Skin Functions & Disorders

functions of the skin

Protection:

• epidermis acts as a waterproof protective barrier

• helps keep microorganisms such as bacteria and fungi out

• melanocytes help protect against UV radiation from sunlight

Vitamin D Production

sunlight → skin cells produce inactive vitamin D → liver + kidneys activate it → vitamin D helps normal bone and tooth development

• inactive form is cholecalciferol

• activated form is calcitriol

Temperature Regulation:

Normal body temperature: 37°C = 98.6°F

• The body tries to balance: heat produced = heat lost

  • hyperthermia = temperature above 101°F

  • hypothermia = temperature below 95°F

how does the body regulate it’s temperature

TOO HOT = SWEAT + DILATE

1. Eccrine glands release sweat

2. Sweat evaporates

3. Evaporation cools the skin

4. Blood vessels dilate = get wider

5. More blood reaches the skin

6. Heat is released
   
   
   

TOO COLD = NO SWEAT + CONSTRICT + SHIVER

1. Eccrine glands become inactive

2. No sweat → conserve heat

3. Blood vessels constrict = become narrower

4. Less blood flows to the skin

5. Less heat is lost

6. Skeletal muscles contract slightly → shivering

7. Shivering produces more heat

what is the process to healing wounds

SHALLOW:

Epithelial cells near the wound divide faster → new cells fill the gap

DEEP

1. Blood escapes

• skin is injured

• nlood escapes from the blood vessels in the dermis

2. Blood clot forms

• the escaped blood forms a blood clot

• the clot + dried tissue eventually form a scab

• the scab protects the damaged area

3. Repair begins

• blood vessels send out new branches

• fibroblasts move into the area

• fibroblasts produce collagen fibers

4. Protection + healing

• the scab protects the damaged region while the skin repairs

• eventually, the damaged tissue is replaced and the scab comes off

what is inflammation

the tissues' response to injury or stress such as pain, warmth, redness, and swelling

Symptom	Why?

Redness

Blood vessels dilate → more blood enters the area

Heat	More blood + increased metabolic activity

Swelling

Blood vessels become more permeable → fluid enters tissues

Pain	Injury to neurons + pressure from swelling

what causes burns & how are they classified

Causes: thermal energy, electrical energy, chemical energy, electromagnetic energy

Classification: how deeply and severely they penetrate the skin

types of burns

1st Degree — Epidermis

• red, painful, dry, no blisters

2nd Degree — Epidermis + part of Dermis

• red, blistered, swollen, painful

• can appear wet and shiny, white or discolored

3rd Degree — Through all skin layers

• may look dry/leathery

• no pain because nerve endings are damaged

• coloring can be black, white, brown, yellow, and/or red

4th Degree — Beyond the skin

• muscle/bone may be exposed

• no pain because nerve endings are damaged

• coloring can be black, white, brown, yellow, and/or red

rule of nines & Parkland formula

Rule of Nines

a tool used to assess the total body surface area involved in burns

• Head & neck = 9%

• Chest = 9%

• Abdomen = 9%

• Upper back = 9%

• Lower back = 9%

• Entire right arm = 9%

  • Front = 4.5%

  • Back = 4.5%

• Entire left arm = 9%

  • Front = 4.5%

  • Back = 4.5%

• Entire right leg = 18%

  • Front = 9%

  • Back = 9%

• Entire left leg = 18%

  • Front = 9%

  • Back = 9%

Parkland Formula

equation used to estimate fluid resuscitation required for burn victims during the first 24 hours

• 4 mL × % BSA burned × body weight (kg)

  • total BSA must be greater than 20%

  • divide the answer by 2 to see how much fluid is needed during the first 8 and remaining 16 hours