Skin Structure and Growth Cosmetology: Skin Structure and Growth Milady’s Standard Cosmetology LEARNING MOTIVATION (WHY?) With the arrival of the 20th century came the scientific study of the hair, skin, and nails. It was the result of the molecule by molecule breakdown of DNA by high-powered microscopes that made it possible to complete the scientific study of proteins found in the hair, skin, and nails. While the level of knowledge needed by scientists is not necessary for cosmetologists, a thorough knowledge of the underlying structures of the skin, nails, and hair will benefit you in your role. Such knowledge will help you achieve the best possible results when providing hair, skin, and nail care services while at the same time providing the utmost protection for your client. Thoroughly analyzing the functions and components of the skin is the best way to understand how the skin works. With proper care, the skin can stay young and radiant looking for many years. This lesson contains extensive new terminology, which may seem overwhelming at first. We will cover the material in detail and introduce several exercises and activities that can be used to help you remember the terminology and definitions. The skin is the largest and one of the most important organs of the body. A healthy skin is slightly moist, soft, and flexible. It possesses a slightly acid reaction and is free from any disease or disorder. The ideal feel and appearance of skin is smooth and fine grained. That feel and appearance is known as skin texture. Hair, nails, and sweat and oil glands, all very important to the cosmetologist, are considered appendages of the skin. It is important to note that the skin on the eyelids is the thinnest of the entire body while the skin on the palms and soles of the feet is the thickest. Continued pressure on any part of the skin will result in calluses. The skin on the scalp has larger and deeper follicles to accommodate the longer hair found on the head.

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Objectives Describe the structure and composition of the skin. List the functions of the skin.

Anatomy of the Skin Dermatology Dermatologist Esthetician • DERMATOLOGY: The medical branch of science that deals with the study of the skin and its nature, structure, functions, diseases, and treatment. • DERMATOLOGIST: A physician engaged in the practice of dermatology. • ESTHETICIAN: A specialist in the cleansing, preservation of health, and beautification of the skin and body.

Histology of the Skin Largest organ of the body One of the most important body organs HISTOLOGY OF THE SKIN: The skin is the largest and one of the most important organs of the body.

Skin Specifics The skin of a typical 150 lb. man would: Cover 2 square yards Weigh about 9 pounds Skin protects muscles, bones, nerves Skin is a barrier against environment Eyelids have thinnest skin Soles of feet are thickest Continued pressure causes callus

Healthy Skin Slightly moist Soft and flexible Smooth and fine-grained texture Possesses slightly acid reaction

Appendages of the Skin Hair Nails Sweat and oil glands

Two Divisions of Skin Dermis Epidermis

Epidermis Stratum germinativum Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum EPIDERMIS: Outermost layer, commonly called cuticle or scarf skin. Thinnest layer of skin forms protective covering; contains no blood vessels; has nerve endings. • Stratum germinativum. The basal cell layer, formerly known as stratum mucosum, is deepest layer responsible for growth of epidermis; contains pigment, called melanin, also found in hair. Pigment protects skin cells from destructive effects of excessive ultraviolet rays by means of cells called melanocytes, which produce the melanin. • Stratum spinosum. The spiny layer is found just above the basal cell layer. • Stratum granulosum. Granular layer consisting of cells that look like granules. Cells are almost dead and are pushed to surface to replace those that are shed from stratum corneum. • Stratus lucidum. Clear layer consisting of small, transparent cells through which light can pass. • Stratum corneum. Horny (outer) layer. Its scale-like cells are constantly shed and replaced. Cells contain protein keratin, which combines with a thin covering of oil making the skin almost waterproof.

Dermis Papillary layer Reticular layer Subcutaneous tissue DERMIS: Underlying or inner layer of skin. Also called derma, corium, cutis, or true skin. About 25 times thicker than epidermis. Highly sensitive; contains blood vessels, lymph vessels, nerves, sweat and oil glands, hair follicles, arrector pili muscles, and papillae. Made up of two layers: the papillary or superficial layer and the reticular or deeper layer. • Papillary layer. The outer layer of the dermis, lying directly beneath epidermis. Contains small, cone-shaped projections (called papillae) of elastic tissue that point upward to epidermis. Some papillae contain looped capillaries; others contain nerve fiber endings for the sense of touch called tactile corpuscles. Contains some melanin. Papillary layer of dermis houses nerve endings that provide body with sense of touch (touch, pain, heat, cold, pressure). • Reticular layer. The deeper layer of the dermis; contains fat cells, blood and lymph vessels, sweat and oil glands, hair follicles, arrector pili muscles. Supplies skin with oxygen and nutrients. • Subcutaneous tissue. Fatty layer found below dermis; also called adipose or subcutis tissue; varies in thickness according to age, sex, and general health. Gives smoothness and contour to body; contains fats for energy and acts as protective cushion for outer skin. Circulation is maintained through arteries and lymphatics.

How Skin Is Nourished Blood supplies nutrients Lymph removes toxins and cellular waste Arteries and vessels reach hair papillae, hair follicles, and skin glands HOW SKIN IS NOURISHED: Blood supplies nutrients or molecules from food such as protein, carbohydrates, and fats to the skin. The nutrients are required for cell life, repair, and growth. Lymph bathes the skin cells and removes toxins and cellular waste. Networks of arteries and lymph vessels in the subcutaneous tissue reach the hair papillae, hair follicles, and skin glands.

Nerves of the Skin Motor nerve fibers Sensory nerve fibers Secretory nerve fibers NERVES OF THE SKIN • Motor nerve fibers. Distributed to arrector pili muscles attached to hair follicles; cause gooseflesh when frightened or cold. • Sensory nerve fibers. React to heat, cold, touch, pressure, and pain. Send messages to the brain. Found in papillary layer; abundant in fingertips. • Secretory nerve fibers. Distributed to sweat and oil glands of the skin; regulate excretion of perspiration from sweat glands and control flow of sebum to surface of skin.

Skin Color Melanin Pheomelanin Eumelanin Hereditary SKIN COLOR: Depends, in part, on blood supply to the skin and melanin. • Melanin. The tiny grains of pigment (coloring matter) deposited in the stratum germinativum of the epidermis and the papillary layers of the dermis; protects against strong light rays. • Pheomelanin. Red to yellow in color. • Eumelanin. Dark brown to black. • Hereditary. Varies among races and nationalities. Dark skin contains more melanin; light skin contains less.

Skin Strength and Elasticity Collagen Elastin STRENGTH AND FLEXIBILITY OF SKIN: Two structures, collagen and elastin, make up 70% of the dermis and give strength, form, and flexibility to skin. • Collagen. A fibrous protein that gives skin form and strength. Healthy collagen fibers allow skin to stretch and contract. If fibers become weakened, skin can lose tone and suppleness, wrinkle, and sag. • Elastin. A protein base similar to collagen that forms elastic tissue. Gives skin flexibility and elasticity; helps skin regain its shape.

Glands of the Skin Sudoriferous glands (sweat) Sebaceous glands (oil) GLANDS OF THE SKIN: Skin contains two types of duct glands that extract materials from the blood to form new substances. • Sudoriferous or sweat glands. Consist of a coiled base or secretary coil and a tube-like duct that terminates at the skin surface to form the sweat pore. Sweat glands are more numerous on palms, soles, forehead, and armpits. They regulate body temperature and help eliminate waste; activity is increased by heat, exercise, emotions, and certain drugs. Excretion of sweat is controlled by nervous system. Normally 1 to 2 pints of salty liquid are eliminated daily. • Sebaceous or oil glands. Consist of little sacs whose ducts open into hair follicles. They secrete sebum that lubricates skin and preserves softness of hair. These glands are found everywhere on body except palms and soles. Flows through oil ducts leading to the mouths of hair follicles; when it becomes hardened and the duct becomes clogged, a blackhead is formed.

Functions of the Skin Protection Sensation Heat regulation Excretion Secretion Absorption FUNCTIONS OF THE SKIN • Protection. Protects body from injury and bacterial invasion. Outermost layer covered with thin layer of sebum to make it waterproof. • Sensation. Responds to heat, cold, touch, pressure and pain. • Heat regulation. Protects the body from the environment. • Excretion. Perspiration takes salt and other chemicals with it. • Secretion. Oil lubricates skin and keeps it soft and pliable and hair soft; emotional stress can increase flow of sebum. • Absorption. Limited, but does occur. Through the use of creams, female hormones and fatty materials such as lanolin can be absorbed through hair follicles and sebaceous gland openings.

Vitamins and Supplements Vitamin A: Supports overall health Vitamin C: Known as ascorbic acid Vitamin D: Best source is sunlight Vitamin E: Known as tocopherol MAINTAINING HEALTH OF SKIN: The old adage, “you are what you eat” still holds true. Proper dietary choices help regulate hydration, oil production, and overall function of the cells. Eating foods found in all three basic food groups—fats, carbohydrates, and proteins—is the best way to support healthy skin. VITAMINS AND SUPPLEMENTS • Aid in healing, softening, and fighting diseases of the skin. • Taking vitamins internally is best to support healthy skin. Also, some external applications have been found to be useful in nourishing the skin. VITAMIN A: Supports overall health of the skin. • Aids in health, function, and repair of skin cells • An antioxidant that can help prevent skin cancer • Can improve skin’s elasticity and thickness • Retinoic acid or Retin-A. Topical form that can be used to treat acne VITAMIN C: Also known as ascorbic acid. • Needed for proper repair of skin and tissues • Speeds up healing process • Promotes collagen production; fights the aging process VITAMIN D: Best source is sunlight (in limited amounts), fortified milk, and orange juice • Promotes healthy skin • Promotes rapid healing of skin • Also supports bone structure VITAMIN E: Also known as tocopherol. Used with vitamin A, can fight against and protect skin from harmful effects of sun’s rays. • Helps heal damage to skin’s tissues, whether used internally or externally • Topically, it can help heal structural damage on skin, including severe burns and stretch marks

Water and the Skin Comprises 50% to 70% of body weight Sustains health of cells Aids in elimination of toxins and waste Helps regulate body temperature Aids in proper digestion WATER AND THE SKIN: No one can live without water, an essential nutrient. • Comprises 50% to 70% of body’s weight. • Sustains the health of the cells • Aids in elimination of toxins and waste • Helps regulate body’s temperature • Aids in proper digestion

Consumption and Dehydration Divide body weight by 16. Result = Number of 8oz glasses of water needed daily. Dehydration slows metabolism. Water consumption reduces hunger pangs. Lack of water causes fatigue. 2% drop can trigger fuzzy memory. WATER CONSUMPTION: Water needs vary. Use this formula: Divide body weight by 16. The resulting number approximates how many 8-ounce glasses of water you should drink every day! DEHYDRATION: Seventy-five percent of Americans are chronically dehydrated. • Slows metabolism by as much as 3%. • Drinking lots of water can stop hunger pangs for dieters. • Lack of water causes fatigue. • A 2% drop in body water can trigger fuzzy memory. It can also cause trouble with basic math and cause difficulty in focusing on a computer screen.

Summary and Review Briefly describe healthy skin. Name the main divisions of the skin and layers within each division. How is the skin nourished? List the three types of nerve fibers found in skin. SUMMARY AND REVIEW The skin is the largest organ of the body and protects us from the environment, regulates body temperature, and provides sensation. The skin can be affected quite easily by most salon services. Therefore, it is important that cosmetologists know what products can penetrate the skin and what effects they will have on your clients. Let’s review. • Briefly describe healthy skin. ANSWER: Slightly moist, soft, and flexible with a texture (feel and appearance) that ideally is smooth and fine grained. It possesses a slightly acid reaction with good immunity responses to organisms that touch or try to enter it. • Name the main divisions of the skin and layers within each division. ANSWER: • Epidermis • Stratum germinativum (basal cell layer) • Stratum spinosum • Stratum granulosum • Stratum lucidum • Stratum corneum • Dermis • Papillary Layer • Reticular Layer • Subcutaneous (fatty tissue also called adipose or subcutis tissue) • How is the skin nourished? ANSWER: Blood and lymph, the clear fluids of the body that resemble blood plasma but contain only colorless corpuscles, supply nourishment. • List the three types of nerve fibers found in the skin. ANSWER: Motor, sensory, and secretory

What are the six important functions of the skin? Define dermatology. What is collagen? Name two types of glands contained in skin and describe their functions. What are the six important functions of the skin? Define dermatology. • What is collagen? ANSWER: A fibrous protein that gives the skin form and strength. • Name the two types of glands contained within the skin and describe their functions. ANSWER: • Sudoriferous or sweat glands excrete sweat from the skin, regulate body temperature, and help eliminate waste products from the body. • Sebaceous or oil glands secrete sebum, a fatty or oily secretion that lubricates the skin and preserves the softness of the hair. • What are the six important functions of the skin? ANSWER: Protection, sensation, heat regulation, excretion, secretion, absorption. • Define dermatology. ANSWER: The medical branch of science that deals with the study of the skin — its nature, structure, functions, diseases, and treatment.

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