Integumentary

I went through your slides on skin anatomy, burns, and wound types

# Integumentary System, Burns & Wounds Overview

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## 1. Layers of the Skin & Structure

### Epidermis

- Tissue type: Stratified squamous epithelial tissue.

- Layers (from deep to superficial):

1. Stratum basale: Constantly dividing cells pushing up toward the surface.

2. Stratum spinosum: "Spiny layer" several cells thick; contains pre-keratin filaments.

3. Stratum granulosum: Cells begin to flatten and disintegrate; accumulates keratin granules for waterproofing.

4. Stratum lucidum: Clear translucent layer found only in thick skin (palms and soles).

5. Stratum corneum: Top layer made of 20–30 layers of dead, keratinized cells that regularly shed.

Melanocytes

Spider-shaped cells in the stratum basale and spinosum that produce melanin to protect skin cells from UV radiation. Everyone has a similar number of melanocytes; skin tone depends on the amount of melanin produced.

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### Dermis & Hypodermis

- Dermis composition: Dense irregular connective tissue containing blood vessels, nerves, sweat glands, and hair follicles.

- Papillary layer: Loose connective tissue forming wavy dermal papillae (creates fingerprints/epidermal ridges).

- Reticular layer: Bundles of collagen fibers arranged along lines of cleavage (tension). Surgical cuts parallel to these lines heal faster with minimal scarring.

- Temperature regulation: Blood vessels dilate (swell) during exercise/heat to dissipate heat, turning the skin red. Prolonged pressure restricting blood flow causes decubitus ulcers (bedsores).

- Hypodermis (Subcutaneous layer): Not technically part of the skin; composed of loose fatty connective tissue that anchors skin to muscle/bone and insulates the body.

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## 2. Skin Appendages

| Appendage | Key Features | Functions / Characteristics |

| :--- | :--- | :--- |

| Eccrine Sweat Glands | Merocrine glands opening directly onto skin pores. | Sweat is 99% water, acidic, and contains dermcidin (antimicrobial peptide). Found on palms, soles, forehead. |

| Apocrine Sweat Glands | Found in axillary (armpit) and genital areas. | Secretes sweat + proteins and fats; odorless until broken down by bacteria (causes body odor); activates at puberty. |

| Sebaceous Glands | Holocrine glands attached to hair follicles (none on palms/soles). | Secretes oily sebum to lubricate skin/hair and kill bacteria. |

| Hair | Made of hard keratin; grows from the hair bulb inside the follicle (located in dermis). | Arrector pili muscle makes hair stand up. Hair shaft is covered by an outer cuticle. |

| Nails | Made of hard keratin; grown by the nail matrix. | Eponychium (cuticle) seals the matrix; lunula is the white half-moon area at the base. |

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## 3. Burn Classifications & Calculations

### Degrees of Burns

- 1st Degree (Superficial): Affects only epidermis. Red, painful, dry, no blisters (e.g., mild sunburn).

- 2nd Degree: Affects epidermis and part of dermis. Red, swollen, blistered, wet/shiny, painful.

- 3rd Degree: Destroys epidermis, dermis, and subcutaneous layer. White, brown, yellow, black, or leathery; no pain because nerve endings are destroyed. Large areas need skin grafting.

- 4th Degree: Extends into muscle and bone; blackened/charred, no pain, often requires amputation.

Parkland Formula

Used for fluid resuscitation within the first 24 hours for burns involving \(>20\%\) Total Body Surface Area (TBSA, counting 2nd and 3rd degree burns only):

\[ \text{Total Fluid (mL)} = 4\text{ mL} \times \text{Weight (kg)} \times \%\text{TBSA} \]

- First 8 hours: Administer \(\frac{1}{2}\) of the total calculated volume.

- Next 16 hours: Administer the remaining \(\frac{1}{2}\) of the volume.

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## 4. Types of Wounds

- Laceration: Jagged tear caused by blunt force; scars more than straight incisions; needs pressure and bandaging.

- Incision: Clean surgical cut with smooth edges; healed with soap/water cleaning and bandaging.

- Abrasion ("Road rash"): Surface skin rubbed off by friction; cleaned with soap, water, and debris removal using tweezers.

- Puncture: Deeper than it is wide; risk of surface healing too fast and trapping bacteria/infection inside.

- Avulsion: Skin torn completely away from underlying tissue; requires surgical reattachment or skin grafting.

Would you like to try practice questions on the Parkland formula or do a quick quiz to test this?

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