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A&P I, Chap. 6

Integumentary system

QuestionAnswer
Integumentary system Consists of the skin and its derivatives - nails, hair, sweat glands and sebaceous glands.
Integument - definition Is the skin covering the body. a.k.a. cutaneous membrane
Integument - function Barrier to the outside world. Visual indicator of our physiology and health. It's scientific study is called dermatology.
Integument tissue types (pt. 1) Surface covered by an epithelium. Underlying connective tissue - provides strength and resilience - contains smooth muscle associated with hair follicles.
Integument tissue types (pt. 2) Nervous tissue - provides information about touch, pressure, temperature and pain
Integument layers Epidermis - stratified squamous epithelium. Dermis - Deeper layer, primarily dense irregular connective tissue.
Subcutaneous layer Deep to dermis. Layer of alveolar and connective tissue. Termed subcutaneous layer or hypodermis. Not part of the integumentary system. Closely involved with structure and function of skin.
Integument epithelium characteristics Termed epidermis. Keratinized, stratified squamous epithelium. Consists of specific layers or strata.
Layers of the epithelium Deep to superficial: 1-stratum basale 2-stratum spinosum 3-stratum granulosum 4-stratum lucidum 5-stratum corneum
First three layers With living keratinocytes
Superficial two layers With dead keratinocytes
Stratum basale characteristics Deepest epidermal layer, a.k.a. basal layer, single layer of cuboidal to low columnar cells.
Stratum basale location Attached to underlying basement membrane - separates the epidermis from the dermis.
Stratum basale - cell types Keratinocytes, melanocytes, tactile cells
Keratinocyte characteristics Most abundant cells in epidermis. Found in all layers. Many keratinocyte stem cells present in this stratum basale layer.
Keratinocyte functions Divide to regenerate new cells. Replace old cells shed at the surface.
Keratinocyte Named derived from the synthesis of keratin - protein that strengthens the epidermis.
Melanocytes characteristics Scattered among the keratinocytes. Produce and store pigment (melanin) in response to ultraviolet light.
Melanocyte function Transfer pigment granules (melanosomes) into keratinocytes: accumulate around nucleus of keratinocytes, shield nuclear DNA from UV radiation, responsible for the darker tones of skin.
Tactile cells Also known as Merkel cells. Few in number. Sensitive to touch. When compressed, release chemicals - stimulate sensory nerve endings.
Stratum spinosum characteristics (pt. 1) Several layers of polygonal keratinocytes. Also known as spiny layer - named for spiny appearance on microscopy. Daughter cells from stratum basale pushed into this layer.
Stratum spinosum characteristics (pt. 2) Begin to develop into specialized, non-dividing keratinocytes - some in deepest level still dividing cells. Non-dividing keratinocytes attached by intercellular junctions - called desmosomes.
Epidermal dendritic cells a.k.a. (Langerhans cells) Often present in stratum spinosum and stratum granulosum. Immune cells that help initiate immune response. Responsive to pathogens and epidermal cancer cells.
Stratum granulosum characteristics Three to five layers of keratinocytes. Also known as granular layer. Superficial to the stratum spinosum.
Stratum granulosum (pt. 1) First layer of keratinization. Process where keratinocytes fill with keratin. Causes nucleus and organelles to disintegrate. Fully keratinized cell dead but structurally sound. Process not complete until more superficial layers.
Stratum lucidum characteristics (pt. 1) Two to three layers of keratinocytes. Translucent layer also known as clear layer. Superficial to the stratum granulosum.
Stratum lucidum characteristics (pt. 2) Found only on thick skin within the palms and soles. Filled with a translucent protein, eleidin - intermediate product in keratin maturation.
Stratum corneum characteristics (pt. 1) 20-30 layers of dead, interlocking keratinized cells. Cells anucleate and tightly packed. Plasma membrane enclosing keratin protein. Also known as the hornlike layer.
Stratum corneum characteristics (pt. 2) Most superficial layer of epidermis. Surface unsuitable for the growth of many microorganisms - secretions of exocrine glands also helping prevent growth.
Migration of keratinocytes Originate from stem cells in stratum basale. Migrate through strata to stratum corneum over two weeks - undergoing structural changes. Remain in stratum corneum another two weeks.
Thick skin On the palms of hands, soles of feet and surfaces of fingers and toes. All five layers of epidermal strata. Have sweat glands. No hair follicles or sebaceous glands. From 0.4 to 0.6 mm thick.
Thin skin Covers most of the body. Lacks a stratum lucidum. Has sweat glands, hair follicles and sebaceous glands. From 0.075 to 0.150 mm thick.
Coloring from Hemoglobin (pt. 1) An oxygen binding compound present in red blood cells. Bright red color upon binding oxygen. Gives blood vessels in dermis a reddish tint.
Coloring from Hemoglobin (pt. 2) Seen most easily in fair skinned individuals. More visible if blood vessels dilate.
Coloring from Melanin (pt. 1) Pigment produced and stored in melanocytes. Occurs in black, brown, tan, yellow-brown shades. Transferred to keratinocytes in stratum basale.
Coloring from Melanin (pt. 2) Amount in skin varies according to heredity and light exposure. UV light stimulating melanin production. All people born with the same number of melanocytes.
Coloring from Carotene (pt. 1) Yellow-orange pigment. Acquired from yellow-orange vegetables. Accumulates inside subcutaneous fat and keratinocytes of statum corneum.
Coloring from Carotene (pt. 2) Converted to vitamin A within the body. Plays important roles in - vision, reducing free radicals, immune function.
Nevus Commonly called a mole. Harmless overgrowth of melanin forming cells. Rarely may become malignant - should be monitored for changes suggesting malignancy.
Freckles Yellowish or brown spots. Represent localized areas of increased melanocyte activity. Degree of pigmentation based on sun exposure and heredity.
Hemangioma Skin discoloration due to benign blood vessel tumor
Capillary hemangiomas Appear in skin as bright red to deep purple nodules. Usually present at birth and disappear in childhood. Known as strawberry-colored birthmarks.
Cavernous hemangiomas Involve larger dermal blood vessels. May last a lifetime. Known as port-wine stains.
Ridge patterns (skin pt. 1) Small conical pegs in thin skin. Complex arches and whorls on finger, palms, soles and toes - called friction ridges.
Ridge patterns (skin pt. 2) Formed from large folds and valleys of dermis and epidermis. Help increase friction on contact. Each individual with a unique pattern of friction ridges. Allows for personal identification.
Dermis Deep to the epidermis. Ranges in thickness from 0.5mm to 3.0mm. Composed of connective tissue.
Components of dermis (pt. 1) Primarily collage with elastic and reticular fibers. Motile dendritic cells serving an immune function. Blood vessels, sweat glands, sebaceous glands.
Components of dermis (pt. 2) Hair follicles, nail roots, sensory nerve endings, arrector pili. Divided between the papillary layer and deeper reticular layer.
Papillary layer of dermis (pt. 1) Superficial region of the dermis. Directly adjacent to epidermis. Composed of areolar connective tissue.
Papillary layer of dermis (pt. 2) Derives name from projections of the dermis - dermal papillae. Contains capillaries and sensory nerve endings. Projections of epidermis interdigitating with papillae - epidermal ridges. Interlock and increase the area of contact between layers.
Reticular layer of the dermis Deeper, major portion of the dermis. Extends from papillary layer to subcutaneous layer. Consists primarily of dense irregular connective tissue. Contains large bundles of collagen fibers - fibers interwoven
Lines of cleavage a.k.a. Tension lines, bundles functioning to resist stress, important factor in surgery (incisions parallel to lines will heal quicker than those that are perpendicular)
Collagen fibers Provide tensile strength
Elastic fibers Provide stretch and recoil
Skin stretched beyond its capabilities Some collagen fibers can be torn. Stretch marks may develop (striae)
Flexibility and thickness of dermis Diminished by UV light and aging. May cause sagging or wrinkled skin.
Innervation and blood supply Dermis with extensive nerve fibers. Sensory nerve fibers detect pressure, vibration and cold. Motor nerve fibers control blood flow and gland secretions.
Dermal blood vessels Supply nutrients to epidermis and dermis. Large vessels along reticular and subcutaneous border. Smaller vessels branching into dermis and dermal papillae. Play an important role in body temperature and blood pressure regulation.
Vasoconstriction Blood vessel diameters narrowed. Blood shunted from periphery toward deeper structures. Occurring when trying to conserve heat. Look pale when exposed to cold.
Vasodilation Blood vessel diameter increased. More blood close to body surface. Occurs when needing to lose heat. Why people may become flushed during exercise.
Tattoos Permanent images produced on integument. Dye injected into dermis. Becomes permanent part of dermis layer. Usually impossible to completely remove.
Subcutaneous layer characteristics Not considered part of integument. Consists of areolar and adipose connective tissue. Termed subcutaneous fat in adipose areas. Connective tissue fibers interwoven with those of reticular dermis. Pads and protects.
Subcutaneous layer functions Acts an energy reservoir. Provides thermal insulation. Drugs often injected here.
Subcutaneous layer functions male/female Sexes with different layer thickness and distribution. Women are generally thicker - breasts, buttocks, hips and thighs. Men are generally thinner - neck, upper arms, abdomen, lower back, buttocks.
Epidermal derivatives Nail, hair, exocrine glands (from epidermal epithelium)
Nails Scalelike modifications of the stratum corneum. Form on the dorsal edges of fingers and toes. Protect the distal tips of the digits. Assit in grasping objects.
Lunula Whitish semi-lunar area on proximal end of nail body.
Lanugo Fine, unpigmented, downy hair. Appears in last trimester.
Vellus Fine hair. Primary human hair. Found on upper and lower limbs.
Terminal hair Coarser, pigmented, longer. On scalp, eyebrows, eyelashes, mens' beards. During puberty replaces vellus hair in axillary and pubic regions.
Hair follicle Oblique tube surrounding hair root.
Arrector pili Thin ribbons of smooth muscle. Elevates hair producing goosebumps.
Functions of hair - Protection Protects scalp from sunburn and injury. Hair within nostrils trapping particles. Hair within ears protecting from foreign matter. Eyelashes protecting eyes. Eyebrows keeping sweat out of eyes.
Functions of hair - Heat retention Prevents loss of heat from scalp to air.
Functions of hair - sensory, visual Sensory reception - has associated tactile receptors. Visual identification - Important in determining age, sex, specific individuals.
Functions of hair - chemical signal Disperse pheromones. Chemical signals involved in attracting sexual partners. Secreted by specific sweat glands onto hairs in axillary and pubic regions.
Hair color Results from synthesis of melanin in the matrix adjacent to hair papillae. Reflects genetic, environmental and hormonal factors. Becomes lighter with age as pigment production decreases.
Hair loss 10-100 hairs per day, may be a result of drugs, dietary factors, radiation, high fever, stress.
Alopecia Thinning of hair, usually a result of aging.
Diffuse hair loss Mostly in women. Hair shed from all parts of scalp.
Male pattern baldness Loss of hair from only some regions of scalp. Combination of genetic and hormonal factors. Baldness is dominant in males and recessive in females. Expressed only in the presence of high testosterone.
Exocrine glands Sweat, sebaceous
Sweat glands Two types - merocrine and apocrine. Sweat gland duct carries secretions. Opening of the gland duct on epidermal surface termed sweat pore. Discharge secretions in response to sympathetic stimulation.
Merocrine sweat glands (pt. 1) Most numerous. Discharge secretions known as sweat - 99% water and 1% chemicals (electrolytes, metabolites, waste products)
Merocrine sweat glands (pt. 2) Major function - thermoregulation. Provide a means for loss of water and electrolytes. Secretions diluting harmful chemicals. Secretions with antibacterial activity. Produce secretions by exocytosis.
Apocrine sweat glands (pt. 1) Discharge secretions onto hair follicles. Produce secretions by exocytosis. Found in axillae, nipples, in public and anal region.
Apocrine sweat glands (pt. 2) Produce viscous cloudy secretions - contain proteins and lipids. Produce odor when acted on by bacteria. Start producing secretions during puberty.
Sebaceous glands Produce oily secretion called sebum. Sebum acts as a lubricant for skin and hair, has bactericidal properties, discharged into hair follicle. Stimulated by hormones, especially androgens, activated during puberty.
Ceruminous glands Modified apocrine sweat glands. Secretions form waterproof earwax (cerumen).
Mammary glands Modified apocrine sweat glands of the breast. Only function in pregnant and lactating females is to produce milk.
Acne Plugged sebaceous ducts. Prevalent during teenage years. Treatments - benzoyl peroxide, salicylic acid, antibiotics, Vit. A like compounds
Regeneration Replacement of damaged cells with same cell type. Restores organ function.
Fibrosis Gap filled with scar tissue. Composed primarily of collagen produced by fibroblasts. Functional activities not restored. If organ too damaged or cells lack ability to divide.
Stages of wound healing 1) Blood vessel bleeds into wound 2) Clot forms and leukocytes clean wound. 3) Blood vessels regrow and granulation tissue forms. 4) Epithelium regenerates and connective tissue fibrosis occurs.
Degrees of burns First degree Involve epidermis only, slight redness and pain, immerse burned area in cold water.
Degrees of burns Second degree Involve epidermis and part of dermis. Skin blistered and painful. Slight scarring.
Degrees of burns Third degree Involve epidermis, dermis and subcutaneous layers. Requires hospitalization. Treatment for dehydration and infection. Require additional caloric intake. Severe scarring. May need debridement and skin graft from one part of body to another.
Degrees of burns Fourth degree Irreversible damage - death.
"Rule of Nines" Tool for estimating severity of burns
UV Radiation Radiation damaging DNA in epidermal cells. Accelerates aging. Predominant factor in skin cancer development.
Skin Cancer Most common type of cancer. Most commonly on the head and neck. Fair skinned individuals are at higher risk. Risk reduced with sunscreen use and avoiding UV overexposure. Periodic skin exams recommended.
Skin Cancer Check - A A - Asymmetrical
Skin Cancer Check - B B - Border Should not have blurred or jagged lines
Skin Cancer Check - C C - Color Should only be one color
Skin Cancer Check - D D - Diameter Should not be larger than a pencil eraser
Skin Cancer Check - E E - Elevation
Basal cell carcinoma Most common type of skin cancer but least dangerous. Originates in stratum basale. Usually on face, surgically removed.
Squamous cell carcinoma Originates in stratum spinosum. Usually found on scalp, ears, lower lip or dorsum of hand. May metastasize to other body parts. Surgically removed and early detection.
Malignant melanoma Most deadliest type of skin cancer due to growth and metastasis. Originates in melanocytes, usually in a pre-existing mole. Early detection, surgically removed. If in later stages, treated with chemotherapy, interferon therapy and radiation.
Created by: daydreamer67