Untitled Flashcards Set

### **1. Epithelium Layers (Skin)** The **epidermis** (top layer of skin) is made up of **stratified squamous epithelial tissue**. This tissue is composed of multiple layers of flat cells arranged upon a basal membrane. The epidermis is avascular, meaning it contains no blood vessels. Nutrients and waste products diffuse to and from cells in the dermis below. It has **5 layers** (from bottom to top): 1. **Stratum basale** - Bottom layer, also known as the stratum germinativum - Where **new skin cells** (keratinocytes) are made through cell division (mitosis) - Contains **melanocytes** (produce melanin, the pigment responsible for skin color), Merkel cells (sensory touch receptors), and keratinocyte stem cells 2. **Stratum spinosum** - Several cell layers thick - Cells start making **keratin** (a strong, fibrous protein that protects the skin) - Cells are alive and connected by desmosomes (cell junctions that provide strength and flexibility) - Langerhans cells (immune cells) are abundant in this layer 3. **Stratum granulosum** - Thin layer where cells begin to **flatten and die** - Filled with more **keratin** and lamellar granules (contain lipids that create a water barrier) - Cells undergo apoptosis (programmed cell death) in this layer 4. **Stratum lucidum** *(only in thick skin: palms and soles)* - Thin, clear layer found only in thick skin - Composed of dead keratinocytes - Provides extra protection and reduces friction in areas subject to wear and tear 5. **Stratum corneum** - Outermost layer of the epidermis - Made of **dead, flat cells** (corneocytes) full of keratin - Continuously shed and replaced by new cells from below - Provides a protective barrier against water loss, abrasion, and microbial invasion - Protects against water and bacteria

### 💉 **2. Dermis Components** The **dermis** is the **layer beneath the epidermis** and is made of **connective tissue**. It is thicker than the epidermis and provides support, strength, and elasticity to the skin. The dermis is highly vascularized and innervated, containing blood vessels, nerves, and sensory receptors. It has **two layers**: #### 🔹 Papillary Layer (Top part) - Superficial layer of the dermis, adjacent to the epidermis - Made of **loose connective tissue** (primarily collagen and elastin fibers in a ground substance) - Contains: - **Capillaries** (tiny blood vessels that supply nutrients and remove waste) - **Sensory receptors** (Meissner's corpuscles for light touch and free nerve endings for pain and temperature) - **Dermal papillae** (finger-like projections that extend into the epidermis, forming fingerprints and increasing surface area for nutrient exchange) #### 🔹 Reticular Layer (Deeper part) - Deeper, thicker layer of the dermis - Made of **dense irregular connective tissue** (primarily thick bundles of collagen fibers) - Provides strength, elasticity, and structural support to the skin - Contains: - **Sweat glands** (eccrine and apocrine glands that produce sweat for thermoregulation and excretion) - **Sebaceous (oil) glands** (produce sebum, an oily substance that lubricates and protects the skin and hair) - **Hair follicles** (structures that surround the hair root and produce hair) - **Blood vessels** (larger blood vessels that supply the dermis and epidermis) - **Nerves** (sensory nerves that transmit touch, pressure, pain, and temperature sensations) - **Collagen and elastic fibers** (give strength and stretch to the skin)

### 🔥 **3. Rule of 9’s – Burn Assessment** The **Rule of 9's** is a quick way doctors estimate **how much of the body is burned** in adults. It assigns percentage values to different body regions, making it easier to calculate the total body surface area (TBSA) affected by the burn. It helps decide **how serious the burn is** and **how much fluid** the patient might need for resuscitation. Each major area of the body is assigned a **percentage**: | Body Region | Percentage of TBSA | | :----------- | :------------------- | | Head and Neck | 9% | | Each Upper Limb | 9% | | Front of Trunk | 18% | | Back of Trunk | 18% | | Each Lower Limb| 18% | | Perineum | 1% | | | | | | |