Physiology

Question 1

What UV light is most damaging to skin?

Answer 1

UVB

UVA

Question 2

What does skin metabolise

Answer 2

Vit D
Thyroid hormone (80% in skin, 20% in thyroid)

Question 3

What allows for thermoregulation of skin

Answer 3

Thermoreceptors

Eccrine glands

Question 4

Name the 3 types of wound healing

Answer 4

Primary Intention
- edges approximated (brought together) by stitches

Secondary Intention (too large for stiches/ stiches would cause serious distortion of surrounding tissue)

Question 5

Explain the stages of secondary intention

Answer 5

1. Inflammation
   - platelets form inital clot
   - leucocytes phagocyse bacteria in wound bed
   - keratinocyte proliferation takes over
2. Proliferation and tissue remodelling
   - Granulation tissue is stimulated
   - Fibroblasts lay down matrix and contract the wound (fibroplasia)
   - Endothelial cells develop blood vessels (angiogenesis)
3. Tissue remodelling
   - Fibroblasts lay down collagen
   - Scar is formed over several months

Question 6

Describe the difference between different degrees/thickness of burns

Answer 6

First degree - epidermis only
Second degree/ partial thickness - epi and dermis
Third degree/ full thickness - beyond dermis

Question 7

What may be expressed on the surface of chronic wounds that must be removed to allow for proper healing?

After how many weeks does a wound become chronic?

Answer 7

Slough - mix of dead cells, polymorphs and bacteria

> 6 weeks

Question 8

What 4 things lead to the cause of pressure sores (bed sores, pressure ulcers, decubitus ulcers)

Answer 8

Prolonged pressure over bony area
Lack of blood flow
Friction from bedding/clothing
Irritation from sweat/blood/urine/faeces

-> breakdown of skin -> erosion and ulceration

Question 9

Why is primary intention healing quicker than secondary intention healing?

Answer 9

In primary edges are approximated so less of a defect to heal

Question 10

How might you ensure good healing of a laceration to the hand?

Answer 10

Clean
Suture
Consider antibiotics

Question 11

What factors must be considered in a patient with a chronic wound?

Answer 11

• Other co-morbities e.g. diabetes, arthritis, anaemia
• Infection
• Circulation
• Nutrition

Question 12

How can pressure sores be prevented?

Answer 12

Regularly turning patient
Use special matresses 
Keep skin clean and hydrated 
Regular skin assessment 
Good nutrition

Question 13

What is cutaneous photosensitivity?

What are the two types?

Answer 13

Phototoxicity - almost all get it

Photoallergy - only hypersensitsed

Question 14

Explain the scale of Fitzpatrick sunreactive sun phototypes:

SPT I to IV

Answer 14

I - can’t tan always burn

IV - never burns

Question 15

Only get radiation damaged if absorbed by …

Answer 15

Chromophores

Question 16

Look more at this

Sign of cutaneous photosensitivity

Answer 16

Retroauricular

Question 17

Poryphyrias

Answer 17

Where they accumulate are dependant on water and lipid soluble

Question 18

What are the 4 main groups of porphyrias?

Answer 18

Phototoxic - v little visible signs
Blistering adn fragility
Acute attack (some with no skin involvement)
Severe congential porphyrias (very rare)

Question 19

Phototoxic

Answer 19

Intense burning pain lasts 3-6 days after onset

helps to apply a cold compress

Question 20

Phototoxic

Answer 20

Intense burning pain lasts 3-6 days after onset

helps to apply a cold compress

Question 21

Unilocular vs multilocular

Answer 21

Unilocular - lone

Multilocular - Having or consisting of many small compartments or cavities

Question 22

Name 4 non-immunological host defences in the skin

Answer 22

Physical barrier
- keratin layer

Physiological factors
- low pH

Sebaceous glands

• lysozymes
• ammonia
• hydrophilic oils

Commensal organisms
- fight for scarce resources

Question 23

Why is UV light carcinogenic?

Answer 23

Damages keratinocytes DNA -> mutates tumour supressor genes