Integumentary System and Body Temperature Study Guide

Mechanical and Chemical Barrier: The skin acts as a primary line of defense, serving as a mechanical and chemical barrier against the external environment.
Protection of Internal Structures: It provides a physical shield to safeguard underlying organs and tissues from damage.
Immune Response Participation: The system actively participates in the body's immune response by detecting and reacting to foreign pathogens.
Excretory Function: The skin performs an excretory role by releasing certain waste products from the body.
Vitamin D Synthesis: The skin acts as a gland to synthesize Vitamin D when exposed to sunlight.
Sensory Role: It houses various sensory receptors that allow the body to perceive touch, pressure, pain, and temperature.
Temperature Regulation: The system is vital in helping to regulate the body's internal temperature to maintain homeostasis.

Epidermis: The outermost layer of the skin. * Stratum Germinativum: This is the deeper layer of the epidermis where cell division occurs; it is essential for the continuous renewal of skin cells. * Stratum Corneum: The surface layer of the epidermis, consisting of dead, flattened, keratinized cells that provide a tough, protective covering. * Keratinization: The process by which cells move from the deeper stratum germinativum to the surface, filling with the tough protein keratin and eventually dying to form the stratum corneum.
Dermis: The layer located directly beneath the epidermis, containing blood vessels, nerves, and accessory structures.
Subcutaneous Layer (Hypodermis): Located beneath the dermis. * Insulation: This layer contains adipose tissue that insulates the body from temperature extremes. * Anchoring: It serves to anchor the skin to the underlying structures, such as muscles and bones.
Accessory Structures: Includes hair, nails, and various glands embedded within the skin layers.

Transdermal: Medications are applied to the skin surface for absorption through the skin into the bloodstream (e.g., patches).
Intradermal: Medications are injected into the dermis, just below the epidermis.
Topical: Medications are applied directly to the surface of the skin for local effects.
Subcutaneous: Medications are injected into the subcutaneous tissue layer beneath the dermis.

Melanin: A dark pigment produced by melanocytes located in the epidermis. * Melanocytes may malfunction, leading to conditions such as Albinism (lack of pigment), Vitiligo (loss of pigment in patches), or the formation of moles (concentrated pigment).
Carotene: A yellow pigment present in the skin. In most individuals, the presence of melanin obscures or overshadows the tint of carotene.
Physiological Changes: * Blushing: Results from the dilation of blood vessels (vasodilation) near the skin surface. * Pallor: Results from the constriction of blood vessels (vasoconstriction), causing a pale appearance.
Pathological Changes: * Cyanosis: A bluish tint to the skin indicating poor oxygenation of the blood. * Jaundice: A yellowing of the skin caused by the deposition of bilirubin. * Bronzing: Occurs due to the overproduction of melanin. * Ecchymosis: Visible black and blue bruising caused by blood leaking into the surrounding tissue.

Hair: Includes specific parts, and varies by color and texture. * Arrector Pili Muscles: Small muscles attached to hair follicles that cause the hair to stand up (goosebumps). * Hair Loss: The physiological or pathological shedding of hair.
Nails: Specialized structures that protect the ends of fingers and toes.
Glands: * Sebaceous Glands: Glands that secrete sebum (oil) to lubricate the skin and hair. * Sweat Glands: * Apocrine Glands: Usually associated with hair follicles in the axillary and genitocrural regions; respond to emotional stress. * Eccrine Glands: Widely distributed glands primarily responsible for thermoregulation through sweat production. * Modified Sweat Glands: * Mammary Glands: Specialized glands that produce milk. * Ceruminous Glands: Glands located in the ear canal that produce cerumen (earwax).

Normal Body Temperature: Set at approximately $98.6^{\circ}\,\text{F}$ .
Normal Range: Temperature typically fluctuates between $97^{\circ}\,\text{F}$ and $100^{\circ}\,\text{F}$ .
Core vs. Shell Temperature: Core temperature refers to the temperature of deep internal organs, while shell temperature refers to the temperature of the skin and surface tissues.
Thermoregulation: The process of regulating body temperature to stay within a healthy range. * Hypothermia: A dangerous drop in body temperature due to thermoregulatory failure. * Hyperthermia: A dangerous increase in body temperature due to thermoregulatory failure.
Heat Production: Primarily generated through metabolic processes (metabolism).

Radiation: Heat is lost from a warm object (the body) to the cooler air surrounding it.
Conduction: Heat is lost from the warm body directly to a cooler object that is in physical contact with it.
Convection: Heat is lost via cool air currents moving over the surface of the skin.
Evaporation: The process by which a liquid (sweat) becomes a gas in response to temperature, cooling the surface of the skin.

Types of Perspiration: * Sensible Perspiration: Visible sweating produced by sweat glands. * Insensible Perspiration: Water loss through the skin and lungs that occurs without being noticed.
Animal Chilling Mechanisms: * Squirrels use their waving tails to dissipate heat. * Elephants use their large ears to wave and cool down. * Dogs use panting as a primary method of heat loss. * Vultures excrete waste along their own legs to facilitate cooling.

Heat Loss: Neonates lose more heat than they can produce for several reasons: * They have a large surface area relative to their body mass. * They possess a very thin layer of subcutaneous fat for insulation. * They are physically unable to shiver to generate heat.
Heat Dissipation: Newborns also have a very limited capacity to dissipate excess heat if they become overheated.

Partial-Thickness Burns: * First-degree: Damage limited to the epidermis. * Second-degree: Damage involving both the epidermis and the dermis.
Full-Thickness Burns: * Third-degree: Extensive damage destroying the epidermis, dermis, and potentially reaching the subcutaneous layer and underlying structures.
Rule of Nines: A clinical tool used to estimate the percentage of total body surface area affected by burns.
Eschar: The dead, leathery, charred tissue that forms following a severe burn, which can often act as a breeding ground for bacteria and may require removal.