Skin

Question 1

How large and weight is the skin

Answer 1

3.6kg

2m2

Question 2

What are the three layers of the skin

Answer 2

Epidermis

Dermis

Subcutis

Question 3

How is the skin a waterproof barrier

Answer 3

Tight junctions between cells in the stratum granulosum, epidermal lipids and keratin in stratum corneum form both an inside-out and outside-in barrier to water

Prevents trans epidermal wall loss

Question 4

Describe the role of the epidermis

Answer 4

Waterproofing
Physical barrier
Immune function
Vitamin D synthesis (endocrine)
UV protection
Thermoregulation

Question 5

Describe the role of the dermis

Answer 5

Thermoregulation
Vitamin D synthesis (endocrine)
Sensory organ

Question 6

Describe the role of the subcutis

Answer 6

Thermoregulation
Energy reserve
Vitamin D storage
Endocrine organ
Shock absorber

Question 7

What converts 7-dehyrocholestrol into previtamin D3 by UVB

Answer 7

Plasma membranes of epidermal keratinocytes and dermal fibroblasts

Question 8

When do serum vitamin D peak

Answer 8

24-48 hours after exposure

Question 9

What type of solubility is vitamin D

Answer 9

Lipid soluble - can be stored in subcutis adipocytes

Question 10

How is skin the site of hormone action

Answer 10

Androgens act on follicles and sebaceous glands

Thyroid hormones act on keratinocytes, follicles, dermal fibroblast, sebaceous glands, eccrine glands

Question 11

What does skin colour depend on

Answer 11

Melanin

Carotenoids

Oxy/deoxyhaemoglobin

Question 12

Describe melanin

Answer 12

Synthesised in melanosomes within melanocytes from tyrosine

Transported via dendrites to adjacent keratinocytes

Pheomelanin - red/yellow
Eumelanin - brown/black

Question 13

What do all skin types contain more of

Answer 13

Eumelanin than pheomelanin

Question 14

How does the skin act as an immune organ

Answer 14

Innate and acquired immune functions

Epidermis
- langerhans cells

Dermis
- regulatory T cells
- natural killer cells
- dendritic cells
- macrophages
- mast cells

Question 15

What layer is only present in thick skin

Answer 15

Stratum lucidum

Question 16

How would you know where skin is located

Answer 16

If it has no apocrine sweat gland it will not be located in the axilla and genital region

Question 17

What are the layers of the skin

Answer 17

Epidermis (outermost first)
- stratum corneum (keratinised tissue) - dead
- stratum lucidum (thick skin only) - dead
- stratum granulosa (thin layer) - alive (being to produce precursor)
- stratum spinosum
- stratum basal (germinating layer - mitosis)

Dermis
- capillary layer
- reticular layer

Hypodermis
- subcutaneous (adipose) tissue

Question 18

Where are melanocytes found

Answer 18

Stratum basal (bottom layer of the epidermis)

Question 19

What is the epithelium of the epidermis

Answer 19

Stratified squamous epithelium

Question 20

What is acne

Answer 20

Pilosebaceous unit - hair follicle and associated sebaceous gland

Increased sebum production from these glands leads to the development of comedones, papules and pustules on the skin

Question 21

What substances allows the skin to remain hydrated and keep slightly acidic

Answer 21

Natural moisturising factor

Question 22

What are the 3 signs a patient would present with if the skin was penetrated by allergens

Answer 22

Redness

Itchiness

Dryness

Question 23

What causes redness

Answer 23

Dilation of vessels

Question 24

What causes dryness

Answer 24

Skin cells damaged therefore leak water

Question 25

What causes itchiness

Answer 25

Stimulation of proprioceptors by the release of histamine

Question 26

Why does acne occur

Answer 26

Hair follicle becomes blocked with sebum/skin cells/bacteria

Question 27

What are the three types of junctions with adhere skin cells together

Answer 27

Adherens junctions

Desmosomes/coreneodesmosomes

Tight junctions