Skin

Question 1

What are the layers of the skin?

Answer 1

Epidermis
Dermis
Hypodermis

Question 2

What cells are found in the epidermis?

Answer 2

Keratinocytes
Merkle cells
Melanocytes
Langerhans cells
T cells

Question 3

What cells are found in the dermis?

Answer 3

Elastic & fibrous tissue of connective tissue
Nerve endings, Blood vessels, lymph vessels, piloerector muscle, hair follicles, sweat glands, sebaceous glands.

Question 4

What is found in the hypodermis?

Answer 4

Subcutaneous fat layer
Thermal insulator
Energy store

Question 5

What are the stages of wound healing?

Answer 5

Bleeding - Clot
Inflammatory - Scab, macrophage, Fibroblast
Proliferative - Fibroblast proliferating, and subcutaneous fat heals
Remodelling - Dermis and epidermis layer heals.

Question 6

What occurs during haemostasis?

Answer 6

• Injury of blood vessel
• Injured vessel contract
• Coag cascade activated by tissue factor
• Clot formation & platelet aggregation
• Cytokines activate fibroblast, macrophages & endothelial cells.
• Serotonin released which increases vascular permeability.

Question 7

What occurs during early inflammatory phase?

Answer 7

*Activation of the complement system
* Infiltration of neutrophils within 24-48hrs
* Diapedesis into wound & phagocytosis of bacteria & foreign particles.
* Dying cells cleared by macrophages / extrusion to wound surface.

Question 8

What occurs in the late inflammatory phase?

Answer 8

• Blood monocytes arrive & become macrophages (48-72hrs)
• Cytokines and GF to recruit fibroblast, keratinocytes & endothelial cells to repair dmg
• Collagenases to degrade tissue
• Lymphocytes enter wound (>72hrs) involved in remodelling.

Question 9

What occurs during the proliferative phase (72hrs - 2 weeks)?

Answer 9

• Fibroblast migration - Proliferate & construct new ECM
• Collagen synthesis - strength & integrity
• Angiogenesis - TGF-B, PDGF, capillary sprouts invade fibrin rich would clot and organise microvascular network
• Granulation tissue formation
• Epithelialisation - Single layer of epidermal cells migrate from wound edges form delicate covering & new basement membrane.

Question 10

What occurs during remodelling phase?

Answer 10

• Fibronectin & HA broken down
• Collagen bundles increase in diameter and strength
• Ongoing collagen synthesis & breakdown by TGF-B & MMP
• Capillary outgrowth halted & blood flow decrease
• Acellular, avascular scar results

Question 11

What local factors affect wound healing?

Answer 11

• Pressure
• Infection
• Necrosis
• Mechanical injury
• Infection
• Oedema
• Topical Agents
• Lack of CO2

Question 12

What is Atopic dermatitis?

Answer 12

Type 4 Hypersensitivity reaction
Occurs with asthma / hay fever
Commonly affects knees, elbows, wrists, neck & face

Question 13

What are the clinical features of atopic dermatitis?

Answer 13

Dry skin
Itching may be severe, especially at night
Red to brownish grey patches on affected area
Raw, sensitive, swollen skin from scratching.

Question 14

What is the treatment for atopic dermatitis?

Answer 14

Emollients
Topical CC
Antibiotics
Phototherapy
Systemic CC
Topical Calcineurin –| (Pimecrolimus, Tacrolimus)
Immunosuppressant - Ciclosporin, Azathioprine
Dupilimumab - MAB

Question 15

What is contact dermatitis?

Answer 15

Substances at home/workplace responsible for it
More common in adults than in children.

Question 16

What is allergic dermatitis?

Answer 16

Type 4 hypersensitivity reaction
Immune response builds up
Diagnosis - Patch testing

Question 17

What is the treatment of contact dermatitis?

Answer 17

Emollients
Topical CC
Oral CC