The Northern Red Salamander He has no lungs!

Skin Integumentary System Skin Derivatives Sweat glands Sebaceous glands Hair Nails

Integumentary System Functions Pathogens UV radiation Dehydration Protection Injury Production of vitamin D Sensation of T° and touch Regulation of body T°

Stratified squamous epithelium Skin Areolar CT + Dense Irregular CT Epidermis Skin Dermis Areolar CT + Dense Irregular CT

Deep to the dermis Hypodermis a.k.a. Superficial fascia Anchors, insulates , energy storage

Epidermis Stratified squamous epithelium Protection! Most of the cells = keratinocytes Cells that contain keratin Fibrous, waterproof protein

Epidermal dendritic cells Other epidermal cells Tactile cells Melanocytes

Melanocytes Produce the pigment melanin Transferred to the keratinocytes and protects their DNA from UV radiation

Epidermal dendritic cells (Langerhans cells) Engulf and destroy pathogens Travel to lymph nodes to present pathogen fragments to WBCs Mount an immune response

Tactile cells Light touch (Merkel cells) Associated with a nerve ending Tactilecell Sensory nerve ending

Thick skin 2 Basic Types of Skin Thin skin soles/palms 5 thick layers everywhere else 4 thin layers

5 Layers of Thick Skin Thin skin lacks the stratum lucidum Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Dermis Thin skin lacks the stratum lucidum (b)

Stratum Basale Basal most Superficial to dermis Single layer Mitotic cells Epidermal dendritic cells Tactile cells

Stratum Spinosum Several layers Cells linked by desmosomes Mitotic cells Epidermal dendritic cells Melanocytes

Stratum Granulosum Several layers Cells becoming keratinized Cells have visible granules

Stratum Lucidum Several layers Thick skin only Eleiden

Stratum Corneum Several layers Cells are dead bags of keratin Constantly shedding Strong

Dermis 2 Major Layers: 1. Papillary dermis 2. Reticular dermis

Papillary Dermis Upper ⅕ Areolar CT Vascular Upward projections called dermal papillae Anchored to epidermal ridges

Body T° Regulation Abundant blood vessels Allows heat to be delivered to skin surface

Reticular Dermis Upper ⅘ Dense Irregular CT Structural integrity

Epithelial derivatives Skin Appendages Sweat glands Sebaceous glands Hair Nails Epithelial derivatives

Merocrine sweat glands Types of Sweat Glands Apocrine sweat glands

Merocrine Sweat Glands 3,000,000 Exocrine Coiled tube + duct Water + ions, wastes, antibodies Evaporative cooling

Apocrine Sweat Glands Found in the axillae, pubic region, anal region. Exocrine Coiled tube + duct that empties into a hair follicle Sweat contains lipids and proteins

Ceruminous Glands Modified sweat glands External ear canal Cerumen Bactericide Fungicide Insect repellant

Sebaceous Glands Exocrine Branch from hair follicles Sebum Moisturizing Absences Bactericide

Hair Head (We’re bipeds!) Axillae & Pubic region Hair bulb Shaft Hair bulb Hair papilla Shaft + root Follicle Cuticle Medulla Cortex Arrector pili muscle Sensation Hair follicle Connective tissue root sheath Epithelial tissue root sheath Root Matrix Hair bulb Hair papilla (a)

Arrector Pili Muscle Vestigial Piloerection

More on Hair Functions of hair include: Helping to maintain warmth Alerting the body to presence of insects on skin Guarding the scalp against physical trauma, heat loss, and sunlight Hair is distributed over entire skin surface except Palms, soles, and lips Nipples and portions of the external genitalia Types of Hair Vellus – pale, fine body hair found in children and the adult female Terminal – coarse, long hair of eyebrows, scalp, axillary, & pubic regions Hair Thinning and Baldness Alopecia – hair thinning in both sexes True, or frank, baldness Genetically determined and sex-influenced condition Male pattern baldness – caused by follicular response to DHT (dihydrotestosterone)

Most skin tumors are benign and do not metastasize Skin Cancer Most skin tumors are benign and do not metastasize Crucial risk factor for nonmelanoma skin cancers is disabling of the p53 gene The three major types of skin cancer are: Basal cell carcinoma Least malignant and most common skin cancer Stratum basale cells proliferate and invade dermis and hypodermis Slow growing and do not often metastasize Can be cured by surgical excision in 99% of the cases Squamous cell carcinoma Arises from keratinocytes of stratum spinosum Arise most often on scalp, ears, and lower lip Grows rapidly and metastasizes if not removed Treated by radiation therapy or removed surgically Melanoma (next page)

Melanoma Melanomas have the following characteristics (ABCD rule) Melanoma - Cancer of melanocytes is the most dangerous type of skin cancer because it is: Highly metastatic Resistant to chemotherapy Melanomas have the following characteristics (ABCD rule) A: Asymmetry; the two sides of the pigmented area do not match B: Border is irregular and exhibits indentations C: Color (pigmented area) is black, brown, tan, and sometimes red or blue D: Diameter is larger than 6 mm (size of a pencil eraser) Treated by wide surgical excision accompanied by immunotherapy Chance of survival is poor if the lesion is over 4 mm thick

Burns Rule of Nines - Estimates the severity of burns First-degree – only the epidermis is damaged Symptoms include localized redness, swelling, and pain Second-degree – epidermis and upper regions of dermis are damaged Symptoms mimic first degree burns, but blisters also appear Third-degree – entire thickness of the skin is damaged Burned area appears gray-white, cherry red, or black; there is no initial edema or pain Rule of Nines - Estimates the severity of burns Burns considered critical if: Over 25% of the body has second-degree burns Over 10% of the body has third-degree burns There are third-degree burns on face, hands, or feet Lund and Browder

Developmental Aspects of the Integument Fetal Epidermis develops from ectoderm Dermis and hypodermis develop from mesoderm Lanugo – downy coat of delicate hairs covering the fetus Vernix caseosa – substance produced by sebaceous glands that protects the skin of the fetus in the amnion Adolescent to Adult Skin and hair become oilier and acne may appear Skin shows effects of cumulative environmental assaults around age 30 Scaling and dermatitis become more common Old Age Epidermal replacement of cells slows and skin becomes thinner Skin becomes dry and itchy Subcutaneous fat layer diminishes, leading to intolerance of cold Decreased elasticity and loss of subcutaneous tissue leads to wrinkles Decreased numbers of melanocytes and Langerhans’ cells increase the risk of skin cancer

Homeostatic Imbalances of the Skin Stretch marks, blisters, calluses, bed sores (Decubitus Ulcers) Erythema, pallor, jaundice, cyanosis, black and blue marks Acne Vulgaris most common skin disorder sebum and epithelial cells clog glands produces whiteheads and blackheads (comedones) anaerobic bacteria trigger inflammation (pimple) largely hormonally induced androgens stimulate sebum production treatments include antibiotics, topical creams, birth control pills Terms - intradermal injection; hypodermic (subcutaneous injection; intramuscular injection)