Structure And Function Of Skin

Question 1

What are is the epidermis

Answer 1

Outer layer of skin (3 cell types, majority of cells are keratinocytes)

Question 2

What’s contained in the dermis (4)

Answer 2

Collagen and elastin matrix with mucopolysaccharide gel, fibroblasts, dermal dendritis cells, macrophages

Question 3

Explain the maturation of skin cells in the epidermis

Answer 3

5 layers of epidermis
Cells mature from the stratum basale up to the stratum corneum (outer layer)
They lose their nucleus as they differentiate and become protein envelopes that then fall off (whole process ~1month, conditions such as psoriasis = few days)

Question 4

Functions of skin (6)

Answer 4

Thermoregulation (insulation, heat transfer)
Skin immune system (innate and adaptive functions)
Barrier (protects against: mechanical, chemical, microorganisms, UV)(keeps in: water and electrolytes, macromolecules)
Sensation (temperature, touch, pain)
Vitamin D synthesis
Interpersonal communication (physical appearance, smell, self-identity - skin diseases can affect confidence)

Question 5

What are the external (5) and internal (4) causes of skin disease

Answer 5

External: temperature, UV, chemical, infection, trauma
Internal: systemic disease, genetics, drugs, infection

Question 6

How do autoimmune conditions cause skin disease

Answer 6

Immune system attacks the joints between the epidermis and dermis

Question 7

What is a macule

Answer 7

Small (less than 5mm) flat circumscribed area (non-palpable change in skin colour with distinct borders)

FRECKLES

Question 8

What is a patch

Answer 8

Large flat circumscribed area (non-palpable change in skin colour with distinct borders)

Question 9

What is a papule

Answer 9

Palpable solid lesion less than 1cm in diameter

Question 10

What is a plaque

Answer 10

Palpable, solid lesion greater than 1cm in diameter

Question 11

What is a nodule

Answer 11

Palpable, lesion more than 1cm in diameter which is taller than it is wide

Question 12

What is a vesicle

Answer 12

Fluid-containing, superficial, thin-walled cavity less than 1cm

Question 13

What is a bulla

Answer 13

Fluid-containing, superficial, thin-walled cavity greater than 1cm

Question 14

What is an erosion

Answer 14

Skin defect where there has been loss of the epidermis only

Question 15

What is an ulcer

Answer 15

Skin defect where there has been loss of the epidermis and dermis

Question 16

What is a pustule

Answer 16

Pus containing, superficial, thin-walled cavity

Question 17

What is an abscess

Answer 17

Thick-walled cavity containing pus

Question 18

What investigation should be done if bacterial skin infection suspected

Answer 18

MC&S (microscopy, culture, sensitivities)
Charcoal swab

Rub cotton bud on infection (if pustule can pop then swab)

Question 19

What investigation should be done if viral skin infection suspected

Answer 19

Viral swab for PCR (can pop the vesicle and sample fluid)
If systemic illness take throat swab

Question 20

What investigation should be done if fungal skin infection suspected

Answer 20

Skin scraping
Nail clipping
Hair sample

Fungal cultures