Skin Anatomy & Physiology Flashcards
What are the 3 layers of skin?
- Epidermis/Stratum Corneum
- Dermis
- Hypodermis (fat)
What is the Stratum corneum made of?
Dead cells, 15-20% of water content
Describe the 5 main functions of the Stratum Corneum
- Protection
“Brick and mortar” system: prevents water loss, enables only very small controlled molecules to pass through [avoid dehydration, maintain body temp] - Antimicrobial
SC is acidified -> increases antimicrobial defense - Antioxidant
Vit E,C and glutathione are present to maintain normal conditions of the skin - Mechanical support
Skin is elastic, will bounce back when there is physical trauma - UV barrier
What is our skin’s pH?
between 5.4-5.9
but sebaceous secretions, age etc. affects the skin pH
Name the differences between deodorants and antiperspirants
Deodorants:
- decreases pH -> decreases auxillary bacteria
ingredients: antimicrobials with a positive charge or not
e. g. benzethonium chloride [+ charge], chlorhexidine, triclosan [no charge]
e. g. natural cmpds like eugenol, thymol, ethyl alcohol
Antiperspirants:
- blocks sweating by blocking temporarily the sweat glands
ingredients: metal salts like Aluminium, Zirconium chlorohydrate
sometimes botulinum toxin (botox)
Describe the relation between skin & antimicrobial defense
Salty secretions from sweat glands create an environment that is hyperosmotic & thus unfavourable for bacteria
A more acidic pH helps protect skin against colonisation by pathogenic bacteria
What are present in the stratum corneum to maintain normal conditions of the skin (homeostasis)?
Vit E (y-tocopherol), Vit C (ascorbic acid), glutathione
What are the 3 scenarios of skin disorders?
- Skin Disorders with a correlation to microbiota
- Skin disorder without correlation to microbiota
- Skin commensal that can become invasive to cause infection
Describe skin diseases with a corr with microbiota (Seborrhoeic Dermatitis)
Chronic, relapsing, usually mild dermatitis
e.g. dandruff
Treatment: effective with antifungal drugs, not with antibacterial ones
Describe skin diseases w/o corr to microbiota
Chronic wounds
e.g. diabetic ulcer
Describe skin diseases caused by commensal microorganism (“accidental” pathogen)
S. epidermidis is a common skin commensal
Most frequent cause of hospital-acquired infection on medical devices such as catheters or heart valves
What are the 3 main strategies/entry sites for delivering cosmetics to the skin?
- Transcellular route
- Transappendageal route
- Stratum corneum intercellular lipid lamella
What is transcellular route?
Through cells in the skin
to remain in the cells, a substance must be water soluble
What is transappendageal route?
Through hair follicle glands
minimal contribution, reps only 0.1% of whole skin
highest hair follicle density is in the forehead and calf regions
How does the stratum corneum intercellular lipid lamella work?
Through pore spaces
What are chemical enhancers for?
To temporarily permeage skin so that chemicals can pass through skin
e.g. sulphoxides, azone, fatty acids, essential oils
