Slides 1 to 51 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Components of the Integumentary System Figure 5-1

Integumentary Structure/Function Integumentary* System Components Cutaneous** membrane Epidermis – top layer (thinner) Dermis – below epidermis (thicker) Accessory structures Subcutaneous layer (hypodermis) * integumentary means “covering” * cutaneous means “skin” Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Main Functions of the Integument Protection / Waterproofing keratinized layer of dead cells white blood cells Temperature maintenance sweat glands capillaries Synthesis and storage of nutrients subcutaneous adipose tissue Sensory reception temp., touch, pain Excretion and secretion sweat oil / wax Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function The Epidermis Stratified squamous epithelium Several distinct cell layers Thick skin—five layers On palms and soles Thin skin—four layers On rest of body Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function The Structure of the Epidermis stratum = layer Figure 5-2

Integumentary Structure/Function Cell Layers of The Epidermis (from bottom up) Stratum germinativum = growing/dividing layer Stratum spinosum = spiny layer Stratum granulosum = grainy layer Stratum lucidum (in thick skin) = clear layer Stratum corneum = horny layer Dying superficial layer (topmost) accumulation of keratin (a tough, water resistant protein) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Cell Layers of The Epidermis Stratum germinativum Basal layer Stem cells Mitotic cell division layer Source of replacement cells melanocytes Synthesize melanin = brown pigment Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Cell Layers of the Epidermis Intermediate layers Stratum spinosum (spiny layer) Superficial to stratum germinativum Stratum granulosum (grainy layer) Keratin granules in cytoplasm No cell division Stratum lucidum (clear layer) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Cell Layers of the Epidermis Stratum corneum Most superficial layer Flattened (squamous) cells Dead cells Abundant keratin Keratinized (also, cornified) Tough, water-resistant protein Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Sources of Skin Color Melanocytes make pigment, melanin melanin provides UV protection gives reddish-brown to brown-black color Carotene a pro-vitamin (gets converted to vitamin A) contributes orange-yellow color provided from diet Hemoglobin red blood pigment carries O2 to tissues and some CO2 away from tissues The carotenes possess antioxidant properties. Vitamin A serves several biological functions including involvement in the synthesis of certain glycoproteins. Vitamin A deficiency leads to abnormal bone development, disorders of the reproductive system, xerophthalmia (a drying condition of the cornea of the eye), and ultimately death.

Integumentary Structure/Function Melanocytes Figure 5-3

Integumentary Structure/Function Effects of UV Radiation Beneficial effect Activates synthesis of vitamin D3 Harmful effects Sun burn Wrinkles, premature aging Malignant melanoma (bad) Basal cell carcinoma (not too bad) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Two Important Types of Skin Cancer Figure 5-4 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Key Note The epidermis is a multi-layered, flexible, self-repairing barrier that prevents fluid loss, provides protection from UV radiation, produces vitamin D3, and resists damage from abrasion, chemicals, and pathogens (=disease-causers) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Layers of the Dermis (from top down) Papillary layer Underlies epidermis Named for dermal papillae* Loose connective tissue Supports, nourishes epidermis Provides sensory nerves, lymphatics, and capillaries *papillae = “little fingers” Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Layers of the Dermis Reticular layer Tough, dense, fibrous layer collagen fibers limit stretch elastin fibers provide flexibility blends into papillary layer (above) blends into subcutaneous layer (below) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Other Dermal Components Epidermal accessory organs Cells of connective tissues proper Communication with other organ systems Cardiovascular Lymphatic Nervous Sensation Control of blood flow and secretion Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Key Note The dermis provides mechanical strength, flexibility, and protection for underlying tissues. It is highly vascular (lots of blood vessels) and contains a variety of sensory receptors that provide information about the external environment. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function The Subcutaneous Layer Composed of loose connective tissue Stabilizes skin position Loosely attached to dermis above Loosely attached to muscle below Contains many fat cells (adipose tiss.) Provides thermal insulation Cushions underlying muscle tissue. Safely receives hypodermic needles Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Hair Follicles The arrector pili muscles are what produce “goose bumps.” Figure 5-5(b)

Integumentary Structure/Function Accessory Structures Sebaceous glands (oil glands) Oily secretion Sebum Hair shaft lubricant Sebaceous follicle Skin lubricant Skin waterproofing Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function The Structure of Sebaceous Glands and Their Relationship to Hair Follicles Figure 5-6

Integumentary Structure/Function Sweat Glands Apocrine Odorous secretion (“funky”) Absent before puberty Present in axilla (=armpit), groin Merocrine Watery sweat (~1% NaCl) For heat loss Widely present in skin (up to 500/cm2) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Integumentary Structure/Function Sweat Glands Figure 5-7

Integumentary Structure/Function Key Note The skin plays a major role in controlling body temperature. It acts as a radiator, with the heat being delivered by the dermal circulation and removed primarily by the evaporation of sweat or perspiration. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Skin Injury and Repair Four Stages in Skin Healing Inflammation Blood flow increases Phagocytes attracted Scab formation Cell division and migration Scar formation Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response. Epidermis Dermis Figure 5-9 2 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Macrophages and fibroblasts Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response. After several hours, a scab has formed and cells of the stratum germinativum are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving with the enhanced circulation in the area. Clotting around the edges of the affected area partially isolates the region. Epidermis Scab Migratory epithelial cells Macrophages and fibroblasts Dermis Sweat gland Granulation tissue Figure 5-9 3 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Fibroblasts = connective tissue cells that secrete fibers. One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating. Fibroblasts Figure 5-9 4 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating. After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis. Scar tissue Fibroblasts Figure 5-9 5 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response. After several hours, a scab has formed and cells of the stratum germinativum are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving with the enhanced circulation in the area. Clotting around the edges of the affected area partially isolates the region. Epidermis Scab Migratory epithelial cells Macrophages and fibroblasts Dermis Sweat gland Granulation tissue One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating. After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis. Scar tissue Fibroblasts Figure 5-9 1 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Squamous cell carcinoma Melanoma Skin Cancer Basal cell carcinoma Squamous cell carcinoma Melanoma

Basal Cell Carcinoma Least malignant and most common skin cancer Stratum germinativum cells proliferate and invade the dermis and hypodermis Slow growing and do not often metastasize (spread around body) 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 Prognosis is good if treated by radiation therapy or removed surgically

Melanoma Cancer of melanocytes is the most dangerous type of skin cancer 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)

Melanoma Treated by wide surgical excision accompanied by immunotherapy Chance of survival is poor if the lesion is over 4 mm thick

Burns First-degree – only the epidermis is damaged Symptoms include localized redness, swelling, and pain Second-degree – the epidermis and upper regions of dermis damaged Symptoms mimic first degree burns, but blisters also appear Third-degree – involve entire thickness of the skin Burned area appears gray-white, cherry red, or black, and there is no initial edema nor pain (since nerve endings are destroyed)

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 Figure 5.9a