Visual Anatomy & Physiology Ch 5 – Flashcards
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integument
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skin
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integumentary system
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skin; includes two major components: cutaneous membrane and accessory structures
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cutaneous membrane
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includes epidermis and dermis
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functions of integumentary system
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1 - protection; 2 - vitamin D3 synthesis; 3 - excretion; 4 - sensation; 5 - temperature regulation; 6 - produce melanin (protection from ultraviolet radiation from sun); 7 - produce keratin (protection from abrasion and serves as water repellent); 8 - stores lipids
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layers of skin
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epidermis dermis hypodermis
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epidermis
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several layers (strata) of keratinocytes; consists of stratified squamous epithelial tissue
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epidermal ridges
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deep layers of epidermis that extend into dermis and are adjacent to dermal papillae; increase surface area for binding of dermis to epidermis
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dermal papillae
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upper layers of dermis that project into epidermis; increase surface area for binding of dermis to epidermis
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thin skin
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covers most of body surface; has four layers: stratum corneum, stratum ganulosum, stratum spinosum, and stratum basale
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thick skin
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found on palms of hands and soles of feet; has five strata instead of four: stratum corneum, status lucidum, stratum ganulosum, stratum spinosum, and strum basale
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stratum corneum
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uppermost layer of epidermis; exposed surface of skin; 15-30 layers of kerotinocytes; water resistant but not water proof
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keratin
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fluid inside kerotinocytes
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insensible perspiration
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water from interstitial fluid that slowly penetrates to the epidermal surface and evaporates; person does not see or feel this water loss; about 1 pint of water per day
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sensible perspiration
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fluid produced by active sweat glands; person is usually aware of sweating
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stratum lucidum
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"clear" layer of epidermis found only in thick skin under stratum corneum in epidermis; flattened, densely-packed cells filled with keratin and keratonhyalin
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stratum granulosum
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"grainy" layer of epidermis that has 3-5 layers of keratinocytes that have stopped dividing
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stratum spinosum
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"spiny" layer of epidermis that has 8-10 layers of kerotinocytes bound together by desmosomes; also contains dendritic (Langerhans) cells
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stratum basale
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bottom layer of epidermis containing basal cells and Merkel cells
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basal cells
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stem cells found in stratum basale of epidermis that divide to create new kerotinocytes
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Merkel cells
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cells found in stratum basale that are involved with touch sensation
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papillary layer
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upper layer of dermis consisting of areolar connective tissue
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reticular layer
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lower layer of dermis consisting of dense irregular connective tissue
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hypodermis
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also called subcutaneous layer or superficial fascia; separates skin from deeper organs; not part of the integument (skin); consists of areolar and adipose connective tissue
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touch receptors of skin
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convey sensations from the skin; include many different types such as free nerve endings, tactile discs, Meissner's corpuscles, lamellated corpuscles, and Ruffini corpuscles
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keratinocytes
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epithelial cells that produce keratin; continuously produced by stem cell division in deep layers of epidermis and shed at exposed surface of skin
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melanocytes
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epidermal cells that produce melanin; packaged in melanosomes; found in stratum basal
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dendritic cells
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Langerhans cells; cells in stratum spinosum layer of epidermis that defend against microorganisms and superficial skin cancers
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collagen fibers
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dermal cells and fibers that are very strong
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elastic fibers
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dermal cells and fibers that permit stretching
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skin color
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Influenced by presence of pigments, degree of dermal circulation, and thickness and degree of keratinization in epidermis
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skin color pigments
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melanin and carotene
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melanin
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brown, yellow-brown, or black pigment in skin produced by melanocytes; absorbs ultraviolet radiation to cause tanning; skin color is due to level of melanin synthesis rather than due to number of melanocytes
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carotene
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orange-yellow pigment that accumulates in epidermal cells
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hemoglobin
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red pigment found in red blood cells
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albinism
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skin color condition due to genetic lack of melanin; have normal number of melanocytes, but don't produce melanin
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cyanosis
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blue skin color condition due to decreased oxygen in blood; most obvious in lips or beneath fingernails
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skin cancer
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most common type of cancer in people
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cuticle (hair)
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outermost hair layer; consists of daughter cells produced at edges of hair matrix; contains hard keratin
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cortex (hair)
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intermediate hair layer of daughter cells deep to the cuticle; contains hard keratin
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medulla (hair)
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innermost hair layer; consists of daughter cells formed at center of hair matrix; contains soft keratin
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hair matrix
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consists of a layer of basal cells at base of hair bulb and in contact with hair papilla; germinative cells that produce hair; as cells divide, daughter dells are pushed toward surface
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hair shaft
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hair visible on surface of skin; begins deep within hair follicle
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hair root
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portion of hair that anchors it into skin; extends from base of hair follicle to point where hair shaft loses connection to walls of follicle
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internal root sheath of hair follicle
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surrounds hair root
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external root sheath of hair follicle
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consists of epithelial cells, extends from skin surface to hair matrix
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arrector pili muscle
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smooth muscle that contracts to pull hair erect
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root hair plexus
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sensory nerves surrounding base of each hair follicle; allows for felling of movement of hairs
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hair growth cycle
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growing and shedding of hair; active phase - hair grows continuously; resting phase - hair loses its attachment to follicle and becomes a club hair; scalp hair grows for 2-5 years
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nail body
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visible portion of nail; made up of dead, tightly compressed cells packed with keratin
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nail root
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portion of nail lying underneath skin; place where nail production occurs
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lunula
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pale crescent area of nail near root; coloring is caused by obscuring of dermal blood vessels
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nail bed
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epidermis beneath nail
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eponychium
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also called cuticle; part of stratum corneum of nail root that extends over exposed nail
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hyponychium
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thickened part of stratum corneum that lies underneath the free edge of nail
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psoriasis
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condition marked by rapid stem cell division in the stratum basale; can show up as pitted and distorted nails
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age related changes in integument
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1 - fewer melanocytes 2 - epidermis thins and dries out 3 - decreased perspiration 4 - gray/white hairs 5 - diminished immune response 6 - fewer hairs 7 - reduced blood supply 8 - thinning dermis 9 - slower skin repair 10 - altered hair and fat distribution
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epidermis thins
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basal cell activity declines; makes elderly more prone to injury, skin tears, and skin infections
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decreased perspiration
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decreased merocrine sweat gland activity; can lead to easier over-heating
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epidermis dries out
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decreased sebaceous gland secretion
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fewer melanocytes
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melanocytes become less active and skin becomes very pale; causes increased risk of sunburn
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diminished immune response
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decreased number of dendritic cells; may promote skin damage or infection
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thinning dermis
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makes skin weaker and less resilient; causes sag gin and wrinkling especially in areas exposed to sun
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reduced blood supply
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decreased blood flow to dermis can cause person to feel cool even in warm room; combined with reduced sweat gland function, can lessen ability of elderly to lose body heat during exertion and lead to heat exhaustion
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slower skin repair
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extended time needed for skin to heal after injury
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fewer hairs
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decreased number of active hair follicles; decreased melanocyte activity makes hairs grey or white
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altered hair and fat distribution
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as sex hormone levels decline, gender differences n hair and body fat distribution fade
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circulating hormones that affect integument
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1 - glucocorticoids 2 - thyroid hormones 3 - sex hormones 4 - growth hormone 5 - growth factors
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glucocorticoids
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steroid hormone released during times of stress; loosen connections between keratinocytes and reduce effectiveness of epidermis as barrier to infection
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thyroid hormones
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maintain blood flow to subpapillary plexus
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subpapillary plexus
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capillaries supplying dermis with blood flow
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sex hormones
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stimulate epidermal cell divisions to increase epidermal thickness and accelerate wound repair
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growth factors
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compounds that stimulate cell growth and cell division
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epidermal growth factor
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peptide growth factor that effect epithelia throughout body; produced by salivary glands and glands of duodenum (initial segment of small intestine); promotes basal cell division, accelerates keratin production, stimulates epidermal development and repair, and stimulates activity and secretion by epithelial glands
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growth hormone
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stimulates fibroblast activity and collagen synthesis; also stimulates basal cell divisions, thickens epidermis, and promotes wound repair
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vitamin D production
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UV radiation in sunlight → conversion of a steroid into cholecalciferol (Vitamin D3) in skin → conversion of cholecalciferol to calcitriol in the liver → absorption of calcium and phosphorus in small intestine to aid in bone growth and maintenance
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rickets
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condition in growing child that results in flexible, poorly mineralized bones; due to lack of sun exposure and vitamin D3 in diet
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4 phases of skin regeneration after injury
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1 - inflammatory phase 2 - migratory phase 3 - proliferation phase 4 - scarring phase
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inflammatory phase
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initial phase of skin regeneration after injury; bleeding occurs at site of injury and mast cells release histamine to cause swelling, redness, heat (warmth), and pain
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migratory phase
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second phase of skin regeneration that occurs several hours after initial injury; blood clot (scab) forms on surface to resist entry of microorganisms → macrophages phagocytize debris and pathogens → cells of stratum divide rapidly and migrate to edges of wound to replace missing epidermal cells; granulation tissue (combination of blood clot, fibroblasts, and extensive capillary network) starts to form if wound is extensive
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proliferation phase
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third phase of skin regeneration that occurs about one week after initial injury; epidermal cells migrate underneath scab to dissolve deeper portions of clot; fibroblasts produce collagen fibers and ground substance in dermis
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scarring phase
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final phase of skin regeneration that occurs several weeks after initial injury; epidermal repair is complete; scar tissue (inflexible, fibrous, noncellular tissue) completes repair process in dermis; tissue is never restored to original condition
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keloid
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raised, thickened mass of scar tissue at site of injury and surrounding area; happen most in people with dark skin; sometimes done intentionally as a form of body decoration
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dermis
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found between epidermis and hypodermic; consists of papillary layer of arelar tissue and a reticular layer of dense irregular connective tissue
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accessory structures of integumentary system
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hair, nails, and exocrine glands, blood vessels and nerve fibers support skin function; also known as epidermal derivatives, because they develop from epidermis during embryonic development
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cutaneous plexus
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network of arteries and veins connected to smaller vessels servicing the tissues of the integumentary system
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erythema
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redness and and inflammation at the surface of the skin
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first-degree burn
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burn involving only epidermis and causing redness (erythema) and swelling; type of partial thickness burn; includes most sunburns; skin reddens and can be painful
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second-degree burn
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burn involving epidermis and dermis that usually forms blisters, pain, and swelling; type of partial thickness burn; takes 1-2 weeks to heal
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third-degree burn
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burn involving entire thickness of skin, hypodermis, and subcutaneous tissue, muscle, and bone; causes scarring; less painful than second-degree burns because sensory nerves are destroyed; also called full thickness burn; requires skin grafting
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Skin functions affected by burns
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fluid and electrolyte balance, thermoregulation, protection form infection
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skin graft
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surgical procedure involving tissue transplant; used to treat serious burns
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rule of nines
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method used to calculate the total surface area involved in burns in which the body surface of an adult is divided into multiples of 9; head is 9%, each upper limb is 9%; trunk is 36%, genitalia are 1%; each lower limb is 18%; modify rule for children because their proportions are different
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autograft
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type of skin graft that uses tissue transplanted from the same person
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allograft
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type of skin graft that uses tissue transplant between members of the same species
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xenograft
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type of skin graft that uses tissue transplant from another species; example: pig skin
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skin cultivation
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recent advance in cell culturing that allows scientists to grow large sheets of epidermal cells for covering burned areas; alternative way to get tissue for skin grafts
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epithelial columns
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cords of epidermal cells that grow into the dermis and allow for development of hair follicles, sebaceous glands, and sweat glands
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hair follicle
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an accessory structure of the integument that produces body hair; a tube lined by stratified squamous epithelium that begins at surface of skin and ends at hair papilla
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terminal hairs
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Large, coarse, and often dark-colored hairs found on scalp or armpits
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vellus hairs
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Small, short, and delicate hairs found on general body surface
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hair bulb
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Place where hair growth begins at the expanded base of hair follicle
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club hair
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Hair that loses its attachment to the follicle and will soon be shed and replaced by a new hair
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basal cell carcinoma
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most common type of skin cancer; originates in stratum basal due to mutations caused by overexposure to UV radiation in sunlight; usually not life threatening
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malignant melanoma
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extremely dangerous type of skin cancer; cancerous melanocytes metastasize throughout lymphatic system; survival rate is largely dependent on how early the cancer is found and treated
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free nerve endings
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sensitive to touch and pressure and are found between epidermal cells
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tactile discs
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detect sensations of texture and steady pressure; found in deepest layer of epidermis
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Meissner's corpuscles
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detect sensations of delicate touch, pressure, and vibrations; found in papillary layer of dermis
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lamellated corpuscles
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sensitive to deep pressure and vibration; found in both dermal layers and hypodermis
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Ruffini corpuscles
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sensitive to pressure and stretching of skin; found in reticular layer of dermis
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lines of cleavage
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tension lines or Langer lines; parallel bundles of collagen and elastic fibers that resist forces applied to skin during movement; cut parallel to line of cleavage will have little scarring, whereas cut perpendicular to cleavage line will have considerable scarring
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skin functions affected by burns
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fluid and electrolyte balance, thermoregulation, protection from infection
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fluid and electrolyte balance
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even areas of body with partial thickness burns lose effectiveness as barriers to fluid and electrolyte losses; in full thickness burns, rate of fluid loss through skin may reach five times the normal level
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thermoregulation
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increased fluid loss means increased evaporative cooling; requires expenditure of more energy to keep body temperature within acceptable limits
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protection from infection
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dampness of epidermal surface--resulting from uncontrolled fluid loss--encourages bacterial growth; if skin is broken, infection is likely; widespread bacterial infection (sepsis) is leading cause of death in burn victims
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sepsis
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widespread bacterial infection; rotting of the skin
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soft keratin
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found in medulla or core of hair; flexible
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hard keratin
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found in cortex of hair; thick layers that give hair stiffness
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hair follicle structure
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includes internal root sheath, external root sheath, glassy membrane, and connective tissue sheath
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internal root sheath
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part of hair follicle that surrounds hair root and deeper portion of hair shaft; produced by hair matrix; cells disintegrate quickly
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external root sheath
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part of hair follicle consisting of epithelial cells; extends form skin surface to hair matrix
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glassy membrane
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thickened, clear basement membrane of hair follicle
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connective tissue sheath
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outermost part of hair follicle
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exocrine glands
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includes sebaceous glands and sweat glands; assist in thermoregulation, excretion of waste, and lubrication of epidermis
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sebaceous glands
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also known as oil glands; discharge an oily, lipid substance (sebum) into hair follicles that coat hair and adjacent area of skin
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sebum
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secretion from sebaceous glands; lubricates hair shaft, moisturizes surrounding skin, and inhibits goeth of bacteria
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sweat glands
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discharge merocrine and apocrine when contractions of myoepithelial cells squeeze the gland
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apocrine sweat glands
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type of sweat glands found in armpits, pubic region, and around nipples; secrete into hair follicles; produce body odor; strongly influenced by hormones
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merocrine sweat glands
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merocrine - found in most areas of skin; important for thermoregulation; secrete directly onto surface of skin
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nails
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thick sheets of keratinized epidermal cells that protect tips of fingers and toes
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lateral nail grooves
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side boundaries (depressions) of nail body
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lateral nail folds
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side boundaries (ridges) of nail body
