Skin Anatomy & Physiology

Question 1

What are the 3 layers of skin?

Answer 1

1. Epidermis/Stratum Corneum
2. Dermis
3. Hypodermis (fat)

Question 2

What is the Stratum corneum made of?

Answer 2

Dead cells, 15-20% of water content

Question 3

Describe the 5 main functions of the Stratum Corneum

Answer 3

1. Protection
   “Brick and mortar” system: prevents water loss, enables only very small controlled molecules to pass through [avoid dehydration, maintain body temp]
2. Antimicrobial
   SC is acidified -> increases antimicrobial defense
3. Antioxidant
   Vit E,C and glutathione are present to maintain normal conditions of the skin
4. Mechanical support
   Skin is elastic, will bounce back when there is physical trauma
5. UV barrier

Question 4

What is our skin’s pH?

Answer 4

between 5.4-5.9

but sebaceous secretions, age etc. affects the skin pH

Question 5

Name the differences between deodorants and antiperspirants

Answer 5

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)

Question 6

Describe the relation between skin & antimicrobial defense

Answer 6

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

Question 7

What are present in the stratum corneum to maintain normal conditions of the skin (homeostasis)?

Answer 7

Vit E (y-tocopherol), Vit C (ascorbic acid), glutathione

Question 8

What are the 3 scenarios of skin disorders?

Answer 8

1. Skin Disorders with a correlation to microbiota
2. Skin disorder without correlation to microbiota
3. Skin commensal that can become invasive to cause infection

Question 9

Describe skin diseases with a corr with microbiota (Seborrhoeic Dermatitis)

Answer 9

Chronic, relapsing, usually mild dermatitis
e.g. dandruff

Treatment: effective with antifungal drugs, not with antibacterial ones

Question 10

Describe skin diseases w/o corr to microbiota

Answer 10

Chronic wounds

e.g. diabetic ulcer

Question 11

Describe skin diseases caused by commensal microorganism (“accidental” pathogen)

Answer 11

S. epidermidis is a common skin commensal

Most frequent cause of hospital-acquired infection on medical devices such as catheters or heart valves

Question 12

What are the 3 main strategies/entry sites for delivering cosmetics to the skin?

Answer 12

1. Transcellular route
2. Transappendageal route
3. Stratum corneum intercellular lipid lamella

Question 13

What is transcellular route?

Answer 13

Through cells in the skin

to remain in the cells, a substance must be water soluble

Question 14

What is transappendageal route?

Answer 14

Through hair follicle glands
minimal contribution, reps only 0.1% of whole skin
highest hair follicle density is in the forehead and calf regions

Question 15

How does the stratum corneum intercellular lipid lamella work?

Answer 15

Through pore spaces

Question 16

What are chemical enhancers for?

Answer 16

To temporarily permeage skin so that chemicals can pass through skin
e.g. sulphoxides, azone, fatty acids, essential oils