A&P Review for Chapter 6: Integumentary System

Review for Chapter 6 Integumentary System Know the following terms: Epiabove/over Derm- skin Cut- skin Seb- grease Sarco- flesh - Know the major functions of skin, hair, nails, sweat glands, sebaceous glands. Skin- Protection, covering, prevents some water loss, contains sensory receptors. Excretes some wastes, helps produce vitamin D, and helps regulate body temperature. Hair- functions as a thermal insulator. 3 parts: Hair bulb (dividing cells), hair root, hair shaft (dead, epidermal cells) Nails- Protective coverings on ends of fingers and toes. 3 parts: Nail plate, nail bed, and lunula. Nails grow from the nail matrix. Sweat glands- control body temperature. Sebaceous glands- Produce sebum, which consists of fatty material and cellular debris. Sebum keeps hair and skin soft and waterproof. Excess sebum can result in acne. - What causes goose bumps? The arrector pili. The muscles contract and pull the hair erect. - What proteins waterproof the skin? Keratin. A tough waterproof, fibrous protein made and stored in the cells. - Know how skin helps regulate body temperature (e.g. sweating, vasodilation, arrector pili function, etc.). When body temp rises vasodilation (widening of blood vessels) of the dermal blood vessels occurs, sweat glands are activated specifically the Eccrine (merocrine) glands because they are the most numerous and respond to elevated body temperature. When body temp reduces vasoconstriction occurs (constriction of blood vessels). Sweat glands become inactive and muscles contract involuntarily (shivering). The arrector pili also contracts to increase body temp. It is a tiny muscle attached at the base of a hair follicle, it contracts all at once causing goosebumps and hair to stand up straight. - Know the major types of tissues in the dermis and epidermis. Epidermis- Stratified squamous epithelium (avascular) Dermis- Connective tissue. - Which layer of skin contains blood vessels? Dermis - Which layer of skin contains melanocytes? What do melanocytes do? Epidermis. Melanocytes are located in the stratum basale. They produce the dark pigment, melanin. They absorb UV light from sunlight and provide skin color. - Where is the hypodermis? What does the hypodermis do? Hypodermis is beneath the dermis. It is areolar and adipose connective tissue. It's not considered part of the skin. It contains blood vessels that supply skin and is the insulating layer. - Know the differences between eccrine vs. apocrine sweat glands. Eccrine (merocrine glands)- most numerous. Secrete by exocytosis. Respond to elevated body temperature. Apocrine sweat glands- Axillary and groin areas. Secrete cytoplasm by shedding. Respond to emotions, pain, and cause body odor. - What part of hair is embedded in skin? What part of hair extends past the surface of skin? The root of hair is embedded in the skin. The shaft of hair extends past the surface of the skin. - Know the importance of the stratum basale vs. stratum corneum sub-layers of the epidermis. Stratum basale- Where the skin's most important cells called keratinocytes are formed before moving up to the epidermis and being shed into the environment as dead skin cells. deepest layer of epidermis. It is nourished by blood vessels in dermis. As the cells grow, they migrate toward the free surface, away from nutrient supply. As they migrate, older cells, keratinocytes begin to flatten and die. Stratum corneum- The stratum corneum functions to form a barrier to protect underlying tissue from infection, dehydration, chemicals and mechanical stress. Desquamation, (the process of cell shedding from the surface of the stratum corneum,) balances proliferating keratinocytes that form in the stratum basale. Stratum corneum is part of keratin, which is tough, fibrous, waterproof protein made and stored in cells. As the cells reach the outer surface they become tightly packed, develop desmosomes, and form the outer layer A.K.A. stratum corneum. The cells are eventually shed from skin surface, they are thickest on palms and soles. - Know the different kinds of burns and skin cancers we described. Burns- classified by depth or width of tissue damage (rule of 9). Superficial , partial- thickness (first degree) burn- injuries only to epidermis, as in sunburn; redness, heat, inflammation. Healing takes days-weeks, no scarring. Deep, partial-thickness (second degree) burn- Destroys epidermis and some dermis, as in burn from hot liquid. May blister, healing varies with severity of the burn and stem cell survival. Stem cells in hair follicles and glands can help regenerate skin. Usually recovers completely, no scarring. Full-thickness (third degree) burn- Destroys epidermis, dermis, accessory structures cause charring. Results from prolonged exposure to heat, flames, hot liquids. Some healing from margins. Often requires skin graft, skin substitutes. Indoor tanning and skin cancer- exposure to sunlight or a tanning bed causes melanocytes to produce more melanin and skin darkens. Tanning bed uses UV radiation that can overwhelm the body's natural protective responses against skin cancer. Example- Basal cell carcinoma and squamous cell carcinoma arise from epithelial cells in skin (skin cancer). Melanomas arise from melanocytes. Melanomas are least common (4%) skin cancers, but cause 80% of skin cancer deaths.