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Chapter 6 A & P
Integumentary System
Term | Definition |
---|---|
The skin | 1. composed of several kinds of tissues 2.a protective covering that prevents many harmful substances from entering the body 3. retards water loss and helps regulate body temperature |
The skin (continued) | 4.houses sensory receptors and contains immune system cells 5. synthesizes vitamin D and excretes a small amount of waste products. |
two distinct layers of skin | 1. epidermis 2. dermis |
epidermis | 1.outer layer 2. composed of stratified squamous epithelium |
dermis | 1. inner layer 2. made up of connective tissues, muscle tissue, nervous tissue, and blood |
basement membrane | separates the two skin layers |
subcutaneous layer | 1. beneath the dermis 2. composed of loose connective tissues and adipose tissues 3. contains major blood vessels that supply the skin |
No sharp boundary separates the dermis and subcutaneous layer | because the fibers of the dermis are continuous with the fibers of the subcutaneous layer |
adipose tissue of the subcutaneous layer | insulates the body |
epidermis | lacks blood vessels |
stratum basale | 1. deepest layer of the epidermis 2. nourished by blood vessels in the dermis 3. Cells can divide and grow because they are nourished so well |
When new cells enlarge | they push old epidermal cells away from the dermis toward the surface of skin |
The farther the cells are moved | the poorer their nutrient supply becomes and eventually they die |
keratinocytes | 1. Older skin cells 2. held together with desmosomes |
Keratinization | 1.the accumulation of keratin in epidermal cells which hardens the epidermis 2. result is many layers of tough, tightly packed cells accumulate in the epidermis |
stratum corneum | outermost layer of the epidermis |
thickest epidermis | palms of the hands and the soles of the feet |
Most areas of epidermis | have 4 layers |
four layers (Deepest to outermost) | 1. stratum basale 2. stratum spinosum 3. stratum germinativum 4. stratum corneum |
stratum lucidum | An additional layer is in thickened skin of the palms and soles |
production of epidermal cells (Healthy skin) | balanced with loss of dead cells from the stratum corneum |
rate of cell division increases | where the skin is frequently rubbed or pressed |
Calluses | a thickening of the stratum corneum |
Corns | keratinized conical masses on the toes. |
melanocytes | 1. Specialized cells in the epidermis produce melanin 2. lie in the stratum basale and in the underlying connective tissues of the dermis |
Melanin | 1. provides skin color 2. absorbs UV radiation |
cytocrine secretion | a process by which the extensions of melanocytes transfer melanin granules to epidermal cells |
The boundary between the dermis and epidermis is | uneven because the epidermis projects inward and the dermis has papillae between the ridges of the epidermis. |
Fingerprints form | from the undulations of the dermis and epidermis at the distal end of the palmar surface of a finger |
dermis | 1. binds the epidermis to the underlying tissues 2. largely composed of irregular dense connective tissue that includes tough collagenous fibers & elastic fibers in a gel-like ground substance |
dermis (continued) | 3. contains smooth muscles that can wrinkle the skin of the scrotum. |
smooth muscle of the skin | associated with hair follicles |
skeletal muscles | In the face are anchored to the dermis |
Nerve cell | processes are scattered throughout the dermis |
Pacinian corpuscles | stimulated by heavy pressure |
Meissner’s corpuscles | stimulated by light touch |
melanocytes | Regardless of racial origin, all people have about the same number in their skin |
Differences in skin color | 1. result from the differences in the amount of melanin melanocytes produce 2. The more melanin produced, the darker the skin 3. The distribution and size of pigment granules within melanocytes |
Environmental factors | 1. sunlight, ultraviolet light from sunlamps, and X-rays affect skin color 2. stimulate melanocytes to produce more pigment and transfer it to nearby epidermal cells within a few days |
Tans | fade as pigmented epidermal cells become keratinized and wear away |
When blood is well oxygenated | the blood pigment hemoglobin is bright red and the skin of light-complexioned people appears pink |
When blood oxygen concentration is low | hemoglobin is dark red and the skin appears bluish |
If dermal blood vessels are dilated | more blood enters skin and skin appears pinkish or reddish |
If dermal blood vessels are constricted | more blood enters the dermis, and causes reddening the skin of a light-complexioned person |
Carotene | 1. a yellow-orange pigment found in certain vegetables 2. can give skin a yellowish color |
Hair | 1. present on all skin surfaces except the palms, soles, lips, nipples, and parts of external reproductive organs 2. composed of dead epidermal cells |
hair follicle | 1. a group of epidermal cells at the base of a tubelike depression in the dermis of skin 2. extends from the surface of skin into the dermis |
hair root | the portion of hair embedded in skin |
hair papilla | 1.a projection of connective tissue at the end of the hair follicle. 2. It contains blood vessels |
hair shaft | the portion of hair that extends from the surface of skin |
Baldness | results when hairs fall out and are not replaced |
hair color | Genes determine by directing the type and amount of pigment that epidermal melanocytes produce |
Dark hair | has more melanin than blond hair |
White hair of people with albinism | lacks melanin |
Red hair | contains an iron pigment called trichosiderin |
Hairs appear gray | from a mix of pigmented and unpigmented cells |
arrector pili muscle | 1. a band of smooth muscle 2. attaches to hair follicles |
Goose bumps | produced when arrector pili muscles contract |
Nails | 1. protective coverings on the ends of fingers and toes 2. consists of a nail plate that overlies a surface of skin called the nail bed |
lunula of a nail | the whitish, thickened, half-moon shaped region at the base of a nail plate with the most active growth |
Sebaceous glands | 1. contain groups of specialized epithelial cells and are associated with hair follicles 2. holocrine glands and their cells produce sebum |
Sebaceous glands (continued) | 3. not found on palms and soles 4. open directly onto the surface of the skin in some regions, such as the lips, corners of the mouth, and parts of the external reproductive organs |
Sebum | 1. a mixture of fatty material and cellular debris 2. secreted into hair follicles and helps keep hair and skin soft, pliable and waterproof |
sudoriferous glands | 1. sweat glands 2. consists of a tiny tube in the dermis or superficial subcutaneous layer |
eccrine glands | 1. most numerous sweat glands 2. respond to body temperature elevated by environmental heat or exercise 3. common on the forehead, neck, and back |
pore | the opening of a sweat gland duct |
Sweat | contains water, wastes, and salts |
Apocrine glands | 1. become active at puberty 2. can wet certain areas of skin when a person is nervous or stressed. 3. most numerous in the axillary regions, groin, and around the nipples |
Ceruminous glands | of the external ear canal secrete ear wax |
Mammary glands | secrete milk |
Regulation of body temperature | important because even slight shifts can disrupt the rates of metabolic reactions |
A normal temperature of deeper body parts | remains close to 37oC |
Heat | a product of cellular metabolism |
When body temperature rises above the set point | nerve impulses stimulate structures in the skin and other organs to release heat |
During physical activity | active muscles release heat, which the blood carries away |
When warmed blood reaches the hypothalamus | muscles in the walls of dermal blood vessels relax |
As dermal blood vessels dilate | heat escapes to the outside world |
Skin reddens | because dermal blood vessels are dilated |
radiation | 1. The primary means of body heat loss 2. the spread of infrared heat from warm surfaces to cooler surroundings |
Conduction | the movement of heat into molecules of cooler objects |
Convection | the continuous circulation of air over a warm surface |
Evaporation | the change of a liquid to a gas |
When sweat evaporates | it carries heat away from the skin surface |
When body temperature falls below the set point | muscles of dermal blood vessels constrict which decreases the flow of blood through the skin. |
When body temperature falls | sweat glands become inactive |
When body temperature continues to fall | small groups of muscles contract rhythmically to produce shivering |
Hyperthermia | a rise in body temperature |
If air temperature is high | heat loss by radiation is less effective |
Hypothermia | 1. a low body temperature 2. can result from prolonged exposure to cold or as part of an illness 3.can lead to mental confusion, lethargy, and loss of consciousness |
higher risk for developing hypothermia | Elderly, very thin individuals, homeless and the very young |
Inflammation | 1. a normal response to injury or stress 2. blood vessels dilate and become more permeable |
Inflamed skin | may become reddened, swollen, warm, and painful to the touch |
The dilated blood vessels | provide the tissues with more nutrients and oxygen, which aids healing |
The specific events of healing depend | on the nature and extent of the injury |
If a break in the skin is shallow | epithelial cells are stimulated to divide more rapidly than normal |
If a cut extends into the dermis or subcutaneous layer | blood vessels break and the escaping blood forms a clot |
A clot | consists mainly of fibrin, plasma, blood cells, and platelets. |
A scab | a blood clot and dried fluids |
Fibroblasts | migrate into the injured area and begin forming new collagenous fibers that bind the edges of the wound together |
Connective tissue matrix | releases growth factors that stimulate certain cells to divide and regenerate damaged tissues |
As healing continues | blood vessels extend into the area beneath the scab |
Phagocytic cells | remove dead cells and other debris |
A scar | results when the wound is extensive |
A granulation | consists of a branch of a blood vessel, and a cluster of collagen-secreting fibroblasts |
A first degree burn | one that only affects the epidermis |
A second degree burn | 1.one that affects a part of the dermis and epidermis 2. Blisters appear in second degree burns 3. depends on accessory structures of the skin that survive the burn |
A third degree burn | 1. one that destroys the epidermis, dermis, and the accessory structures 2.the skin becomes dry and leathery |
A third degree burn (continued) | 3. If extensive, treatment may involve removing a thin layer of skin from an unburned region of the body and transplanting it to the injured area. |
An autograft | a graft from the same person |
A homograft | a graft from a cadaver |
Skin substitutes | 1. amniotic membranes 2. membranes of silicone 3. polyurethane 4. nylon |
The treatment of a burn patient requires estimating | the extent of the body’s surface that is affected |
the rule of nines | 1. physicians use estimate 2. divides the skin’s surface into 11 areas of 9% each |
Aging skin affects | 1. appearance 2. temperature regulation 3. vitamin D production |
Age spots or liver spots | patches of pigments |
The dermis becomes reduced as | synthesis of the connective tissue proteins collagen and elastin slows |
Wrinkling and sagging skin | skin result from the shrinking of the dermis and loss of fat from the subcutaneous layer |
Skin becomes drier | because sebaceous glands produce less oil |
Slowed melanin production | causes gray or white hair |
Nail growth is impaired | because the blood supply to the nail beds is diminished |
Sensitivity to pain and pressure | diminishes with age |
An older person is less able to tolerate heat | because the sweat glands and hair follicles shrink, and the number of dermal blood vessels decreases |
Vitamin D | necessary for bone tissue to absorb calcium |