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    Slide 1:Unit III INTEGUMENTARY SYSTEM

    Chapter 5, pp.149- 165 Biology 220 Anatomy & Physiology I E. Gorski/ E. Lathrop-Davis/ S. Kabrhel

    Slide 2:Functions

    Protection immunity (intact surface blocks entry of pathogens) Regulation of body temperature changes in blood flow through cutaneous blood vessels (increases when hot; decreases when cold) sudoriferous glands (sweat --> evaporative cooling)

    Slide 3:Functions

    Sensation nerve endings and receptors detect stimuli general sensations (touch, pressure, pain, temperature) Excretion of wastes (in sweat; minor role) Blood reservoir (8-10% of total body flow) Vitamin (Vit.) D synthesis

    Slide 4:Structure

    Cutaneous membrane consists of: Epidermis: outer epithelial layer, and Dermis: underlying connective tissue (CT) layer Fig. 5.3, p. 152

    Slide 5:Epidermis

    consists of keratinized stratified squamous epithelium (keratin: fibrous protein, protects against abrasion) protects against disease by providing intact barrier against entry of pathogens protects against water loss (glycolipid) epidermal derivatives: glands, hair, nails cells: keratinocytes melanocytes Merkel cells Langerhans cells

    Slide 6:Epidermis (cont)

    Four or five major layers (from bottom up) stratum basale stratum spinosum stratum granulosum stratum lucidum (only in thick skin) stratum corneum

    Slide 7:Epidermis (cont)

    Stratum basale (S. germinitivum) single layer at basement membrane mitotically active contains: keratinocytes melanocytes Merkel cells Fig. 5.2, p. 150 Merkel Cell melanocytes produce dark pigment (melanin) all humans appear to have same number of melanocytes; differences in skin color may be due to differences in synthesis activity (some produce more melanin than others) or in hydrolysis activity (research is unclear whether this occurs within keratinocytes) keratinocytes give rise to bulk of other layers Merkel cells are connected to underlying nerve endings --> function in touchmelanocytes produce dark pigment (melanin) all humans appear to have same number of melanocytes; differences in skin color may be due to differences in synthesis activity (some produce more melanin than others) or in hydrolysis activity (research is unclear whether this occurs within keratinocytes) keratinocytes give rise to bulk of other layers Merkel cells are connected to underlying nerve endings --> function in touch

    Slide 8:Stratum spinosum: 8-10 cell layers thick contains: keratinocytes keratin glycolipid Langerhans cells

    Epidermis (cont) Fig. 5.2, p. 150 Keratinocytes accumulate materials begin to produce and accumulate keratin, a protein important to lessening the effects of abrasion also begin to flatten due to keratin produce glycolipid that is released into extracellular space between keratinocytes combination of carbohydrate and lipid important to water proofing (preventing water loss) Langerhans cells are fixed macrophages that function in immunityKeratinocytes accumulate materials begin to produce and accumulate keratin, a protein important to lessening the effects of abrasion also begin to flatten due to keratin produce glycolipid that is released into extracellular space between keratinocytes combination of carbohydrate and lipid important to water proofing (preventing water loss) Langerhans cells are fixed macrophages that function in immunity

    Slide 9:Epidermis (cont)

    Stratum granulosum: 3-5 cell layers thick cells continue to flatten due to accumulation of keratin nuclei and organelles begin to degenerate continue to produce glycolipid that helps in waterproofing Fig. 5.2, p. 150 also produce glycolipid that is released into extracellular space between kertinocytes combination of carbohydrate and lipid important to water proofing (preventing water loss)also produce glycolipid that is released into extracellular space between kertinocytes combination of carbohydrate and lipid important to water proofing (preventing water loss)

    Slide 10:Epidermis (cont)

    Stratum lucidum: present only in thick skin on palms and soles consists of 3-4 layers of translucent cells (cell membranes not visible) Stratum lucidum

    Slide 11:Epidermis (cont)

    Stratum corneum: thick region of dead cells (25-30 cell layers) Fig. 5.2, p. 150 keratin and thickened plasma membranes protect against abrasion glycolipid between cells protects against water loss cells are too far from blood supply in underlying connective tissue so they are deadkeratin and thickened plasma membranes protect against abrasion glycolipid between cells protects against water loss cells are too far from blood supply in underlying connective tissue so they are dead

    *Epidermal derivatives

    Slide 12:Dermis

    2 major layers: Papillary region: areolar CT Meissners corpuscles dermal papillae Reticular region: dense irregular CT, adipose Pacinian corpuscles hair follicles* sebaceous (oil) glands* sudoriferous glands* Fig. 5.4, p. 157 Dermal papillae are upward extensions of the papillary region of the dermis Meissners corpuscles are touch receptors found in papillary region Pacinian corpuscles are located deep in the dermis or hypodermis and function in pressure reception Hair follicles, sebaceous glands and sudoriferous glands are epidermal derivatives they arise from the epidermis during fetal development and extend down into the dermisDermal papillae are upward extensions of the papillary region of the dermis Meissners corpuscles are touch receptors found in papillary region Pacinian corpuscles are located deep in the dermis or hypodermis and function in pressure reception Hair follicles, sebaceous glands and sudoriferous glands are epidermal derivatives they arise from the epidermis during fetal development and extend down into the dermis

    Slide 13:Hypodermis

    also called subcutaneous layer or superficial fascia not really part of skin consists of areolar CT and adipose tissue Pacinian corpuscles Fig. 5.4, p. 157 Pacinian corpuscles - pressure receptors found deep in reticular region of dermis or in hypodermisPacinian corpuscles - pressure receptors found deep in reticular region of dermis or in hypodermis

    Slide 14:Skin Color and Tanning

    Color is due to pigments melanin yellow to black carotene yellow hemoglobin reddish cyanosis bluish color due to lack of oxygen Defects albinism no melanin anywhere vitiligo little or no melanin in certain areas melanin yellow to dark-brown pigment skin color varies from yellow (e.g., in many Asian people) to reddish-brown to black (e.g., many African-Americans) depending on amount and type of melanin carotene orange-yellow pigment found in certain plant foods; accumulates in epidermis and hypodermis (not made in skin); especially noticible in Caucasians hemoglobin - from underlying blood vessels cyanosis results when blood is under-oxygenated and skin appears bluish; normally only seen in European-Americans and others with light skin Defects: Albinism - no pigment made (genetic defect in which melanocytes do not make melanin throughout body); eyes appear red and are very sensitive to light Vitiligo - partial or complete loss of melanocytes from selected areas of body surrounded by normally-pigmented skin/hairmelanin yellow to dark-brown pigment skin color varies from yellow (e.g., in many Asian people) to reddish-brown to black (e.g., many African-Americans) depending on amount and type of melanin carotene orange-yellow pigment found in certain plant foods; accumulates in epidermis and hypodermis (not made in skin); especially noticible in Caucasians hemoglobin - from underlying blood vessels cyanosis results when blood is under-oxygenated and skin appears bluish; normally only seen in European-Americans and others with light skin Defects: Albinism - no pigment made (genetic defect in which melanocytes do not make melanin throughout body); eyes appear red and are very sensitive to light Vitiligo - partial or complete loss of melanocytes from selected areas of body surrounded by normally-pigmented skin/hair

    Slide 15:Skin Color and Tanning

    Tanning caused by exposure to UV radiation increased production of melanin by melanocytes and spreading of melanin to keratinocytes Evolution of skin color strong correlation between skin color and strength of sunlight across the globe people who live in the north evolved fair skin ?absorb more UV light for adequate production of vitamin D people in the tropics evolved dark skin to block out sun and protect their folate reserves UV light cuts folate levels in skin (folate is crucial for CNS development) melanin evolved to absorb or disperse UV light use of tanning salons has been tied to spina bifida in at least 3 cases Discover Magazine article http://www.discover.com/recent_issue/index.html original article: The evolution of human skin coloration Nina G. Jablonski, George Chaplin Journal of Human Evolution, Vol. 39, No. 1, Jul 2000, pp. 57-106 (doi:10.1006/jhev.2000.0403) use of tanning salons has been tied to spina bifida in at least 3 cases Discover Magazine article http://www.discover.com/recent_issue/index.html original article: The evolution of human skin coloration Nina G. Jablonski, George Chaplin Journal of Human Evolution, Vol. 39, No. 1, Jul 2000, pp. 57-106 (doi:10.1006/jhev.2000.0403)

    Slide 16:Epidermal Derivatives: Hair (Pili)

    keratinized cells originating in follicle bulb root hair plexus arrector pili muscle shaft root Fig. 5.3, p. 152 http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab15/EXAMPLES/Exarrpil.htm follicle is epithelial; extends into dermis bulb is deep, expanded part of follicle responsible for formation of new hair root hair plexus is nerve endings around bulb arrector pili muscle (smooth muscle) pulls on the bulb when stimulated by sympathetic innervation (cold or fear) makes hair stand upright causes dimpling of skin --> goose bumps hair shaft - appears above skin hair root - lies within skinfollicle is epithelial; extends into dermis bulb is deep, expanded part of follicle responsible for formation of new hair root hair plexus is nerve endings around bulb arrector pili muscle (smooth muscle) pulls on the bulb when stimulated by sympathetic innervation (cold or fear) makes hair stand upright causes dimpling of skin --> goose bumps hair shaft - appears above skin hair root - lies within skin

    Slide 17:Hair Types and Growth

    Types vellus terminal Stimulation of growth terminal hairs stimulated by presence of androgens Disorders of hair growth and replacement hirsutism alopecia male pattern baldness Minoxidil (antihypertensive ) Types Vellus hairs - soft, overall body hair some convert to terminal hairs after puberty Terminal hairs - coarse, long hair of eyebrows, scalp, beard, pubic and axillary regions; grow in response to androgens Stimulation of growth of terminal hair is normally cyclic Disorders of hair growth and replacement hirsutism = excess hair growth due to presence of increased androgens in women (adrenal or ovarian tumor) alopecia = thinning of hair, usually due to age but also influenced by diet; hairs are not replaced as fast as they are normally lost or are lost more rapidly than normal male pattern baldness = genetic loss of hair due to programmed response of scalp hairs to testosterone; sex-linked characteristic minoxidil (antihypertensive - i.e., used to treat high blood pressure) - stimulates hair regrowthTypes Vellus hairs - soft, overall body hair some convert to terminal hairs after puberty Terminal hairs - coarse, long hair of eyebrows, scalp, beard, pubic and axillary regions; grow in response to androgens Stimulation of growth of terminal hair is normally cyclic Disorders of hair growth and replacement hirsutism = excess hair growth due to presence of increased androgens in women (adrenal or ovarian tumor) alopecia = thinning of hair, usually due to age but also influenced by diet; hairs are not replaced as fast as they are normally lost or are lost more rapidly than normal male pattern baldness = genetic loss of hair due to programmed response of scalp hairs to testosterone; sex-linked characteristic minoxidil (antihypertensive - i.e., used to treat high blood pressure) - stimulates hair regrowth

    Slide 18:Hair Color

    Primarily due to melanin presence of sulfur (blonde) or iron (red) Gray/white hair lack of pigment (melanin) presence of air bubbles in the medulla (core) of hair shaft Normal color: Melanin comes in slightly different versions - yellow to dark-brown to black Red hair also has iron-containing pigment Blonde hair may also have sulfur present Gray/white hair - melanocytes decrease production of melanin with age --> hair then lacks pigment and appears gray or whiteNormal color: Melanin comes in slightly different versions - yellow to dark-brown to black Red hair also has iron-containing pigment Blonde hair may also have sulfur present Gray/white hair - melanocytes decrease production of melanin with age --> hair then lacks pigment and appears gray or white

    Slide 19:Epidermal Derivatives: Nails

    Nails protect dorsal surfaces of digits keratin-filled cells nail matrix (proximal portion of nail bed) Nail matrix Free edge Fig. 5.7, p. 161 Hard surface composed of keratinized cells Nail matrix produces new cells which are pushed out over nail bed cells eventually extend past nail bed as free edgeHard surface composed of keratinized cells Nail matrix produces new cells which are pushed out over nail bed cells eventually extend past nail bed as free edge

    Slide 20:Epidermal Derivatives

    Sebaceous Glands secrete sebum lubricates and protects hair has bactericidal activity (kills bacteria) found everywhere except palms and soles whiteheads blackheads acne Sebum is oily (lipid) substance whiteheads occur when oil accumulates blackheads occur when whitehead material becomes oxidized acne occurs when sebaceous glands become inflamed, usually from bacterial infectionSebum is oily (lipid) substance whiteheads occur when oil accumulates blackheads occur when whitehead material becomes oxidized acne occurs when sebaceous glands become inflamed, usually from bacterial infection

    Slide 21:Epidermal Derivatives

    Sudoriferous Glands = sweat glands found in all regions except nipples and parts of external genitalia eccrine sweat glands apocrine sweat glands ceruminous glands mammary glands http://www.georgetown.edu/dml/educ/hist/lab16/31.htm eccrine sweat glands: secrete sweat for temperature regulation and excretion; sweat is 99% water with some salts, metabolic wastes (e.g., urea), lactic acid (attracts mosquitos) apocrine sweat glands: begin to function at puberty; axilla and pubic regions; products include protein and fatty substances in addition to watery sweat (breakdown by bacteria leads to foul odors); originally thought to secrete as apocrine glands, now known to have merocrine function (but name never changed) ceruminous glands: modified glands (secrete wax) in ears mammary glands: secrete milk (in lactating mother)eccrine sweat glands: secrete sweat for temperature regulation and excretion; sweat is 99% water with some salts, metabolic wastes (e.g., urea), lactic acid (attracts mosquitos) apocrine sweat glands: begin to function at puberty; axilla and pubic regions; products include protein and fatty substances in addition to watery sweat (breakdown by bacteria leads to foul odors); originally thought to secrete as apocrine glands, now known to have merocrine function (but name never changed) ceruminous glands: modified glands (secrete wax) in ears mammary glands: secrete milk (in lactating mother)

    Pages 164-165

    Slide 22:Burns

    damage inflicted by intense heat, electricity, radiation, or certain chemicals, all of which denature cell proteins and cause cell death severity depends on extent (Rule of Nines - see p. 165) degree (depends on which layer(s) of skin are involved) complications result from dehydration, electrolyte and protein imbalance, infections, renal shot down

    Slide 23:Burns (cont)

    First degree burn (partial thickness) - epidermis only painful second degree burn (partial thickness) - epidermis and upper region of dermis painful blistering occurs (separation of epidermis from dermis with fluid accumulation between) third degree burn (full thickness) - epidermis and all of dermis; may involve hypodermis little or no initial pain in immediate area (receptors and upper and distal portion of neurons damaged) may appear very red, ashen, or charcoal coloredFirst degree burn (partial thickness) - epidermis only painful second degree burn (partial thickness) - epidermis and upper region of dermis painful blistering occurs (separation of epidermis from dermis with fluid accumulation between) third degree burn (full thickness) - epidermis and all of dermis; may involve hypodermis little or no initial pain in immediate area (receptors and upper and distal portion of neurons damaged) may appear very red, ashen, or charcoal colored

    Slide 24:Tissue Repair (e.g., skin repair)

    Epithelial tissues usually repair well (regenerate) Connective tissues are often replaced by fibrous connective tissue (fibrosis) Events of tissue repair inflammation restoration of blood supply regeneration / fibrosis If epithelium is all thats injured, would usually heals fairly quickly by replacemnent of damaged cells with new ones If underlying connective tissue is damaged, fibrosis is more likely to occur Fibrosis is proliferation of fibrous connective tissue --> scarring events: inflammation - increases capillary permeability to bring white blood cells to area (helps destroy pathogens) restoration of any blood vessels that were damaged regeneration of epithelial tissue formation of replacement connective tissueIf epithelium is all thats injured, would usually heals fairly quickly by replacemnent of damaged cells with new ones If underlying connective tissue is damaged, fibrosis is more likely to occur Fibrosis is proliferation of fibrous connective tissue --> scarring events: inflammation - increases capillary permeability to bring white blood cells to area (helps destroy pathogens) restoration of any blood vessels that were damaged regeneration of epithelial tissue formation of replacement connective tissue

    Slide 25:Tissue Repair (cont)

    Fig. 4.12, p. 141

    Slide 26:Glands

    Endocrine glands: secrete products into blood (by way of interstitial fluid) Exocrine glands: Secrete products into ducts distinguished by shape and complexity distinguished by how they secrete merocrine glands holocrine glands Fig. 4.5, p. 124 merocrine glands release watery secretion via secretory vesicles e.g., most digestive glands, eccrine sudoriferous glands holocrine glands release products within cell fragments as cell comes apart e.g., sebaceous glands (only true example, p. 124, Marieb 5th ed.)merocrine glands release watery secretion via secretory vesicles e.g., most digestive glands, eccrine sudoriferous glands holocrine glands release products within cell fragments as cell comes apart e.g., sebaceous glands (only true example, p. 124, Marieb 5th ed.)