermis + what does it feel?
Meissener’s corpuscle
Light touch and vibration
What specialised nerve is found in the reticular dermis + what does is feel + shape?
Pacinian corpuscle
Deep pressure
Onion
Blood supply is less than metabolic needs of the dermis. True or False?
False - blood supply greater than metabolic needs
Where are melanocytes mainly found + explain the production, transfer and function of melanin.
Basal cell layer
Melanosomes convert tyrosine to melanin
Dendrites transfer melanin onto nucleus of adjacent
Acts as protection against UV radiation
Name the 2 types of melanin + colour.
Eumelanin = brown/black/blue Phaeomelanin = red/pink/yellow
Where do Langerhans cell originate + 3 places found + type of cell + key organelle?
Bone marrow
Prickle cell layer, dermis, lymph nodes
APC
Birbeck/ racket granule
What layer and position are Merkel cells found + type of cell + what causes cancer of these cells?
Basal cell layer between a keratinocyte + nerve
Mechanoreceptors
Viral infection
Explain the stem of the pilosebaceous unit in the dermis.
Papilla stemming from matrix with blood vessels
Name the layers of a hair from internal to external.
Medulla
Cortex
Internal root sheath
External root sheath
Name 2 associated structures of the pilosebaceous unit + function.
Arrector pili muscle = movement
Sebaceous gland = lubrication
Name the 3 types and meanings of hair growth phase (ACT) + meaning + which phase is 90% of hairs in?
Anagen = growing = 90% of hairs Catagen = involuting Telogen = resting
Name the 3 types of hair (LVT) + where they are found.
Lanugo = foetus
Vellus (fine hair over body)
Terminal (coarse hair on scalp, axilla etc.)
Name the main component of hair and nails.
Keratin
How fast to fingernails grow each day + are toenails slower or faster?
0.1 mm
Slower
Name the 3 regions of nail.
Matrix
Nail root
Nail Plate
Name for the white semi-circle part of the nail, cuticle and area where free edge meets skin.
Lanula
Eponychium
Hyponychium
Where does the epidermis, dermis and melanocytes originate from in embryology?
Epidermis = ectoderm cells forming single layer periderm Dermis = mesoderm Melanocytes = neural crest
Name the layers of the skin at 4 weeks.
Periderm
Basal layer
Dermis
By what week have all the skin layers formed and melanocytes migrated + week when appendages form?
Week 16
Week 26
What are Blaschko’s lines?
Direction of skin growth that does not follow vessels or nerves
Name the 3 types of skin gland and secretion + which is the most common?
Eccrine = sweat = most common Sebaceous = lubricant Apocrine = odorous fluid
Difference in eccrine and sebaceous gland control?
Eccrine = sympathetic Sebaceous = hormonal
Where are sebaceous glands found + 3 functions?
Next to pilosebaceous unit
Lubricates hair follicle
Moisture loss
Prevents fungal infection
When do apocrine glands develop + what do they produce + only 3 places found?
Puberty
Scent
Axilla, genitals, nipples
