Integumentary system Flashcards
Protection
The skin covers the body and acts as a physical barrier that protects underlying tissues from physical damage, ultraviolet rays, and pathogenic invasion. By keeping fluids inside the body, the skin also protects against dehydration.
Body temperature maintenance
The skin contains sweat glands that secrete (produce and release) fluid in the form of perspiration. This process helps regulate the body’s internal temperature.
perception of stimuli
The skin contains a large number of nerve endings and receptors that detect stimuli related to temperature, touch, pressure, and pain. Specialized nerve fibers in the dermis, the layer of skin beneath the epidermis (the outermost skin layer), act as receptors for the sensations of pain, temperature, pressure, and touch. The locations of these nerve endings vary. The receptors for touch (also called tactile receptors) are closer to the epidermis, whereas the receptors for pressure are deeper within the dermis.
excertion
During perspiration, the sweat glands flush small amounts of waste products composed of water, salt, and organic compounds out of the body. (Organic compounds are the chemical compounds that make up living organisms.)
epidermis
(EP-ih-DER-mis) forms the outermost layer of the skin. Layers of epithelial (EP-ih-THEE-lee-uhl) tissue composed of densely packed cells make up the epidermis. These epithelial tissues cover the surface of the body and also line internal organs and cavities. One specialized type of epithelial tissue is the mucous membrane, which protectively lines any body cavity that opens to the outside world (for example, the nasal passage).
keratin
(KEER-uh-tin), a fibrous, water-repellent protein. Soft keratin is the primary substance of the epidermis. Hard keratin is found in hair and nails. The epidermis also includes special cells called melanocytes (MEL-uh-noh-sights). These cells contain and produce dark brown-to-black pigments called melanin (MEL-uh-nin). Melanin is responsible for the skin’s pigmentation, or color. Melanin also helps protect skin against the harmful ultraviolet rays of the sun.
dermis
also called the corium, lies directly below the epidermis. The dermis is made up of connective tissue, blood and lymphatic vessels, nerve fibers, hair follicles, and sebaceous and sweat glands. Sebaceous (suh-BAY-shus) glands are tiny glands in the skin that secrete sebum (SEE-bum), an oily substance, into the hair follicles. The hair follicles are tiny secretory (suh-KREE-toh-ree) cavities from which hair grows. Sebum lubricates the skin and hair.
subcutaneous layer
or hypodermis (HIGH-poh-DER-mis), is the deepest layer of the skin. Located below the dermis, the subcutaneous layer connects the skin to the surface muscles. It is composed of lipocytes (LIP-oh-sights), or cells that manufacture and store fat. Functionally, this layer of skin provides heat insulation and protects the deeper tissues of the body.
glands
The first type of accessory organ found in skin is the gland. A gland is a cell, or group of cells, that secretes select substances within or out of the body. Two types of glands—sebaceous and sweat glands—are found in the skin.
subcutaneous glands
located in the dermal layer of the skin over the entire body, except for the palms (hands) and the soles (feet). Sebaceous glands secrete an oily substance called sebum, which contains lipids. Lipids are a group of organic compounds that consist of fat, are greasy to the touch, and are insoluble (incapable of dissolving in water). Lipids lubricate the skin and minimize water loss. In skin, sebum travels through ducts that open into the hair follicles. Because sebum is slightly acidic, it discourages the growth of bacteria on the skin.
collagen
(KAH-luh-jen), a fibrous protein found in skin, bone, cartilage, tendons, and ligaments, makes up the connective tissue of the dermis. Connective tissue gives skin its shape, strength, and elasticity. The word collagen comes from the Greek word kolla, which means “glue.” This is an appropriate description of collagen fibers, which are tough and resistant but also flexible. These fibers support and protect the blood and nerve vessels that pass through the dermis.
Nails and parts
The third accessory organ of the skin is the nail. Nails are made of hard keratin. Fingernails cover the dorsal surface of the last bone of each finger, and toenails cover the superior surface of each toe (Figure 3.3). Many health disorders result in altered growth and appearance of the nails.
The basic structures of the nail are as follows:
The nail plate, or nail body, is the hard, translucent part of the nail. It is closely molded to the surface of the underlying tissue.
The cuticle (KYOO-tih-kuhl) is a narrow band of epidermal tissue attached to the surface of the nail, at the base and sides of the nail plate.
The nail root is the area of the dermis on which the nail rests. It fastens the nail to the finger or toe by fitting into a groove in the skin.
The lunula (LOON-yoo-luh) is the semilunar (half-moon-shaped), white area at the proximal end of the nail. The lunula is generally most prominent in the thumbnail.
sweat glands
are tiny, coiled glands located in the dermis. They are found on almost all exterior body surfaces. Sweat glands extend up through the epidermis, where they end in tiny openings called pores on the skin’s surface. Sweat glands are most abundant in the palms of the hands and soles of the feet. The sweat, or perspiration, secreted by the sweat glands contains 99 percent water and 1 percent salt and metabolic waste products. The act of perspiring, or secreting sweat, cools the body as the sweat evaporates into the air. You might be surprised to know that sweat is colorless and odorless. The odor produced when sweat collects on the skin is due to the interaction of sweat with bacteria on the skin.
Hair
Another type of accessory organ in the skin is hair. Your hair is made up of fibers, which are composed of tightly fused, dead protein cells filled with hard keratin. Each strand of hair grows from a root in the follicle. Melanocytes surround the core of each hair shaft. These melanocytes determine the color of your hair. Bundles of very small muscle fibers, called arrector pili (uh-REK-ter PIGH-LIGH), attach to the hair follicles. When you are cold or frightened, the arrector pili muscles contract, causing the hair on your skin to stand erect. The result is goose bumps on your skin.
acne
Inflammatory disorder of the sebaceous glands that produces pimples on the skin.
albinism
An inherited condition that prevents the normal production of melanin, resulting in extremely pale skin and white hair.
Alopecia
Hair loss that results from genetics, normal aging, illness, or drugs used to treat certain diseases.
1st degree burn
A skin burn characterized by superficial epidermal injury; erythema (EER-ih-THEE-muh), or redness; hyperesthesia (HIGH-per-es-THEE-zee-uh), or increased sensitivity, especially to touch; and no blisters. Example: sunburn (Figure 3.4A).
burn
Injuries to skin tissue caused by prolonged heat contact.
2nd degree burn
Skin burn characterized by epidermal and dermal injury, erythema, blisters, and hyperesthesia (Figure 3.4B).
3rd degree burn
Skin burn in which the epidermis and dermis are destroyed; this type of burn produces severe hyperesthesia or anesthesia (numbness), depending on the degree of nerve damage
cicatrix
A scar left by a healed wound.
cyanosis
Blue or purple discoloration of the skin or mucous membranes due to insufficient blood oxygen or poor circulation. Many circulatory and respiratory conditions produce cyanosis.
ecchyomus
Black-and-blue or purplish bruise caused by ruptured blood vessels beneath the skin.
gangrene
Necrosis (nuh-KROH-sis), or death, of tissue due to loss of blood supply, followed by bacterial infection (Figure 3.5).
eczema
Acute or chronic inflammatory skin disease characterized by erythema, itchiness, and edema (uh-DEE-muh), or swelling. Also called dermatitis. May occur alone or in conjunction with another disease.
impetigo
Bacterial infection of the skin characterized by vesicles (small, fluid-filled sacs), pustules (small, pus-filled blisters), and crusted-over lesions.
lesions, cancerous
An area of malignant (cancerous) tissue.
keloid
An abnormally raised, thickened scar
basal cell sarcoma
Commonly slow-growing, malignant tumor of the basal cell layer of the epidermis; seldom metastasizes, or spreads to other sites in the body
Kaposi’s sarcoma
Malignant cancer that causes erythematous (EER-ih-THEM-uh-tus) (red) or purplish patches in the lining of the mouth, nose, and throat or in other organs and tissues; a disease often seen in patients with AIDS.
squamous cell sarcoma
Malignant tumor of the squamous epithelial cells of the epidermis. This tumor may grow in other organs lined with epithelial cells (for example, the mouth, lungs, or cervix).
