Chapter 06 Lecture Outline

Chapter 06 Lecture Outline
See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes.

6.0 Integumentary System Integumentary system
Covers body and consists of skin and accessary tissues (nails, hair, sweat glands, sebaceous glands) Integument = skin Cutaneous membrane Barrier to the outside world Visual indicator of our physiology and health Dermatology, study of skin

6.1 Composition and Functions of the Integument
Describe the five layers (strata) of the epidermis. Differentiate between thick skin and thin skin. Explain what causes differences in skin color. Characterize the two layers of the dermis. Explain the significance of cleavage lines. 6.1 Composition and Functions of the Integument Learning Objectives:

6.1 Composition and Functions of the Integument (continued)
Describe how dermal blood vessels function in temperature regulation. List the functions of the subcutaneous layer. Name ways in which the epidermis protects the body and prevents water loss. Describe the integument’s involvement in calcium and phosphorus utilization. 6.1 Composition and Functions of the Integument (continued) Learning Objectives:

6.1 Composition and Functions of the Integument (continued)
Describe the integument’s role in secretion and absorption. Identify the immune cells that reside in the integument, and describe their actions. Explain how skin helps cool the body or retain warmth. List the sensations detected by the skin’s sensory receptors. 6.1 Composition and Functions of the Integument (continued) Learning Objectives:

Body’s largest organ Composed of all tissues types functioning in concert Surface covered by an epithelium Underlying CT Provides strength and resilience Contains smooth muscle associated with hair follicles Nervous tissue Senses touch, pressure, temperature, and pain Protects internal body structures 7 to 8% of body weight Thickness depends on body location

Layers of the integument Epidermis Stratified squamous epithelium Dermis Deeper layer Primarily dense irregular connective tissue Deep to dermis Subcutaneous layer (hypodermis) Layer of alveolar and CT Not part of integumentary system

Layers of the Integument
Figure 6.1

6.1a Epidermis Epithelium of the integument Epidermis
Keratinized, stratified squamous epithelium Specific layers, or strata Layers from deep to superficial Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum 1st three layers composed of living keratinocytes Corneum and lucidum composed of dead cells

6.1a Epidermis Stratum basale Deepest epidermal layer
Stratum germinativum or basal layer Single layer of cuboidal to low columnar cells Attached to underlying basement membrane Separates epidermis dermis Three cell types Keratinocytes Melanocytes Tactile cells

6.1a Epidermis Stratum basale (continued) Keratinocytes
Most abundant cells in epidermis Found in all layers Large stem cells Divide to regenerate new cells Replace old cells shed at surface Named for synthesizing of keratin Protein that strengthens epidermis Called cytokeratins in epidermis Make skin almost waterproof

6.1a Epidermis Stratum basale (continued) Melanocytes
Scattered among keratinocytes Produce and store pigment (melanin) in response to ultraviolet light Transfer pigment granules (melanosomes) into keratinocytes Pigment accumulates around nucleus of keratinocytes Shield nuclear DNA from UV radiation Responsible for darker tones of skin

Stratum basale (continued) Tactile cells
6.1a Epidermis Stratum basale (continued) Tactile cells Merkel cells Few in number Scattered within stratum basale Sensitive to touch When compressed, release chemicals Stimulate sensory nerve endings

6.1a Epidermis Stratum spinosum
Several layers of polygonal keratinocytes Spiny layer Named for spiny appearance on microscopy Daughter cells from stratum basale pushed into this layer Begin to develop into specialized, non-dividing keratinocytes Some in deepest level still dividing cells Nondividing keratinocytes attached by intercellular junctions, desmosomes

Stratum spinosum (continued)
6.1a Epidermis Stratum spinosum (continued) Epidermal dendritic cells (Langerhans cells) Fourth cell type In stratum spinosum and stratum granulosum Initiate immune response Responsive to pathogens and epidermal cancer cells

6.1a Epidermis Stratum granulosum 3 to 5 layers of keratinocytes
Granular layer Superficial to stratum spinosum Process begins called keratinization Keratinocytes fill with keratin Causes nucleus and organelles to disintegrate Fully keratinized cell dead but structurally sound Process not complete until in more superficial layers

6.1a Epidermis Stratum lucidum 2 to 3 cell layers Translucent
Clear layer Superficial to stratum granulosum Found only on thick skin on palms and soles Cells filled with a translucent protein, eleidin Intermediate product in keratin maturation Helps protect from UV light

6.1a Epidermis Stratum corneum Hornlike layer Most superficial layer
What you see when you look at your skin 20 to 30 layers of dead, interlocking keratinized cells Cells are anucleate (without a nucleus) and tightly packed Cornified epithelium contains large amount of keratin

6.1a Epidermis Stratum corneum (continued) 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 Shed Stratum corneum has dry, thickened surface Unsuitable for microorganism growth Secretions help protect

Epidermal Strata Figure 6.2

6.1a Epidermis Variations in the epidermis Thick versus thin skin
Between different body regions Between individuals In thickness, color, and skin markings Thick versus thin skin Thick skin Palms of hands, soles of feet Occurs in all five layers of epidermal strata Houses sweat glands No hair follicles or sebaceous glands From 0.4 to 0.6 mm thick

Thick versus thin skin (continued)
6.1a Epidermis Thick versus thin skin (continued) Thin skin Covers most of body Lacks a stratum lucidum Sweat glands, hair follicles, and sebaceous glands From to mm thick

Thick Skin and Thin Skin
Figure 6.3

6.1a Epidermis Skin color Normal color from hemoglobin, melanin, carotene Hemoglobin Oxygen-binding protein in red blood cells Bright red color upon binding oxygen Gives blood vessels in dermis a reddish tint Seen most easily in fair skinned individuals More visible if blood vessels dilate

6.1a Epidermis Melanin Pigment produced and stored in melanocytes
In black, brown, tan, yellow-brown shades Transferred to keratinocytes in stratum basale Amount in skin varies According to heredity and light exposure UV light stimulates melanin production All people with same number of melanocytes Darker-skinned individuals produce more and darker colored melanin

Production of Melanin by Melanocytes
Figure 6.4

6.1a Epidermis Carotene Yellow-orange pigment
Acquired from yellow-orange vegetables Accumulates in Subcutaneous fat Keratinocytes of stratum corneum Converted to vitamin A by body Plays important role in Vision Reducing free radicals Immune function

6.1a Epidermis Albinism Inherited recessive condition
Enzyme for melanin nonfunctional Melanocytes unable to produce melanin Individuals have white hair, pale skin pink irises

6.1a Epidermis Skin markings Nevus Freckles Mole
Harmless localized overgrowth of melanocytes Rarely becomes 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

6.1a Epidermis Skin markings (continued) Hemangioma
Skin discoloration due to benign blood vessel tumor Capillary hemangiomas Bright red to deep purple nodules Usually present at birth and disappear in childhood Strawberry-colored birthmarks Cavernous hemangiomas Larger dermal blood vessels May last a lifetime Port-wine stains

6.1a Epidermis Skin markings (continued) Friction ridges
Small conical pegs in thin skin Complex arches and whorls on finger, palms, soles, and toes Large folds and valleys of dermis and epidermis Increase friction on contact Each individual with a unique pattern of friction ridges Personal identification

Friction Ridges of Thick Skin
Figure 6.5

Clinical View: UV Radiation, Sunscreens, and Sunless Tanners
Sun generates UVA, UVB, UVC radiation UVC rays absorbed and do not reach earth Sunscreens block UVA and UVB rays Protect skin if used correctly Need high enough SPF (sun protection factor) Sunless tanners create tanned skin without UV light exposure. No protection against UV rays

What did you learn? What are the layers of the epidermis, starting from the surface of the skin? Which type of skin lacks a stratum lucidum and is found covering most of the body? Describe the different types of cells found in each stratum of the epidermis? In which stratum are the keratinocytes alive?

6.1b Dermis Dermis Deep to epidermis Thickness, 0.5 mm to 3.0 mm
Composed of CT proper Collagen with elastic and reticular fibers Motile dendritic cells serve an immune function Blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings, arrector pili Two layers Papillary layer and deeper reticular layer

Papillary layer of the dermis
6.1b Dermis Papillary layer of the dermis Superficial region Deep to epidermis Areolar connective tissue Named for projections of dermis, dermal papillae Projections of epidermis interdigitate with papillae, epidermal ridges Interlock and increase area of contact between layers

Reticular layer of the dermis
6.1b Dermis Reticular layer of the dermis Deeper, major portion of dermis From papillary layer to subcutaneous layer Dense irregular connective tissue Large bundles of collagen fibers project Fibers interwoven into meshwork surrounding structures

Layers of the Dermis Figure 6.6

6.1b Dermis Lines of cleavage and stretch marks
Collagen and elastic fibers oriented in parallel bundles at specific locations Due to applied stress during routine movement Bundles function to resist stress Orientation indicated by lines of cleavage (tension lines) Important consideration for surgery Incisions parallel to cleavage line are more likely to heal quickly Incisions perpendicular to cleavage lines are more likely to open due to cut elastic fibers

6.1b Dermis Lines of cleavage and stretch marks (continued)
Fibers contribute to skin characteristics Collagen fibers impart tensile strength Elastic fibers allow stretch and recoil If skin stretched beyond its capabilities Some collagen fibers torn Stretch marks, striae Flexibility and thickness of dermis Diminished by UV light and aging Causes sagging or wrinkled skin

Lines of Cleavage Figure 6.7

Clinical View: Tattoos
Permanent images produced on integument Dye injected into dermis Permanent part of dermis layer Usually impossible to completely remove a tattoo Lasers used to break down pigments Newer inks are available that allow for removal

6.1c Subcutaneous Layer Subcutaneous layer
Hypodermis, superficial fascia Not part of integument Areolar and adipose CT Subcutaneous fat in areas of more adipose tissue CT fibers interwoven with fibers of reticular dermis Pads and protects body Acts as energy reservoir Provides thermal insulation

Subcutaneous layer (continued)
6.1c Subcutaneous Layer Subcutaneous layer (continued) Drug injection site Extensive vascular network promotes rapid absorption Sexes have different layer thickness and distribution Thicker in women Accumulates primarily in breasts, buttocks, hips, and thighs Thinner in men Accumulates primarily in neck, upper arms, abdomen, lower back, buttocks

Integument Layers and the Subcutaneous Layer (Table 6.1)

What did you learn? The dermal papillae are a part of what layer of the skin? Should a surgeon generally cut perpendicular or parallel to cleavage lines? What two types of tissue form the subcutaneous layer?

6.1d Functions of the Integument
Protection Physical barrier Protects body from injury and trauma Protects from harmful chemicals, toxins, microbes, temperature extremes Protects deeper tissue from solar radiation

Prevention of water loss/gain Epidermis is water resistant, not waterproof Water lost by sweat, transpiration Fluids penetrate through epidermis and evaporate in air Dehydration a danger with severe burns Water escapes without skin barrier Skin also prevents water gain Water resistance prevents absorption

Metabolic regulation Vitamin D3 (cholecalciferol Synthesized from a steroid precursor by keratinocytes Occurs upon UV exposure D3 released into blood and transported to liver Converted to another intermediate molecule (calcidiol) Transported to kidney and converted to calcitriol Active form of vitamin D Considered a hormone

Vitamin D (continued) Increases absorption of calcium and phosphate Role in regulating blood levels of calcium and phosphate 10 to 15 minutes of sunlight daily is adequate Other forms of metabolic regulation Skin converts some compounds to slightly different forms E.g., hydrocortisone applied to skin helps stop inflammation/itching

Secretion and absorption Secretion Waste products secreted onto skin surface during sweating Urea, salts, water Amounts adjustable Role in electrolyte homeostasis Sebum of sebaceous glands lubricates skin surface and hair Helps make integument water resistant

Secretion and absorption (continued) Absorption Skin absorbs certain chemicals and drugs Other materials blocked Selectively permeable Some materials pass through, others blocked Transdermal administration Some oil-soluble drugs delivered by adhesive patch Slowly penetrate epidermis, absorbed into blood vessels

Immune function Epidermal dendritic cells In stratum spinosum Initiate immune response against pathogens Attack cancer cells Temperature regulation Influenced by capillaries and sweat glands in dermis Dermal blood vessels play important role in body temperature/blood pressure

Temperature regulation (continued) Vasoconstriction Vessels narrow, less blood travels through Less blood passage in dermal vessels means deeper vessels must be used Shunting of blood away from periphery of body toward deeper structures Occurs when body tries to conserve heat Reason we look pale when cold

Temperature regulation (continued) Vasodilation Diameter of vessels increases, more blood travel through More blood can travel close to surface Results in reddish/pink skin, flushed face during exercise Sensory Reception Skin has extensive innervation Distribution of nerve fibers Monitor stimuli in dermis and epidermis Touch receptors detect stimuli Send input to brain

What did you learn? What is the active form of vitamin D?
Where is it synthesized?

6.2 Integumentary Structures Derived from Epidermis
Epidermal derivatives Nails Hair Exocrine glands Formed during embryonic development Portions of epidermis invaginated into the dermis Hair and nails composed of dead cells Exocrine glands composed of living cells

6.2 Integumentary Structures Derived from Epidermis
Describe the function of nails. List the main components of the nail. Describe the structure of a hair and a follicle. List the functions of hair. Differentiate between the two types of sweat glands. Describe the function of sebaceous glands. Name the two other modified integumentary glands. 6.2 Integumentary Structures Derived from Epidermis Learning Objectives:

6.2a Nails Structure of nails
Scalelike modifications of stratum corneum Dorsal edges of fingers and toes Protect distal tips of digits Assist in grasping objects Distal whitish free edge (no underlying capillaries) Pinkish nail body (underlying capillaries) Nail root (part embedded in skin) These three constitute nail plate Nail bed Layer of living epidermis covered by nail body

6.2a Nails Structure of nails (continued) Nail matrix Lunula
Actively growing part of nail at proximal end of nail body Lunula Whitish semilunar area on proximal end of nail body Nail folds Folds of skin overlapping nail Eponychium (cuticle) Narrow band of epidermis from margin of nail wall onto nail body Hyponychium Thickened stratum corneum over which free nail edge projects

Structure of a Fingernail
Figure 6.9

Clinical View: Nail Disorders
Nails are indicative of overall health Brittle nails are prone to vertical splitting and separation of nail plate layers Ingrown nails with edge of nail digging into skin Onchomycosis is a fungal infection Yellow nail syndrome occurs when growth and thickening slows Spoon nails outer surface of nail is concave Beau’s lines indicate temporary interference with nail growth Vertical ridging common and usually harmless

6.2b Hair Hair found almost everywhere on the body except
Hands and palmar surface of fingers Sides and soles of feet and toes Lips Portions of external genitalia Hair type and distribution Single hair, pilus, shaped like slender filament Keratinized cells Grows from hair follicles

6.2b Hair Hair type and distribution (continued) Three types of hair
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, and eyelashes, men’s beards During puberty, replaces vellus hair in axillary and pubic regions

6.2b Hair Hair structure and follicles 3 zones along length of a hair
Hair bulb Swelling at base where hair originates in dermis Surrounds hair papilla, composed of CT Only region containing living epithelial cells Root Zone of hair from bulb to skin surface Shaft Portion of hair beyond skin surface

6.2b Hair Hair components Hair matrix Medulla Cortex Cuticle
Structure at base of the hair bulb Epithelial cells divide here Produce new cells, gradually pushed toward surface Medulla Remnant of matrix Flexible, soft keratin Cortex Flattened cells closer to outer hair surface Relatively hard Cuticle Single cell layer around cortex

Hair components (continued)
6.2b Hair Hair components (continued) Hair follicle Oblique tube surrounding hair root Extends into dermis and sometimes subcutaneous layer Outer CT root sheath originating in dermis Inner epithelial tissue root sheath originating from epidermis Arrector pili Thin ribbons of smooth muscle Extend from hair follicle to dermal papillae Elevates hair with contraction, “goosebumps”

Hair Figure 6.10

6.2b Hair Functions of hair Protection Facial expression
Protects scalp from sunburn and injury Hair within nostrils traps particles Hair within ears protects from foreign matter Eyelashes protect eyes Eyebrows keep sweat out of eyes Facial expression Hairs of eyebrows enhance facial expression Heat retention Prevents loss of heat from scalp

6.2b Hair Functions of hair (continued) Sensory reception
Tactile receptors detect light touch Visual identification Helps identify age or sex, specific individuals Chemical signal dispersal Disperse pheromones Chemical signals involved in attracting sexual partners Secreted by specific sweat glands onto hairs in axillary and pubic regions

6.2b Hair Hair color Synthesis of melanin in matrix adjacent to hair papillae Variations reflect genetic, environmental, and hormonal factors Lightens with age as pigment production decreases Gray hair results from gradual reduction in melanin White hair occurs due to complete stoppage of melanin production

Hair growth and replacement
6.2b Hair Hair growth and replacement Three phases of hair growth cycle Anagen—active phase Catagen—brief regression period Telogen—resting phase

6.2b Hair Anagen phase Living cells in hair bulb rapidly growing, dividing, and transforming into hair. Longest phase, 18 months to 7 years, depending on genetics Each hair grows 1/3mm/day, or 0.5 to 1 cm per month Normally, 80–95% of follicles are in anagen phase

6.2b Hair Catagen phase Telogen phase Cell division ceases
Follicle undergoes involution Lasts 3 to 4 weeks Telogen phase Hair is shed Lasts 3 to 4 months Then, hair bulb cells begin to regrow Follicle reenters anagen phase

6.2b Hair Hair loss Normally 10 to 100 hairs lost per day
More than that could mean a health problem Temporary loss could be from drugs, dietary factors, radiation, high fever, stress Thinning of hair, alopecia Due to aging Diffuse hair loss Hair shed from all parts of scalp Primarily in women Due to hormones, drugs, iron deficiency

6.2b Hair Hair loss (continued) Hair growth Male pattern baldness
Loss of hair first from only crown region of scalp Combination of genetic and hormonal factors Baldness allele dominant in males and recessive in females Expressed only in presence of high testosterone Hair growth Hirsutism Excessive male pattern hairiness Typically on face, chest, back Excess androgens Caused by medical condition or medication

6.2c Exocrine Glands of the Skin
Skin houses many types of exocrine glands Two most common types Sweat glands Sebaceous glands

Sweat glands Two groups Merocrine Apocrine Coiled, tubular secretory portion in reticular dermis Sweat gland duct transports secretions to surface Gland duct opens on epidermal surface, sweat pore Myoepithelial cells Contract to squeeze gland Discharge secretions in response to sympathetic stimulation

Merocrine sweat glands Most numerous and widely distributed Simple, coiled tubular glands Discharge secretions onto skin surface Produce secretion by exocytosis Secrete sweat Composed of 99% water and 1% other chemicals Includes: electrolytes, metabolites, and waste products

Merocrine sweat glands (continued) Major function, thermoregulation Regulation of body temperature by fluid evaporation Secretions Provide a means for loss of water and electrolytes May help eliminate ingested drugs Dilute harmful chemicals Antibacterial/antifungal activity

Apocrine sweat glands Coiled, tubular glands Discharge secretions into hair follicles located axillae, around nipples, in pubic and anal region Produce secretion by exocytosis Produce viscous cloudy secretions Contain proteins and lipids Produce odor when acted on by bacteria Start producing secretions during puberty

Sebaceous glands Holocrine glands Produce oily secretion, sebum Lubricant for skin and hair Bactericidal Discharges into a hair follicle Secretion stimulated by hormones, especially androgens Activated during puberty

Other integumentary glands Ceruminous glands Modified apocrine sweat glands Located only in external ear canal Secretions of waterproof earwax, cerumen Traps foreign material Lubricates acoustic meatus and eardrum Mammary glands Modified apocrine sweat glands of breast Only function in pregnant and lactating females Produce milk

Exocrine Glands of the Skin
Figure 6.11a

Clinical View: Acne and Acne Treatments
Plugged sebaceous ducts Typically begins during puberty Increased activity gland secretions may block pores Treatments Benzoyl peroxide, salicylic acid, antibiotics, vitamin A–like compounds, systemic retinoinds May lead to scarring if untreated

What did you learn? What are the three components of the nail plate?
What are the three portions of a hair? What do sebaceous glands secrete? Where is this material secreted?

6.3 Repair and Regeneration of the Integumentary System
Distinguish between regeneration and fibrosis. Describe the process of wound healing. 6.3 Repair and Regeneration of the Integumentary System Learning Objectives:

Tissue is repaired in one of two ways: regeneration or fibrosis Regeneration Replacement of damaged or dead cells with same cell type Restores organ function Fibrosis Gap filled with scar tissue Collagen produced by fibroblasts Functional activities not restored

Stages of wound healing 1) Cut blood vessels bleed into wound Blood clot forms and leukocytes clean wound Clot is a temporary barrier for pathogens Blood vessels re-grow and granulation tissue forms Vascular CT initially forms in wound Epithelium regenerates and CT fibrosis occurs

Wound healing Dependent on extent of injury Longer time needed for wider and deeper surfaces With severe damage Less likely to return to original condition Hair follicles, exocrine glands, nerves, and arrector pili muscle cells not repaired

Stages in Wound Healing
Figure 6.12

Clinical View: Psoriasis
Chronic autoimmune skin disease Keratinocytes attacked by T-lymphocytes Causes rapid overgrowth of new skin cells Patches of whitish, scaly skin on epidermal surface Symptoms: severe itching, pain, skin cracking Treatments Corticosteroids, UV light therapy, medications that interfere with skin cell production

Clinical View: Burns Major cause of accidental death
Caused by heat, radiation, chemicals, sunlight, electrical shock Threat to life from fluid loss, infection, effects of burned tissue First degree burns Involve only epidermis Slight redness and pain Immerse burned area in cool water Second degree burns Involve epidermis and part of dermis Skin blistered and painful Slight scarring

Clinical View: Burns (continued)
Third-degree burns Involve epidermis, dermis, and subcutaneous layer Require hospitalization Treatment for dehydration and infection Require additional caloric intake Severe scarring May need debridement and skin graft Burn severity can be measured by rule of nines Estimates surface area of burns

Clinical View: Burns (continued)
Treatments for burns Manage fluid loss Relieve swelling Manage pain Remove dead tissue Control infection Increase calorie intake

What did you learn? What is the term for the process of scar tissue formation?

6.4 Development and Aging of the Integumentary System
Describe how integument develops from two germ layers. Explain the developmental origins of nails, hair, and glands. Explain changes to the skin with age. List factors that contribute to skin aging. 6.4 Development and Aging of the Integumentary System Learning Objectives:

6.4a Integument and Integumentary Derivatives Development
Development around week 7 Ectoderm forms a layer of squamous epithelium Becomes periderm and basal layer Basal layer forms all epidermal layers By week 21 Formation of stratum corneum and friction ridges Periderm eventually sloughed off Mixes with sebum to produce coating on fetus skin, vernix caseosa Development around week 11 Dermis is derived from mesoderm Mesoderm becomes mesenchyme

6.4a Integument and Integumentary Derivatives Development
By week 32 Fingernails/toenails form Between weeks 9 and 12 Hair follicles appear Pockets of cells, hair buds By week 20 Sweat and sebaceous glands appear on palms/soles; later in other regions

6.4b Aging of the Integument
Skin changes with aging Reduced number and activity of stem cells Skin repair processes slows Thin skin less likely to protect from trauma Fewer collagen fibers Elastic fibers lose elasticity Crease lines form (wrinkles) Immune response decreased due to fewer dendritic cells Hair follicles produce thinner hair or none at all

6.4b Aging of the Integument
Skin changes with aging (continued) UV radiation Damages DNA in epidermal cells Accelerates aging Predominant factor in skin cancer Skin cancer Most common type of cancer Typically on head and neck Fair-skinned individuals at highest risk Risk reduced with sunscreen and avoiding UV overexposure Periodic skin exams recommended

Clinical View: Botox and Wrinkles
Botox is a treatment for wrinkles caused by facial muscle expression Clostridium botulinum toxin Blocks nerve impulses to facial expression muscles Decreases or eliminates wrinkles Botox injected into specific facial muscles Temporary effect only Muscles regain function and procedure must be repeated

What did you learn? What two primary germ layers form the integument?
What are the origins of nails, hair, and glands? Explain how the skin ages and the factors that affect this aging?

Chapter 06 Lecture Outline

Similar presentations

Presentation on theme: "Chapter 06 Lecture Outline"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Chapter 06 Lecture Outline

Similar presentations

Presentation on theme: "Chapter 06 Lecture Outline"— Presentation transcript:

Similar presentations

About project

Feedback