Do Now You heard about this new sanitizer that is supposed to not only kill off the germs, but also provides moisture. However, when you tried it out you experience an allergic reaction and develop a rash. What system is the rash affecting? What is purpose of this system? What components make up this system and which component is the rash on?

Integumentary System Chapter 6

Objectives To explain the function of the integumentary system Identify the components of the epidermis Identify and list the strata of the epidermis

Video! https://www.youtube.com/watch?v=Orumw-PyNjw

Integumentary System: Functions Protect underlying tissues from: infection Exposure dehydration Maintain normal body temperature Sensory detection Restricts water loss from deep tissues Excretes small amounts of waste Creates various biochemicals Integumentary System: Functions

Components Cutaneous membrane Accessory Structures Subcutaneous Layer Epidermis: superficial epithelium, contains stratified squamous ET Dermis: inner layer, contains CT, glands, smooth muscle, and blood Accessory Structures Hair Nails Exocrine Glands Subcutaneous Layer Beneath the skin Loose CT Adipose

The Epidermis

Epidermis: Characteristics Stratified squamous ET Composed of layers of keratinocytes (produce keratin) to help reduce water loss Avascular (no blood vessels) Deepest layer is nourished by blood vessels from dermis. Further away cells are from this layer, the less nutrient supply = cell death (Keratinization)

Layers of the Epidermis Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale/germinativum Superficial Deep

Layers of the Epidermis Continued Corneum 15-30 layers of dead keratinocytes Exposed to the surface, shed every 2 weeks Lucidum Thick skin only Appears clear Granulosum Grainy layer Stops dividing and starts producing keratin (Cells begin to die) Spinosum Spiny layer Cells flatten as pushed to surface Basale/ Germinativum Single layer Basal cells (stem) constantly reproducing/dividing

Thick vs. Thin Skin Epidermis consists of layers (strata): Thin Skin: 4 Layers Usually Hairy( Has hair follicles) No Stratum Lucidum Thick Skin: 5 Layers No Hair Located in areas subject to pressure or friction Ex: Palms of hands and soles of feet

Skin Color Melanocytes: specialized cells found in stratum basale that produce melanin Dark pigment that provides skin colo Absorbs UV radiation Depends on: Blood supply: blood pigment (hemoglobin) is red Cyanosis: low oxygen concentration, skin appears bluish Physiological Factors: Ex: diets high in yellow vegetables= orange/yellow skin (carotene) Melanin production UV exposure

Epidermal Cells Respond to epidermal growth factor (protein) Division Repair Secretion Synthesize vitamin D3 when exposed to UV Too much exposure= damage (DNA mutation) Can lead too: Wrinkles (altered fibroblasts) Cancers (altered epidermal cells and melanocytes)

Skin Cancer Cutaneous Carcinomas: Skin cancer originating from epithelial cells Squamous cell or basal cell carcinoma Most common Regular Exposure to sunlight Slow growing, usually cured by surgery or radiation Cutaneous Melanomas: Skin cancer originating from melanocytes Pigmented with melanin Caused by short, intermittent exposure to high intensity sunlight May be cured with surgery if caught early

Videos! https://www.youtube.com/watch?v=_4jgUcxMezM https://www.youtube.com/watch?v=0bQbmhbuRK8

The Dermis

Dermis: Characteristics Located between epidermis and subcutaneous layer Dense CT Vascular (blood vessels present) “feeds” itself and epidermis above Anchors accessory structures Hair follicles, sweat glands, blood vessels, nerves, sensory receptors Two layers: Papillary Layer (Superficial Layer) Reticular Layer (Deep Layer)

Dermis: Layers Papillary Layer Reticular Layer Thin Areolar CT Dermal Papillae help form fingerprints Feeds Epidermis (Contains blood vessels, lymphatics, and sensory nerves) Reticular Layer Thick Dense Irregular CT Provides Strength and Flexibility

Dermal Components

Stretch Marks Excessive stretching of the dermis Collagen and Elastin Fibers form lines of cleavage

Subcutaneous Layer (Hypodermis) Areolar CT and Adipose (not part of skin) Stabilizes skin’s position against underlying organs and tissues Shock absorber and insulator Few capillaries and no vital organs Vascular for quick absorption Safe for subcutaneous injections Useful for administering drugs

Cellulite Persistent/herniation of subcutaneous fat Causes dimpling of the skin (orange peel syndrome) May affect up to 90% of women at some point Causes: Hormones Genes Diet Lifestyle Factors Clothing

Accessory Structures Hair Sebaceous (oil) glands Sweat Glands Nails

Hair Human body has roughly 2.5 million hairs (75% on body) Everywhere except palms, soles, and lips Composed of keratinized dead cells produced in hair follicle Project deep into dermis, and often into the hypodermis

Hair Structure Hair papilla CT that contains capillaries and nerves Root Anchors hair into skin Shaft Pokes through epidermis (what you see) Has three layers: Cuticle- outermost layer, shiny surface Cortex- middle layer, contains pigments Contains a lot of sulfur=bad smell when hair burns Medulla- core of hair

Hair Follicle

Locations and Functions of Hair Head Protection from UV light Cushion a light blow to head Insulation Nostrils, ears, and eyes Prevent entry of particles Sensory Sensory nerve fiber at the base of every hair

Hair Color Produced by melanocytes at the hair papilla Range from yellow (little melanin) to black (mostly melanin) Red hair is a red type of melanin called pheomelanin When you age, melanin production declines Gray or white hair = no melanin

White streak “Poliosis”: the melanocytes, structures that make melanin and color the hair, shut down and the hair grows without pigment

Going Bald? Causes of hair loss: Not precisely known but is a mixture of the following: Genetics Presence of DHT (dihydrotestosterone) Medical conditions Certain medications

Other Structures Sebaceous glands Arrector Pili Muscle Secrete Sebum (oil) into hair follicle Helps keep hair and skin soft, pliable, and waterproof Inhibit bacterial growth Acne: inflammation of glands Arrector Pili Muscle Smooth muscle cells attached to hair follicle Muscle contracts → hair stands on end Very cold or emotional states: goose bumps!