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skin

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the body's largest and heaviest organ. In adults, it covers an area of 1.5 to 2.0 m2 and accounts for about 15% of the body weight. It consists of two layers - because it houses many nerve endings and sensory organs he skin is vitally involved with sensation - the skin assist endocrine function by playing a role in vitamin D synthesis - skin contains the protein keratin and cellular junctions called desmosomes that confer a mechanical strength to the epidermis, which resists mechanical traumas such as punctured and abrasions - essential in sensing external stimuli

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epidermis

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one of two layers of the skin; a stratified squamous epithelium - constitutes the superficial layer of the skin, overlying the dermis - composed primarily of epithelial tissues - includes 4-5 strata of the skin - avascular - creates a water barrier with the environment - as a result of impermeable cellular junctions and water-proofing lipids, the epidermis functions in creating a barrier to some fluids - the layer of the epidermis are arranged in zones based upon the age of the keratinocytes - keratinocytes are the most numerous cells found in this layer - active cell division allows for the skin to regenerate quickly

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dermis

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The deeper of the two layers of the skin, underlying the epidermis and composed of fibrous connective tissue. one of two layers of the skin; a deeper connective tissue layer - the layer that is made into leather products after removal of more superficial and deeper tissues - contains the papillary and reticular layers - principally comprised of dense irregular connective tissue - includes hair follicles, glands, and blood vessels - components of the dermis: blood vessels, glands, fibers, nerve fibers - tissues types found in the dermis include: epithelial tissue, connective tissue, nervous tissue, muscular tissue - consists of two zones: the papillary layer and the reticular layer - collagen is the most common fiber type within the layer - oxygen and nutrients needed by the epidermal cells undergoing mitosis are acquired from blood vessels in the dermis

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hypodermis

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not part of the skin but is customarily studied in conjunction with it - not actually considered part of the skin - deepest layer - contains tissues associated with energy storage, thermal insulation and mechanical padding

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Thick skin

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it has sweat glands nut no hair follicles or sebaceous gland

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thin skin

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found everywhere except the palms of the hands, soles of the feet, fingertips and toe tips

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keratin

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a protein that is produced in the cells of the epidermis that improve its durability and resistance to infection

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defensive antimicrobial peptides

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dermcidin and defensins

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acid mantle

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protective acidic film that gives skin its slight acidity

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Vitamin D synthesis

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- would be impaired if a person was burned badly

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Sensation

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Conscious perception of a stimulus; pain, taste, and color, for example, are not stimuli but sensations resulting from stimuli.

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Thermoregulation

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Homeostatic regulation of the body temperature within a narrow range by adjustments of heat-promoting and heat-losing mechanisms. - through vasodilation in times of excessive heat, and vasoconstriction during times of cold the blood flow to the dermis aids the body through thermoregulation - in the process of thermoregulation, cutaneous nerve endings monitor the temp of the body surface

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thermoreceptors

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A neuron specialized to respond to heat or cold, found in the skin and mucous membranes, for example.

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Nonverbal communication

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facial muscles that insert on the collagen fibers of the dermis and move the skin.

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Transdermal Absorption

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The ability of the skin to absorb chemicals makes it possible to administer several medicines as ointments or lotions, or by means of adhesive patches that release the medicine steadily through a membrane.

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Stem cells

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Any undifferentiated cell that can divide and differentiate into more functionally specific cell types such as blood cells and germ cells.

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Keratinocytes

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- location: epidermis - exfoliate from the epidermal surface as tiny specks called dander

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melanocyte

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A cell of the stratum basale of the epidermis that synthesizes melanin and transfers it to the keratinocytes.

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Tactile (Merkel) cells

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sensing light touch - cells with a sensory role

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Dendritic (Langerhans) cells

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- macrophages (WBCs) that originate in the bone marrow and migrate to the skin - found in the stratum spinosum and the stratum granulosum

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stratum basale

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comprised of viable, single layer of cuboidal epidermal and columnar cells; contains the kertinocyte stem cells that replenish the exfoliated cells at the surface (5) - single layer of cuboidal epidermal cells that are actively mitotic and replace superficial cells - has stem cells, mlanoctes and tactile cells

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stratum spinosum

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towards the apical surface the kertinocytes cease cell division while at the deeper regions they can still undergo mitosis (4) - contain dendritic cells

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stratum granulosum

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is named for the presence of dark staining keratohylin granules which bind the cytoskeletal karatin filaments together (3) - contain dendritic cells - no longer mitotic

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keratohyalin granules

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coarse dark-staining granules found in karatinocytes in the stratum granulosum layer

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stratum lucidum

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which is present only on the soles of feet, hands, fingers and toes (2)

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eleidin

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found in cells of the stratum lucidum

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stratum corneum

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is made up of multiple layers of dead keratinocytes that regularly exfoliate (1) - fingernails and toenails are derivatives

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Life History of a Keratinocyte

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...

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Dermatophagoides

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(dust mites) thrives abundantly in pillows, mattresses, and upholstery—warm, humid places that are liberally sprinkled with edible flakes of keratin

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calluses or corns

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thick accumulations of dead keratinocytes on the hands or feet - mechanical stress from manual labor accelerates keratinocyte multiplication

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membrane-coating vesicles (lamellar granules)

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oily waxy stuff that helps with water proofing Lamellar granules release a lipid-rich secretion that is deposited in the spaces between cells of the stratum granulosum, stratum lucidum, and stratum corneum. The lipid-rich secretion acts as a water-repellent sealant, retarding loss of water and entry of foreign materials. found in keratinocytes in the stratum granulosum.

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filaggrin

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protein that binds the cytoskeletal keratin filaments together into coarse, tough bundles

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envelope proteins

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a very tough layer of envelope proteins just beneath the plasma membrane, resulting in a nearly indestructible protein sac around the keratin bundles.

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epidermal water barrier

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crucial to the retention of body wate

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exfoliate

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flake off

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dander

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keratinocytes exfoliate from the epidermal surface as tiny specks called dander

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Dandruff

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composed of clumps of dander stuck together by sebum (oil)

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dermal papillae

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an extension of the vascular system into the hair bulb - the wavy upward projections of he dermis at the dermis-epidermis boundary - in some areas of the body, the boundary between the dermis and the epidermis is irregular. the the wavy upward projections in this area of the dermis is called ...

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epidermal ridges

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downward waves of dermal papillae are extensions of the epidermis

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papillary layer

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1. Pertaining to or shaped like a nipple, such as the papillary muscles of the heart. 2. Having papillae, such as the papillary layer of the dermis. - areolar connective tissue

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reticular layer

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- part of the dermis is deeper and much thicker - consists of dense irregular connective tissue - the boundary between the papillary and reticular layers

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hypodermis (subcutaneous tissue)

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A layer of connective tissue deep to the skin; also called superficial fascia, subcutaneous tissue, or when it is predominantly adipose, subcutaneous fat. - acts as an energy reservoir and thermal insulation - highly vascular making it a prime injection site

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Subcutaneous fat

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is hypodermis composed predominantly of adipose tissue. It serves as an energy reservoir and thermal insulation. It is not uniformly distributed

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melanin

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the component of skin that is the primary determinant of skin color (Albinism) - melanin deposits in keratinocytes protect the body from UV damage - exposure to sunlight increases melanin production and darkening of the skin

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hemoglobin

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The red gas transport pigment of an erythrocyte. - imparts a pink color to healthy skin

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Carotene

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- when there is excess it is deposited in the stratum corneum and subcutaneous fat

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cyanosis

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A bluish color of the skin and mucous membranes due to ischemia or hypoxemia. - the blueness of the skin resulting from a deficiency of oxygen in the circulating blood

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Erythema

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abnormal redness of skin

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Pallor

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a pale or ashen skin color occurs when there is little blood flow through the skin

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Albinism

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a genetic lack of melanin that usually results in milky white hair and skin, and blue-gray eyes. Melanin is synthesized from the amino acid tyrosine by the enzyme tyrosinase. People with albinism have inherited a recessive, nonfunctional tyrosinase allele from both parents.

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jaundice

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A yellowish color of the skin, corneas, mucous membranes, and body fluids due to an excessive concentration of bilirubin; usually indicative of a liver disease, obstructed bile secretion, or hemolytic disease.

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hematoma

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A mass of clotted blood in the tissues; forms a bruise when visible through the skin. - transient manifestations of damage to the skin, a type of bruising

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friction ridges

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the structure that enhance sensitivity to texture by vibrating and stimulating lamellar corpusles in the skin when the fingertips stroke an uneven surface

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Flexion lines (flexion creases)

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- found on the surfaces of hands - the sites where the skin folds during flexion of the joints - the skin is tightly bound to deeper connective tissues along these lines

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Freckles

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flat melanized patches that vary with heredity and exposure to the sun

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mole (nevus)

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an elevated patch of melanized skin, often with hair. Moles are harmless and sometimes even regarded as "beauty marks," but they should be watched for changes in color, diameter, or contour that may suggest malignancy (skin cancer)

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hemangiomas

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patches of skin discolored by benign tumors of blood capillaries - capillary - port-wine - cavernous

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accessory organs (appendages)

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hair nails and cutaneous glands - organs are those that contribut functions to the main organ or system

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soft keratin

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the stratum corneum of the skin is made of pliable

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hard keratin

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the hair and nails are composed mostly of hard keratin - more compact than soft keratin and is toughened by numerous cross-linkages between the keratin molecules.

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pilus

answer

an individual hair

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hair follicle

answer

An oblique epidermal pit that contains a hair and extends into the dermis or hypodermis. "pocket" - two principal layers of the hair follicle are an epithelial and connective tissue root sheath

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Lanugo

answer

One (hair in a fetus)

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vellus

answer

Two (constitutes two-thirds of the hair in women and one tenth of the hair in men)

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Terminal hair

answer

Three (the predominant form of hair found on scalp)

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hair matrix

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(3) forms hair by mitotic cells; serves as hair's growth center - region of mitotically active cells that serves as the hair's growth center

question

bulb

answer

(4) a swelling at the base where the hair originates in the dermis or hypodermis

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root

answer

(2) the remainder of the hair within the follicle

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shaft

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(1) the portion above the skin surface. The only living cells of a hair are in and near the bulb

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dermal papilla

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(5) nourish hair cells

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medulla

answer

Tissue deep to the cortex of certain two-layered organs such as the lymph nodes, adrenal glands, hairs, and kidneys. - at the center of each hair and is loosely arrange core of cells and air spaces

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cortex (plural, cortices)

answer

The outer layer of some organs such as the adrenal gland, cerebrum, lymph node, and ovary; usually covers or encloses tissue called the medulla.

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epithelial root sheath

answer

is an extension of the epidermis and lies adjacent to the hair root

question

connective tissue root sheath

answer

derived from the dermis, surrounds the epithelial sheath and is somewhat denser than the adjacent dermal connective tissue

question

bulge

answer

the deep end of the follicle that serves as a source of stem cells for follicle growh

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hair receptors

answer

nerve fibers; hair receptors entwine each follicle and respond to hair movements

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piloerector muscle

answer

pilomotor muscle or arrector pili; conditions that commonly lead to contraction of these muscles are touch, cold, and fear - cause "goosebumps" by contractions

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hair cycle

answer

consisting of three developmental stages: anagen, catagen, and telogen

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anagen

answer

In this stage, stem cells from the bulge in the follicle multiply and travel downward, pushing the dermal papilla deeper into the skin and forming the epithelial root sheath. Root sheath cells directly above the dermal papilla form the hair matrix. Here, sheath cells transform into hair cells, which synthesize keratin and then die as they are pushed upward away from the papilla. The new hair grows up the follicle, often alongside an old club hair left from the previous cycle.

question

catagen stage

answer

mitosis ceases and the sheath cells below the bulge die

question

telogen

answer

resting period in which the papilla reaches the bulge

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alopecia

answer

occurs to some degree in both sexes and may be worsened by disease, poor nutrition, and emotional stress

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Pattern baldness

answer

the condition in which hair is lost from select regions of the scalp rather than thinning uniformly across the entire scalp. It results from a combination of genetic and hormonal influences

question

sex-influenced traits

answer

characteristics in which an allele is dominant in one sex and recessive in the other

question

hirsutism

answer

individuals with hormonal imbalances can exhibit excessive hairiness

question

guard hairs (vibrissae)

answer

the structures that guard the nostrils and ear canals, preventing foreign particles from entering these areas

question

nail plate

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hard part of the nail

question

free edge

answer

overhanging the tip of the finger or toe

question

nail body

answer

the visible attached part of the nail

question

nail root

answer

extends proximally under the overlying skin

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nail fold

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the surrounding skin rises a bit above the nail

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nail groove

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the nail fold is separated from the margin of the nail plate

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nail bed

answer

skin underlying the nail plate

question

hyponychium

answer

epidermis to the nail bed - the area of the epidermis that covers the nail bed

question

nail matrix

answer

the area of growth of the nail, located deep at the proximal end of the nail plate

question

lunule

answer

the white crescent area located over the nail matrix; free edge

question

eponychium (cuticle)

answer

the outermost part of the hair shaft - the narrow zone of dead skin that commonly overhangs the proximal end of the nail

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sudoriferous (sweat) glands

answer

- sweat secreting - eccrine - merocrine - secrete products via exocytosis - apocrine - mammary glands - secrete directly onto the skin surface - secretions are 99% water and slightly acidic pH - simple tubular structures - responsible for diaphoresis - secretion of pheromones

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Apocrine sweat glands

answer

- not active until puberty - secrete pheromones - found mostly in the area of pubic, axillary and beard hair - scent is meant to attract a potential mate - secrete sweat - utilize myoepithelial cells to secrete - utilize ducts to release sweat

question

sex pheromones

answer

chemicals that exert subtle effects on the sexual behavior and physiology of other people

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bromhidrosis

answer

disagreeable body odor; occasionally indicates a metabolic disorder, but more often reflects inadequate hygiene

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Merocrine (eccrine) sweat gland

answer

Pertaining to gland cells that release their product by exocytosis. - found distributed over entire body - thermorgulation - abundant in the hands, feet, and forehead - secrete sweat - utilize myoepithelial cells to secrete - utilize ducts to release sweat - MOST abundant glands in the body numbering 3 to 4 million in the adult skin

question

myoepithelial cells

answer

- found in apocrine and merocrine sweat glands - have contractile properties similar to smooth muscle

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insensible perspiration

answer

occurs when perspiration evaporates quickly so it is not noticed

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diaphoresis

answer

the term that describes the condition in which sweat is produced, causing noticeably wet skin during circulatory shock or exercise

question

Sebaceous glands

answer

- oil producing - holocrine - associated with hair follicles - sebum secreting secrete products via apoptosis - secrete products mostly onto hair follicles - lanolin - usually opens up into a hair follicle - coats the scalp hair with oil - blockage and infection can cause pimples - form of sudoriferous gland. - modified mammary glands. - found at the base of eyelash hairs.

question

sebum

answer

An oily secretion of the sebaceous glands that keeps the skin and hair pliable. (prevents hair and skin from becoming dry and brittle)

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Ceruminous glands

answer

- secretes earwax - coats gaurd hairs to improve their performance - simple, coiled, tubular - waterproofs the ear canal

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cerumen

answer

the external ear canal, where their secretion combines with sebum and dead epidermal cells to form earwax

question

mammary glands

answer

Milk-producing glands located in the breasts

question

mammary ridges

answer

milk lines;

question

polythelia

answer

the presence of additional nipples

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Acne

answer

Inflammation of the sebaceous glands, especially beginning at puberty; follicle becomes blocked with keratinocytes and sebum and develops into a whitehead (comedo) composed of these and bacteria; continued inflammation of follicle results in pus production and appearance of pimples, and oxidation of sebum turns a whitehead into a blackhead.

question

Dermatitis

answer

Any inflammation of the skin, typically marked by itching and redness; often contact dermatitis, caused by exposure to toxic foliage such as poison ivy.

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Eczema

answer

Itchy, red, "weeping" skin lesions caused by an allergy, usually beginning before age 5; may progress to thickened, leathery, darkly pigmented patches of skin.

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Psoriasis

answer

Recurring, reddened plaques covered with silvery scale; sometimes disfiguring; possibly caused by an autoimmune response; runs in families.

question

Rosacea

answer

red rashlike area, often in the area of the nose and cheeks, marked by fine networks of dilated blood vessels; worsened by hot drinks, alcohol, and spicy food.

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Seborrheic dermatitis

answer

Recurring patches of scaly white or yellowish inflammation often on the head, face, chest, and back; called cradle cap (a yellow, crusty scalp lesion) in infants. Cause unknown, but correlated with genetic and climatic factors.

question

Tinea

answer

Any fungal infection of the skin; common in moist areas such as the axilla, groin, and foot (athlete's foot). Misnamed ringworm because of the circular, wormlike growth pattern sometimes exhibited.

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Skin Cancer

answer

three types of skin cancer can be distinguished by the appearance of their lesions and zones of tissue injury

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lesion

answer

A circumscribed zone of tissue injury, such as a skin abrasion or myocardial infarction.

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Basal cell carcinoma

answer

- the most common type of skin cancer - seldom spreads to other tissues/ metastasizes - arises from the deepest layer of the epidermis and may invade the dermis

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Squamous cell carcinoma

answer

- arises from the superficial cells of the epidermis - raised, reddened scaley appearance - gone unnoticed it could spread to the lymph nodes

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Melanoma

answer

- if metastasized the deadliest skin cancer - arises from the cells that protect from UV light (melanocytes) - the least common skin cancer - caused by mutations commonly found in moles

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Burns

answer

the leading cause of accidental death. They are usually caused by fires, kitchen spills, or excessively hot bath water, but they also can be caused by sunlight, ionizing radiation, strong acids and bases, or electrical shock

question

eschar

answer

dead tissue associated with burns to the skin

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First-degree burns

answer

- seldom leaves scars - cause redness, slight edema, and pain - may heal in a few days - only effects the epidermis

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Second-degree burns

answer

- part of the dermis is involved - severe sunburns and many scalds - involves injury to the epidermis and the upper region of the dermis

question

partial-thickness burns

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first- and second-degree burns

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Third-degree burns

answer

- all of the dermis is effected - skin grafts may be required - sometimes muscle and bone are destroyed

question

full-thickness burns

answer

Third-degree burns because the epidermis, all of the dermis, and often some deeper tissues (muscle and bone) are destroyed

question

debridement

answer

the removal of burned skin; essential for infection control

question

autograft

answer

tissue is taken from one area of a person's body and grafted onto another area of their body

question

split-skin graft

answer

part of the dermis is left behind to proliferate and replace the epidermis that was removed—the same way a second-degree burn heals

question

isograft

answer

uses skin from an identical twin

question

allograft (homograft)

answer

a graft from any other person

question

heterograft (xenograft)

answer

a graft of tissue from a different species

question

immunosuppressants

answer

the immune reaction can be suppressed by drugs - lowers a person's resistance to infection, which is already compromised in a burn patient

question

skeletal muscle

answer

attachments to facial structures produce a wide variety of expressions and produce nonverbal communication with other individuals

question

normal or pathological (abnormal) variation in skin color

answer

ABNORMAL - oxygen deficiency results in blue-ish color - lack of tyrosinase result in in fair skin and hair - jaundice - hyper permeable capillaries result in blood in the dermis that shows through the skin - cyanosis NORMAL - genetically active melanocytes result in brownish skin (freckles) - genetically low number of active melanocytes resulting in fairer skin - ancestral exposure to UV radiation results in active melanocytes in descendents

question

burn treatment

answer

- Fluid replacement and infection control are the most critical aspects of emergency care for severe burns. - In order to avoid nourishing an infection, the patient should decrease caloric intake. - A patient may lose up to 75% of the blood plasma within hours. - Skin grafts are often required for third degree burns. - a burn patient would most likely need infection control

question

muscle tissue

answer

- two types: smooth and cardiac - One function of muscle tissue is to provide heat production.

question

epithelial tissue

answer

- simple squamous - stratified squamous - pseudostratified columnar - simple columnar

question

connective tissue

answer

- areolar - adipose - elastic cartilage - compact bone - hyaline cartilage

question

nervous tissue

answer

nervous

question

eyebrows

answer

enhance facial expression and keep sweat out of eyes

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moles

answer

are elevated patches of skin that are harmless and sometimes regarded as beauty marks

question

feature of skin that minimizes bacteria and fungi growth during an infection

answer

- the acid mantle inhibits microbial growth - the dryness of the skin inhibits microbial growth - the cells of the skin shed frequently

question

advertisement by hair color

answer

hair with contrasting colors are important among mammals for "advertising" the individual's species, age, sex, and individual identity

question

perspiration (sweat)

answer

- primary component = water - 99% water and has a pH of 4-6 - composition of sweat: acidic solution containing urea, potassium, sodium chloride and ammonia this composition contributes to the acid mantle and inhibits bacterial growth on the skin

question

skin markings

answer

include hematomas, creases and friction ridges

question

electrodesiccation

answer

the distriction of the cancerous lesion (skin cancer) by heat

question

three concentric regions of the hair from the outside to the inside

answer

cuticle, cortex, medulla

question

BRAF oncogene

answer

discovered by the Cancer Genome Project - oncogene responsible for melanoma in men - breast cancer

question

lipids

answer

the presence of a layer of lipids between the stratum spinosum and stratum granulosum facilitates water retention

question

dermtology

answer

the branch of medicine that deals with the integumentary system

question

cause blushing

answer

vasodilation of blood vessles

question

long term hypoxemia

answer

clubbed fingers are a sign

question

most tumors occur whee exposure to the sun is greatest

answer

head neck hands

Chapter Six: The Integumentary System – Flashcards

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