4.2 Basic Skin Biology

Question 1

What is the function of the skin?

Answer 1

• Protective barrier
• Temperature regulation
• Sensation
• Vitamin D syntehsis
• Immunosurveillance
• Cosmesis- psychological wellbeing of skin

Question 2

What is erythroderma?

Answer 2

More than 90% of body surface area affected, erythematous and exfoliative

Question 3

What are the complications of erthyroderma?

Answer 3

Total skin failure
- Hypothermia- loss of thermoregulation
- Infection
- Renal failure- insensible losses
- High output cardiac failure (dilated skin vessels)
- Protein malnutrition (high skin turnover)

Question 4

What are the causes of erythroderma?

Answer 4

Psoriasis
Eczema
Drugs
Cutaneous T cell lymphoma

Question 5

What are the symptoms of erythroderma?

Answer 5

Pruritus
Fatigue
Anorexia
Feeling cold

Question 6

What are the signs of erythroderma?

Answer 6

Erythematous
Thickened
Inflamed
Scaly
No sparing- rash is all over

Question 7

What are the 3 layers of the skin?

Answer 7

Epidermis
Dermis
Hypodermis

Question 8

What are the 4 major cell types in the skin?

Answer 8

Keratinocytes
Langerhan cells
Melanocytes
Merkel cells

Question 9

What do keratinocytes do?

Answer 9

Form a protective barrier

Question 10

What do langerhans cells do?

Answer 10

Anitgen presenting cells

Question 11

What do melanocytes do?

Answer 11

Produce melanin

Pigment which absorbs light and protects cell nuclei from UV DNA damage

Question 12

What do merkel cells do?

Answer 12

Contain specialised nerve endings for sensation

Question 13

What are the layers of the epidermis?

Answer 13

Come lets get sun burnt

Stratum corneum
Startum lucidum
Stratum granuolsum
Stratum spinosum
Stratum basale

Each layer represents a differnt stage of maturation of the keratinocyte

Question 14

What is the average epidermal turnover time?

Answer 14

30 days

Question 15

Where do you find stratum lucidum?

Answer 15

Areas of thicker skin such as palms and soles

Question 16

What can pathology of the epidermis cause?

Answer 16

Change in:
- Epidermal turnover
- Surface of the skin
- Pigmentation of the skin

Question 17

How does psoriasis present?

Answer 17

Scaley-silver colour
Plaques
Erythematous
Well defined

Question 18

How does vitiligo present?

Answer 18

Well defined
Patches of hypo-pigmentation

Question 18

What is the dermis composed of?

Answer 18

Collagen
Elastin
Glycosaminoglycans

Question 19

What does the dermis do?

Answer 19

Provides strength and elasticity

Question 20

What does the dermis also contain?

Answer 20

Immune cells
Nerve scells
Skin appendages
Lymphatics
Blood vessels

Question 21

What is dermatographia?

Answer 21

Marks on skin stay for long periods of time, so you can write on the skin

Question 22

What is a wheal?

Answer 22

Discrete, transient raised mark caused by oedema in the dermal layer

Question 23

What do sebaceous glands do?

Answer 23

Produce sebum through hair follicles

Secretes sebum on to the skin for lubrication

Question 24

What causes the activation of sebaceous glands?

Answer 24

Puberty Stimulation by conversion of androgens to dihydrotestosterone

Question 25

What is associated with acne vulgaris?

Answer 25

Increased sebum production and bacterial colonisation

Question 26

What are the two types of sweat glands?

Answer 26

**Eccrine** - Widespread over body **Apocrine** - Active after puberty - Found in axillae, areolae, genitalia and anus

Question 27

What do sweat glands do?

Answer 27

Regulate body temperature Innervated by sympathetic nervous system

Question 28

What does a hair consist of?

Answer 28

Modified keratin Divided into: Hair shaft Hair bulb

Question 29

What are the 3 main types of hair?

Answer 29

**Lanugo**- covers foetus **Vellum**- short hair all over **Terminal**- coarse long hair

Question 30

What are the stages of hair follicle growth?

Answer 30

Anagen Catagen Telogen Disrupted in cancer

Question 31

What are the two types of hair loss?

Answer 31

**Patchy**- Alopecia areata **Male pattern baldness**- androgen-driven

Question 32

What are the different parts of a nail?

Answer 32

Nail plate Arises from the nail matrix at the posterior nail fold Nail plate rests on nail bed

Question 33

What part of the nail contains capillaries?

Answer 33

Nail bed

Question 34

What conditions can affect nails?

Answer 34

**Eczema and psoriasis** Thickening and separation of the nail from the bed **Melanoma** Hyperpigmented linear lesion on nail