Introduction To Skin Flashcards
Skin functions
Barrier
Insulation
Provides Sensory info
Vitamin D synthesis
What molecule in cell membranes is vitamin D synepthesised from
7-dehydrocholesterol
2 major layers of skin
Epidermis
Dermis
4 main layers of epidermis + extra layer on palms and soles
Stratum basal
Startum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Major cell types in epidermis
Keratinocyte
Epidermis epithelium type
Stratified squamous
What type of filament does keratin form
Intermediate filament
How does pH of type 1 and type 2 keratin differ
Type 1 acidic
Type 2 basic
How do keratin molecules pair up
Specific pairs
Always acidic Type 1 with basic type 2 to ensure overal protein neutral
What cells in the epidermis proliferate
Adult stem cells in Basal layer
What do basal cells of the epidermis adhere to
Basement membrane
Components of basement membrane
Laminin 332
Collagen IV
collagen VII
Hemidesmosomes
Integrin receptors on keratinocyte cytoskeleton which link to basement membrane
What structure anchors the epidermis to the dermis
Basement membrane
What gives the stratum spinosum a histological spiny appearance
Desmosomes
Desmosome
Structures holding cells together at Adhesive intracellular junction
Number of Cell layers in stratum spinosum, granulosum and corneum,
S - 5-8
G 2-3
C 15-20 dead
Cells in Which layer of the epidermis contain keratohyalin granules
Stratum granulosum
Proteins contained in keratohyalin granules
Filaggrin
Involucrin
Loricrin
Why do stratum granulosum cells appear granular
Large keratohyalin granules
In what layer of the epidermis do nuclei start to break down
Stratum granulosum
What type of molecule and ceramides
Intracellular lipids
What layer of the epidermis has flat dead cells and a thick cornified envelope
Stratum corneum
What structure connects cells in the stratum corneum
Corneodesmosomes
Histological characteristics of each layer of the epidermis
Corneum - non nuclei or organelles
Granulosum - grainy
Spinosum - larger rounder cells w paler nuclei
Basal - small compact cells w dark nuclei
Junction types
Tight junction
Adheren junction
Gap junction
Desmosomes
2 layers of the dermis
Papillary - more superficial
Reticular - deeper
Main tissue type in dermis
CT
Most abundant cell in dermis
Fibroblasts
What cell synthesises collagen elastin and proteoglycans in the dermis
Fibroblast
Components of papillary layer of dermis
Many capillaries
Randomly orientated type III collagen
Elastin
Collagen type on papillary and reticular layer of dermis
Papillary type III
Reticular type I
2 types of hair follicle
Vellus - body hair
Terminal - scalp and secondary sexual
Which cells make up hair in hair follicles
Matrix keratocytes
Which hair follicle cells control hair growth and how do they do this
Dermal papilla fibroblasts
Signal to hair follicle cells to proliferate
Which part of the hair follicle contains HF stem cells and what protein do they express
Bulge region
Keratin 15
Number of layers in the hair shaft and number of layers in the root sheath
3 in each
3 phases of hair growth cycle
Anagen - active
Catagen- regressive
Telogen - resting
Are sebaceous glands exocrine of endocrine
Exo
Why do sebaceous glands enlarge at puberty
Androgen sensitive
How is sebum released onto skin
Sebum contained in mature sebocytes in sebaceous glands -> sebocytes rupture -> sebum released into sebaceous duct and onto skin
Infection of which glands causes acne
Sebaceous glands
2 man in components of eccrine sweat glands
Excretory duct
Secretory coil
Apocrine glands
Sweat gland associated with hair follicle
Where are apocrine sweat glands found
Axilla
Pubic region
When do apocrine sweat glands become active
Puberty
2 types of sweat glands
Eccrine
Apocrine
Melanocyte
Dendritic cell found in the epidermis which produce melanin
Where are melanocytes found
In epidermis on basement membrane and hair matrix
What is the function of melanosomes
Store melanin in melanocytes
Injected into keratinocytes
2 types of melanin
Eumelanin - brown/black
Pheomelanin - red
How does melanin protect against UV
Absorbs UV
Langerhans cell
Specialised tissue resident macrophage found in basal and spinous layers
Langerhans cell function
Take up, process, and present antigens
Merkel cell location and purpose
Stratum basale
Sensory perception
Mast cell location and function
Dermis
Immune response and histamine secretion
3 wound types and layers they effect
Superficial - epidermis
Partial thickness - epidermis + dermis
Full thickness - epidermis + dermis + hypodermis
3 phases of wound healing
Inflammation
Proliferation
Maturation
Parts of inflammation phase of wound healing
Hemostasis - fibrin clot
Neutrophil leakage
Resident immune cell activation
Active immune cell recruitment
What part of the inflammation stage of wound healing is mediated by ILs and TNFalpha
Immune cell recruitment
Do macrophages or neutrophils respond first
Neutrophils
Parts of proliferation stage of wound healing
Granulation tissue formation from fibroblasts
Angiogenesis
Myofibroblasts contract to contract wound
Re epithelialisation by keratinocytes
Parts of Maturation stage of wound healing
Collagen remodelling - 3->1
Removal of myofibroblasts, immune cells, and redundant blood vessels
Complications of wound healing
Infection
Chronic wounds
Scarring
What causes a keloid scar
Fibroblasts produce collagen beyond what is needed
Difference between androgenetic alopecia and alopecia areata
Androgenetic - male pattern
Areata - auto immune