SKIN Flashcards
What are the 3 layers of skin?
Epidermis, Dermis, Subcutaneous fatty tissue
Layers of epidermis
Stratum corneum, lucidum, granulosum, spinosum, basale
COME LETS GET SUN BURNT
What does the stratum corneum contain ?
Annulated keratinocytes
What does stratum lucidum contain?
Annulated keratinocytes (with keratohyalin)
Stratum granulosum contains?
Keratohyaline granules
Lysosomal enzymes
Odland bodies (lipids, prevents water loss)
Stratum spinosum?
Has 5-10 layers
Plump polygonal keratinocytes
Langerhans and merkel cells
Stratum basal?
Basal epithelial cells and melanocytes
Columnar perpendicular to basement membrane
Mitotically active
Skin brick wall model - good picture on SUGER renal and skin power point for revision
In the model the skin cells are the bricks
Corneodesmosomes are steel rods that join cells together (the adhesion molecules that keep corneocytes together)
The lipid lamellae is the cement
pH of healthy skin?
5.5
Function of vitamin D in stratum corneum?
Produces anti microbial peptides for defending skin from bacteria and viruses
Profilaggrin
Found in stratum granulosum. Cleaved to filaggrin
What is the significance of an acidic pH
Maintains environment unsuitable for serine protease activity
Healthy skin barrier - look at PTS notes - what do they contain?
Swelled corneocytes, cornified envelope which surround corneocytes, intact corneodesmosomes between corneocytes and lipid lamellae
NMF iS found in swelled corneocytes
What is it
Natural moisturising factor - collection of natural humectants which maintain skin hydration - produced by filaggrin - also helps maintain acidic environment at outer surface of stratum corneum
How do we balance the introduction of new cells in the basal layer of the epidermis?
Mature corneocytes are shed from the surface of the swelled corneocytes(dunno what SC stands for) in process called desquamation
What is desquamation?
The degradation of extracellular corneodesmosomes by proteases regulated by protease inhibitors
Optimum ph for serine protease activity?
Slightly alkaline in contrast to normal acidic ph of the skin
Where is vitamin D synthesised?
Stratum spinosum
Pneumonic for layers of epidermis
Come let’s get sun burnt
What are Annulated keratinocytes?
Dead keratinocytes
They are keratinocytes attached to the basement membrane via hemidesmosomes
They migrate upwards towards the corneum where desquamation occurs
Where are corneocytes found ?
Stratum corneum
Corneocytes involved in?
Protection
Keratohyaline granules
Lysosomal enzymes
Odland bodies
All involved in?
Preventing water loss
What are keratinocytes, Langerhans and Merkel Cells involved in?
Immunity sensation
Melanocytes involved in?
Skin pigmentation - how dark you are
What are the 2 parts of the dermis?
Superficial - Papillary dermis
Deep - reticular dermis
Function of the dermis?
Gives skin strength and elasticity
Components of the dermis?
Papillary dermis: meshwork of type 3 collagen and elastic fibres
Reticular dermis: bundles of type 1 collagen - contains sebaceous glands sweat glands and sensory cells
What does the subcutaneous fatty layer contain
Hypodermis
Adipocytes with fibrous tissue
Functions: insulation energy store shock absorbent
What does the lipid lamellae do?
Keeps water inside the cell - irritants and allergens bounce off surface of skin due to lipid lamellae - acts like a barrier
The importance of profillagrin?
- Profilaggrin and therefore Filaggrin not present which Causes a Lack of NMF
- Less H2O retention in corneocytes
- pH goes up
- Damages corneodesmosomes, damage to skin barrier
- Breakdown of skin barrier
- Increased risk of infection
Skin flare ups
Caused by allergens which are unable to penetrate skin
Met by lymphocytes which release chemicals
The chemicals induce inflammation
Red skin is due to…
Dilation of blood vessels
Itchy skin due to…
Stimulation of nerves
Dry skin due to…
Skin cells leaking due to lymphocyte activity
