INTRODUCTION TO SKIN Part 1- Epidermis
INTRODUCTION TO SKIN Part 1- Epidermis
SKIN ANATOMY
Image source: suggestkeyword.com
EPIDERMIS
Stratum Corneum
Stratum Granulosum
Stratum Spinosum
Stratum Basale
Stratum Lucidum
Image source: suggestkeyword.com
THE RELATION BETWEEN THESE 5 LAYERS
Stratum CorneumStratum GranulosumStratum SpinosumStratum Basale
Stage 1
Stage 2Stage 3
Stage 4
1 2 3 4
Image source: amazonnaws.com, usmagazine.com, country1067.com, pixnet.net
STRATUM BASALE
• Made up of keratinocyte stem cell.
• Undergoes mitosis division to constantly renew epidermal cells.
• Half of the cells differentiate and move to the next layer (stratum spinosum) to begin the maturation process- Keratinisation/ desquamation
• Other cell in stratum basale: Melanocyte Keratinocyte
SKIN DESQUAMATION
• is a natural process where skin cells are sloughed away and replaced.
• It takes approx. 28 days.
• The duration of keratinisation process will vary with different lifestyle, sun exposure, ageing and etc.
• Dead skin cells accumulation will result in pigmentation, dull skin, dehydration and etc. - Exfoliating can help in normalise skin regeneration.
MELANOCYTE• is a melanin producing cells.
• melanin is a pigment found in eyes, skin, and hair.
• Function is to protect skin cells and tissues from harmful UV radiation- transform the UV energy to heat.
• Almost everyone has the same amount of melanocyte,while the size and amount of melanosomes can be different.
• Most of the whitening products act on the process of melanogenesis.
Image source: palaeo.gly.bris.ac.uk
STRATUM SPINOSUM
• Retaining moisture and protect against foreign bodies and substances.
• Begin to synthesise keratin, which can hold water and retain moisture.
• Langerhans cells to detect skin penetration by foreign matter and transport the invaders to the lymph node.
• The malfunction/activation of langerhans cells can lead to sensitive skin.
Desmosomes
STRATUM GRANULOSUM
• Contain granules, which to bind keratin filaments together.
• Lamellar bodies are formed in the keratinocytes of stratum granulosum.
• When it matures to the stratum corneum, enzyme degrade the outer layer of lamellar bodies, releasing lipids such as ceramides, essential fatty acids and cholesterol.
• The lipids fuse with stratum corneum to form a continuous layer of lipids- called lamellar lipid bilayer- which is lipid soluble.
• impermeable to water soluble substances.
Image source: wisegeek.com
STRATUM CORNEUM
• Outermost layer of epidermis, consist of 15-20 layers dead cells.
• Corneocyte/Keratinocyte- protein complex that made of keratin. These keratin can hold large amounts of water between fibre. Contain NMF.
• Natural moisturizing factor (NMF)- water soluble compound that absorb water from the atmosphere to stay hydrate. Yet, they are easily leached from the cells with water contact.
• Intercellular lipid- consist of ceramide, free fatty acids and cholesterol. It can maintain the water balance by trapping water molecule
• Corneodesmosome- Diversify desmosome that hold the corneocyte together
Brick and mortar structure
STRATUM CORNEUM
• Water content in stratum corneum should remain approx 15-20%.
• The main functions of stratum corneum are
• to provide hydration to skin and prevent loss of water through the water holding/absorb properties and lipid bilayer.
• to protect skin against foreign bodies through the brick and mortar structure.
• The incomplete of stratum corneum can lead to several skin problems- such as dehyrated skin, aging skin, sensitive skin, oily skin and etc.
Brick and mortar structure
SEBUM• A combination of sebum that secrete by
the sebaceous gland and sweat.
• It’s slightly acidic (pH 4.5-6.5)
• Function:
• to inhibit the growth of bacteria due to the acidic environment
• Prevent water loss from the epidermis due to it’s waterproof nature
• Sebum is odorless, but it breakdown by bacteria can product strong odor
• The incomplete of sebum can lead to acne skin.Keratinocyte
Intercellular matrix
Sebum
Brick and mortar structureImage source: pinterest.com
CONTENT OF STRATUM CORNEUM
Sebum Corneocyte/Keratinocyte Intercellular Matrix
41% Triglyceride21% Wax estersAmino acids Lactic acid Cholesterol 12% Squalane Uric acid
80% Keratin protein20% amino acidsUric acidNMFPyrrolidone Carboxylic Acid
55% CeramidesCholesterolFree fatty acids
Keratinocyte
Intercellular matrix
Sebum
Brick and mortar structure
REVISION
Stratum basale • Skin regeneration• Secrete melanin
Stratum spinosum • Provide nutrients• Detect allegens
Stratum granulosum • Provide structural protection• to create skin barrier
Stratum corneum • Provide hydration• 1st layer to protect skin from
foreign bodies.
Stratum lucidum • Reduces effect of friction• Provides protection
Image source: rci.rutgers.edu
REFERENCE
• https://www.youtube.com/watch?v=OKosGSm7Ps4
• http://dermatology.about.com/
• http://www.taiwanlaser.com/
• http://www.wisegeek.com/
• https://www.wikipedia.org