Skin Flashcards
Go over skin histology
What is the major cell type in the skin? [1]
keratinocyte: produce keratin
What are the 4 main layers of the skin [4]
Four main layers
* Stratum basale (basal layer)
* Stratum spinosum (spinous layer)
* Stratum granulosum (granular layer)
* Stratum corneum (cornified layer)
Keratin is the most abundant protein in which skin layer? [1]
stratum corneum
State the function of the basal layer of the skin [2]
Single layer of cells
Stem cell proliferation occurs here:
Allows self-renewal and undergoes terminal differentiation
The basement membrane is made of which 3 structures? [3]
Which structures connect the keratin cytoskeleton to the basement membrane? [1]
Consists of Laminin 332, Collagen IV, and Collagen VII
Hemidesmosomes (integrin receptors) link keratin cytoskeleton to basement membrane
Describe characteristics of stratum spinosum [2]
5-8 cell layers thick
Numerous desmosomes give cells spiny appearance
Describe the strucure of stratum granulosum [3]
2-3 cell layers
Characterised by large keratohyalin granules:
* Filaggrin
* Involucrin
* Loricrin
Nucleus starts to breakdown
Describe the strucure of stratum corneum [4]
Main protective barrier of skin
Have a thick cornified envelope
Cross-linked by enzymes
Cells in cornified layer are dead (15-20 cell layers)
Intercellular lipids (ceramides) maintain moisture
Stratum corneum
Label A
Corneodesmosome
Label the different arrows [4]
Yellow: basal layer
Green: stratum spinosum
Blue: Granular layer
Red: Stratum corneum
Where is the only place tight junctions are found in the skin? [1]
top of stratum granulosum
What are the two layers of the dermis? [2]
What are the functions of the dermis? [3]
Papillary
Reticular
Provides strength and elasticity to skin; vascularised and innervated
What type of collagen is found in the papillary layer [1] and reticular layer [1] of the dermis?
Papillary: Type 3
Reticular: Type 1
Label the blue and yellow arrows [2]
Blue: papillary layer
Yellow: reticular layer
What are the two types of hair in the body? [2]
What is innervation like? [1]
Two types
Vellus - body hair
Terminal - scalp and secondary sexual hair
All have innervation
Matrix keratinocytes produce hair
Dermal papilla fibroblasts control hair growth
Where are the stem cells found in the hair follicle? [1]
Bulge region
How does hair follicle differentation occur?
COME BACK
Inner root sheath – 3 layers
Hair shaft – 3 layers
Hair-specific keratins
What are the 3 main phases of the hair cycle? [3]
3 main phases:
Anagen-active
Catagen-regressive
Telogen-resting
Describe the role of sebaceous glands [2]
Exocrine gland: cell ruptures and sebum released into sebaceous duct and onto skin
What are the two main components of eccrine sweat glands? [2]
Main role? [1]
Excretory duct
Secretory coil
Thermoregulation
Apocrine Gland found in which locations? [2]
What are apocrine glands associated with? [1]
Axilla and pubic region
Sweat gland associated with hair follicles
Specialised tissue-resident macrophage in skin are called? [1]
Langerhan cells: provide first line of defence.
Present antigen to T lymphocytes
Merkel cells are found in which layer? [1]
Function? [1]
Stratum basale
Sensory perception
Mast cells are found whhere in the skin? [1]
Function? [2]
Dermis
Immune response: secretes histamine
What are the 3 stages of normal wound healing of the skin? [3]
Phases
Inflammation
Proliferation
Maturation
Describe the inflammation stage of skin wound healin
Hemostasis
Fibrin clot
Leakage of neutrophils
Activation of resident immune cells
Active immune cell recruitment
* Blood vessel dilation
* Neutrophils then macrophages
* Mediated by ILs and TNFα etc
Describe the inflammation stage of skin wound healing [4]
Hemostasis
Fibrin clot
Leakage of neutrophils
Activation of resident immune cells
Active immune cell recruitment
* Blood vessel dilation
* Neutrophils then macrophages
* Mediated by ILs and TNFα etc
Describe the proliferation stage of skin wound healing [4]
Fibroblasts:
* Granulation tissue (type III collagen)
* Myofibroblasts
Angiogenesis
* Endothelial cells
Keratinocytes
* Re-epithelialization
* Altered adhesions and cell shape
Describe the maturation process of skin wound healing [3]
Collagen re-modelling (type 3 –> type 1 collagen)
Removal of cells
* Myofibroblasts, immune cells, redundant blood vessels
Appendages do not normally re-generate (i.e. hair follicles)
