Integumentary system Flashcards
Integumentary system
the skin and its accessory structures form the body’s integumentary system. The skin is the body’s largest organ as it covers the entire outside of the body. The skin of the average adult covers 1.5 to 2.0 square meters and is about 2 to 3 mm thick. Tooth enamel is considered part of the integumentary system.
Function: Protection
skin and accessory structures guard the body from invasions by pathogens and other foreign substances. It also protects the body by minimizing body fluid loss, assisting in heat regulation, and excreting waste products
Function: Thermoregulation
integumentary system in combination with the respiratory system regulates and balances the body’s internal temperature at approximately 98.6 F for other systems to function properly.
(a) Mechanisms of heat loss – if the body becomes too warm, a message is sent from the hypothalamus to the brain. The dermal capillaries dilate (widen), and more blood flows to the skins surface. The increased surface blood facilitates body loss through radiation, convection, evaporation, or conduction.
(b) Mechanism of heat production and conservation – blood vessel constriction, shivering, and goose flesh are thermoregulation processes that help warm the body. When the body becomes too cool, dermal capillaries constrict, reducing the amount of heat lost through the skin. Reflex action of shivering helps produce added heat and goose flesh raises the hairs on the skin to provide insulation. The more subcutaneous fat a person has, the better the body’s ability to insulate heat.
Function: Metabolism
Provides insulation (skin, hairs, subcutaneous fat) NOTE: metabolism is used to make the skin, hair, and nails
(b) Helps produce and use vitamin D. Vitamin D is important for bone growth and repair. The vitamin is produced in the skin when stimulated by sunlight (ultraviolet light) via enzymes
(c) Helps the body eliminate certain waste products through sweating
(d) Contributes to changes in cardiac output and blood pressure
NOTE: Contains the blood vessels that constrict and dilate, affecting blood pressure and cardiac output.
(e) Absorbs gases; some oxygen, nitrogen
Function: Sensation
Perceives stimuli: heat, cold, pain, pressure, touch, vibration, injury. Stimuli from the outside world is received through the skin. Finger tips are more sensitive than other areas such as palms and soles of the feet
(b) Provides social and sexual communication
(c) Allows for physical intimacy. The skin detects comfortable sensations and also facilitates communication between a newborn and its parents via touch
Function: Communication
Communicates feelings and moods through facial expressions. Smiles are understood by all people and blushing usually changes skin to a redder or darker hue
(b) Portrays feelings of anger, embarrassment, or fear (e.g., flushing, sweating, and pallor)
(c) Portrays body image via skin and hair’s general appearance
Function: Storage
(a) Stores water
(b) Stores fat
(c) Stores vitamin D
Structures: Epidermis
outermost, protective layer of the skin. The outer most layer of the epidermis (stratum corneum) is relatively waterproof and provides a barrier against heat, light, bacteria, and other foreign substances. The layer is thicker in soles of the feet and thinnest in the eyelids. Keratin creates a waterproof barrier and is the body’s true protector which prevents most microorganisms from penetrating unbroken skin. The inner most layer of the epidermis is composed of living cells. The living inner epidermal cells continually replace outer cells toward the body’s surface.
Structures: Dermis
also known as the corium, which is known as the “true skin.” The dermis is the thickest skin layer and composed entirely of live cells. Blood and lymphatic vessels in the dermis nourishes the epidermis. The dermis contains blood and lymph vessels, nerve endings, glands, hair follicles, sweat and oil glands. Collagen is found in the dermis which is a connective tissue which is a tough, resistant, and flexible fibrous protein. In youth, collagen is loose and elastic and hardens and loses elasticity with age.
Structures: Subcutaneous tissue
Subcutaneous tissue – also known as hypodermis or fatty layer which lies beneath the dermis and above the layer of muscle. Subcutaneous tissue attaches the epidermal and dermal layers to underlying organs and help cushion, protect, and hold the structures in place. It also serves as a heat insulator with the formation of lipocytes (fat cells).
Structures: Hair
derives from the subcutaneous fatty layer and covers almost all of the skin except for a few areas such as the lips, palms, and soles of the feet. Male hormones (testosterone) are responsible for the greater density of hair. Hair is composed of keratinized cells which is grown from the hair follicle. The dead portion of the hair is above the skin known as the shaft. The part lying below the skin is known as the root. Hair grows approximately 1mm every 3 days. Arrector pili are smooth muscles which when contracted cause the hairs to stand erect creating goose bumps. Primary function of hair is protection from sunlight and insulation from cold. Eyelashes and eyebrows keep dust particles and perspiration out of the eyes. Nostril hairs protect against inhaling objects and foreign particles.
Structures: Nails
tightly packed cells of the horny layer of the epidermis and help protect the sensitive tips of fingers and toes. They also help a person grab and pick up objects. The nail is made up of keratinized dead cells. Nail growth occurs in the nail matrix and the new cells push the older cells away from the nail bed at about 1mm per week. A nail will continue to regrow as long as the live cells in the nail bed remain undamaged.
