The Skin - Topical Drug Delivery W3

Question 1

What is the skin

Answer 1

• Largest organ in the body
• Weighs 2.5kg
• Complex, highly immune capable organ
• Protects us against contaminated atmosphere
• Performs protective, sensory and homeostatic functions

Question 2

The skin serves to ….

Answer 2

• Protect the internal body structures by merging with respiratory, genitourinary and digestive tracts
• Limit entry into the body of noxious chemicals, allergens etc
• Stabilise body temperature, BP
• Act as sensory organ (heat, cold, touch, pain)

Question 3

When skin comes in contact with noxious agent

Answer 3

◦ Some may pass across the top layer (stratum
corneum)
◦ Some may be metabolised in the lower layers
(viable epidermis)
◦ Sensing of and reaction to chemical damage in
epidermis and dermis
◦ Removal of chemical by bloodflow through
vessels in the dermis

Question 4

What are keratinocytes

Answer 4

Keratinocytes represent the major cell type of the epidermis, the outermost of the layers of the skin, making up about 90 percent of the cells there.

They originate in the deepest layer of the epidermis, the stratum basale and move up to the final barrier layer of the skin, the stratum corneum.

Question 5

What is keratinocyte differentiation

Answer 5

Differentiation of keratinocytes is critical for epidermal stratification and formation of a protective stratum corneum.

It involves a series of complex processes leading through gradual changes in characteristics and functions of keratinocytes up to their programmed cell death via cornification.

Keratinocytes at the basal layer of the epidermis are proliferative, and as the cells mature up the epidermis, they slowly lose proliferative potential and undergo programmed destruction.

Question 6

What is the epidermis

Answer 6

the top layer of skin in your body

Question 7

What is the stratum corneum

Answer 7

the outermost layer of the epidermis and marks the final stage of keratinocyte maturation and development.

• non viable epidermis
• 200-800 mions thick on palmar and plantar
• keratin rich dead cell layer and metabolically inactive

Question 8

What are Melanocytes

Answer 8

highly differentiated cells that produces a pigment melanin inside melanosomes which is taken up by keratinocytes

Question 9

What is the dermis

Answer 9

• Middle skin layer, 1-5mm fibrous and elastictissue
• Supportive and cushioning tissue composed mainly of collagen (70%), elastin and fibrillin
• Sparse cellular population
  ◦ Nerve endings
  ◦ Blood vessels
  ◦ Lymph vessels
  ◦ Hair follicles
  ◦ Sweat glands
  ◦ Sebaceous glands

Question 10

What are skin appendages

Answer 10

Entry points

1. eccrine sweat glands
   - simple, coiled, tubular glands present throughout the body, most numerously on the soles of the feet
2. apocrine sweat glands
   - Most apocrine glands in the skin are in the armpits, the groin, and the area around the nipples of the breast and have odour
3. hair follicles
4. nails