1. Skin Injury and Repair

2. Skin Injury and Repair Four Stages in Skin Healing Inflammation
Blood flow increases
Phagocytes attracted
Scab formation
Cell division and migration
Scar formation

3. Skin Injury and Repair
Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response.
Epidermis
Dermis
After several hours, a scab has formed and cells of the stratum germinativum are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving with the enhanced circulation
in the area. Clotting around the edges
of the affected area partially isolates
the region.
Sweat
gland
Scab
Macrophages
and
fibroblasts
Migratory
epithelial
cells
Granulation
tissue

4. Skin Injury and Repair
One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating.
Fibroblasts
After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis.
Scar
tissue

5. Skin Injury and Repair
Table 5-1

6. Aging of the Skin Major Age-Related Changes
Injury and infection increase
Immune cells decrease
Sun protection diminishes
Skin becomes dry, scaly
Hair thins, grays
Sagging, wrinkles occur
Heat loss decreases
Repair slows

7. Effects of UV Radiation
Beneficial effect - activates synthesis of vitamin D3
Harmful effects
Sun burn
Wrinkles, premature aging
Malignant melanoma
Basal cell carcinoma

8. Types and Growth of Hair
Vellus hairs
Body hairs of women and children
Terminal hairs
Hair of scalp
Axillary and pubic area (at puberty)
Hair thinning and baldness
Due to aging
Male pattern baldness

9. Burns Classified by severity
First-degree burn – only upper epidermis is damaged
Second-degree burn – upper part of dermis is also damaged
Blisters appear
Skin heals with little scarring
Third-degree burn
Consume thickness of skin
Burned area appears white, red, or blackened

10. Rule of Nines Assesses the percentage of burn Used to guide treatment
Determines transfer to a burn unit
Different for Adult and children

11. Estimating Burns Using the Rule of Nines
Figure 5.11a

12. Skin Cancer Basal cell carcinoma Squamous cell carcinoma Melanoma
Least malignant and most common
Squamous cell carcinoma
Arises from keratinocytes of stratum spinosum
Melanoma
A cancer of melanocytes
The most dangerous type of skin cancer

13. Skin Cancer Squamous cell carcinoma Basal cell carcinoma Melanoma
Figure 5.12