1 LET’S LOOK AT THE SKIN CHAPTER 17

2 OBJECTIVES Describe the structure & composition of the skin Describe the structure & composition of the skin

3INTRODUCTION One of the largest and most important organ of the body One of the largest and most important organ of the body Healthy skin is slightly moist, soft, and flexible, is acid, and free from disease Healthy skin is slightly moist, soft, and flexible, is acid, and free from disease Skin has immunity responses to organisms that touch or try to enter it Skin has immunity responses to organisms that touch or try to enter it Unbroken skin is the bodies best defense against disease Unbroken skin is the bodies best defense against disease

INTRODUCTION Its texture ideally is smooth and fine grained Its texture ideally is smooth and fine grained Appendages of the skin are hair, nails, sweat, and oil glands Appendages of the skin are hair, nails, sweat, and oil glands Scientific study of skin is called histology Scientific study of skin is called histology The study of skin is important to form an effective program of skin care, beauty services, and scalp treatments The study of skin is important to form an effective program of skin care, beauty services, and scalp treatments

INTRODUCTION Medical branch of science that deals with the study of skin and its nature, structure, functions, diseases, and treatment is called dermatology Medical branch of science that deals with the study of skin and its nature, structure, functions, diseases, and treatment is called dermatology Dermatologist is a physician that treats the skin, its structures, & diseases Dermatologist is a physician that treats the skin, its structures, & diseases Esthetician is a specialists in the cleansing, preservation of health, & beautification of the skin & body Esthetician is a specialists in the cleansing, preservation of health, & beautification of the skin & body

5 FACTS ABOUT THE SKIN Skin varies in thickness Skin varies in thickness Thinnest on the eyelids and thickest on the soles of the feet Thinnest on the eyelids and thickest on the soles of the feet Continued pressure on any part of the skin can cause it to thicken and develop a callus Continued pressure on any part of the skin can cause it to thicken and develop a callus Skin on the scalp is constructed similar to the skin on the body, except the scalp has larger and deeper hair follicles Skin on the scalp is constructed similar to the skin on the body, except the scalp has larger and deeper hair follicles

Skin Skin is the largest organ in the body, both by weight and surface area. In adults, the weight of your skin accounts for about 16% of your total body weight. Normally the skin separates the internal environment from the external. However, skin diseases and infections can compromise that barrier. Infections and diseases also affect the nails and hair. Skin is the largest organ in the body, both by weight and surface area. In adults, the weight of your skin accounts for about 16% of your total body weight. Normally the skin separates the internal environment from the external. However, skin diseases and infections can compromise that barrier. Infections and diseases also affect the nails and hair.skin diseasesnailshairskin diseasesnailshair

The skin serves many purposes: The skin serves many purposes: - serves as a barrier to the environment, and some glands (sebaceous) may have weak anti- infective properties. - acts as a channel for communication to the outside world. - protects us from water loss, friction wounds, and impact wounds. - uses specialized pigment cells to protect us from ultraviolet rays of the sun. - produces vitamin D in the epidermal layer, when it is exposed to the sun's rays. - helps regulate body temperature through sweat glands. - helps regulate metabolism. - has esthetic and beauty qualities - serves as a barrier to the environment, and some glands (sebaceous) may have weak anti- infective properties. - acts as a channel for communication to the outside world. - protects us from water loss, friction wounds, and impact wounds. - uses specialized pigment cells to protect us from ultraviolet rays of the sun. - produces vitamin D in the epidermal layer, when it is exposed to the sun's rays. - helps regulate body temperature through sweat glands. - helps regulate metabolism. - has esthetic and beauty qualitiessebaceousanti- infectivewoundsultraviolet rays of the sunvitamin Depidermal sweat glandssebaceousanti- infectivewoundsultraviolet rays of the sunvitamin Depidermal sweat glands

6 HISTOLOGY OF THE SKIN The skin contains two main divisions: Epidermis and Dermis The skin contains two main divisions: Epidermis and Dermis Epidermis is the outermost layer Epidermis is the outermost layer Also called the cuticle or scarf layer Also called the cuticle or scarf layer It is the thinnest layer of the skin It is the thinnest layer of the skin Is protective covering for the body Is protective covering for the body Contains no blood vessels, but has nerve endings Contains no blood vessels, but has nerve endings

7 LAYERS OF THE EPIDERMIS Stratum corneum or horny layer Stratum corneum or horny layer Outer layer, scale-like cells are being shed Outer layer, scale-like cells are being shed Contains protein keratin Contains protein keratin Cells combine w/ a thin layer of oil to help make it waterproof called the “acid mantle” Cells combine w/ a thin layer of oil to help make it waterproof called the “acid mantle” pH of the acid mantle ranges from ph 4.5 –5.5 pH of the acid mantle ranges from ph 4.5 –5.5 Toughest layer and protective layer for the layers below it Toughest layer and protective layer for the layers below it

Stratum Corneum This stratum corneum may be as thin as a few cells, or as thick as 50 or more, again depending on its location on the body. The corneum of the scalp, for instance, may be very thin, perhaps five cells thick, while that of the elbow is more likely to be upwards of 50 cells thick. So the body provides for high- contact areas by maintaining a thicker and, therefore, more durable layer of protection. This stratum corneum may be as thin as a few cells, or as thick as 50 or more, again depending on its location on the body. The corneum of the scalp, for instance, may be very thin, perhaps five cells thick, while that of the elbow is more likely to be upwards of 50 cells thick. So the body provides for high- contact areas by maintaining a thicker and, therefore, more durable layer of protection.

LAYERS OF THE EPIDERMIS Stratum lucidum Stratum lucidum Under the stratum corneum Under the stratum corneum Clear layer Clear layer Small transparent cells through which light can pass Small transparent cells through which light can pass Only in the palms of the hands and soles of the feet Only in the palms of the hands and soles of the feet These cells are known as squamous due to their flat, scale-like appearance These cells are known as squamous due to their flat, scale-like appearance

LAYERS OF THE EPIDERMIS Stratum granulosum or granular layer Stratum granulosum or granular layer Cells look like granules Cells look like granules Cells are almost dead & are pushed to the surface to replace cells that are shed from the stratum corneum Cells are almost dead & are pushed to the surface to replace cells that are shed from the stratum corneum

LAYERS OF THE EPIDERMIS Stratum germinativum Stratum germinativum F ormerly known as the stratum mucosum F ormerly known as the stratum mucosum Also referred to as basal or Malpighian layer Also referred to as basal or Malpighian layer Single cell layer thick Single cell layer thick This is where mitosis or cell division takes place This is where mitosis or cell division takes place Cells are constantly dividing a& producing new cells which are pushed towards the surface of the skin to replace cells that have been shed as flake-like, lifeless residue Cells are constantly dividing a& producing new cells which are pushed towards the surface of the skin to replace cells that have been shed as flake-like, lifeless residue This process takes days This process takes days Deepest layer, responsible for growth, & skin color Deepest layer, responsible for growth, & skin color Contains melanocytes, which produce melanin ( dark skin pigment ) which protects the sensitive cells below from the ultraviolet rays of the sun Contains melanocytes, which produce melanin ( dark skin pigment ) which protects the sensitive cells below from the ultraviolet rays of the sun As pigment granules move upward melanosomes are “picked up” As pigment granules move upward melanosomes are “picked up”

Dermis  The second, larger layer of skin is called the dermis.  Its main roles are to regulate temperature and to supply the epidermis with nutrient-saturated blood.  The dermis is made up of fibroblasts, which produce collagen connective tissues and which lend elasticity and support to the skin.  It is the seat of hair follicles, nerve endings, and pressure receptors.  Furthermore, the dermis defends the body against infectious invaders that can pass through the thin epidermis, the first defense against disease.

8 DERMIS LAYER The underlying, or inner layer The underlying, or inner layer Also called true skin or corium Also called true skin or corium 25 times thicker than epidermis 25 times thicker than epidermis Highly sensitive layer of connective tissues Highly sensitive layer of connective tissues Contains blood vessels, lymph vessels, nerves, sweat glands, oil glands, hair follicles, arrector pili muscles, and papillae Contains blood vessels, lymph vessels, nerves, sweat glands, oil glands, hair follicles, arrector pili muscles, and papillae Made up of two layers Made up of two layers Papillary layer Papillary layer Reticular layer Reticular layer

 The dermis is also subdivided into two divisions, the papillary dermis, and the reticular layer.  The papillary dermis is the main agent in dermis function.  It is from here that the dermis (1) supplies nutrients to select layers of the epidermis and (2) regulates temperature.  Both of these functions are accomplished with a thin but extensive vascular system that operates like vascular systems throughout the body.

 Constriction and expansion control the amount of blood that flows through the skin and dictate whether body heat is dispelled carefully in times of heat or conserved for the cold.  The reticular layer is much denser than the papillary dermis; it strengthens the skin, providing structure and elasticity.  As a foundation, it supports other components of the skin, such as hair follicles, sweat glands, and sebaceous glands.

9 PAPILLARY LAYER Outer layer of the dermis Outer layer of the dermis Called superficial layer Called superficial layer Lies directly beneath the epidermis Lies directly beneath the epidermis Contains small cone-shaped projections of elastic tissue called papillae Contains small cone-shaped projections of elastic tissue called papillae These contain looped capillaries These contain looped capillaries Contain nerve fiber ending, called tacticle corpuscles that provide the body with the sense of touch Contain nerve fiber ending, called tacticle corpuscles that provide the body with the sense of touch Also contains some melanin Also contains some melanin

10 RETICULAR LAYER Deeper layer Deeper layer Supplies the skin with oxygen and nutrients Supplies the skin with oxygen and nutrients Contains fat cells, blood vessels, lymph vessels, oil glands, sweat glands hair follicles and arrector pili muscles Contains fat cells, blood vessels, lymph vessels, oil glands, sweat glands hair follicles and arrector pili muscles

11 TISSUES IN THE SKIN Subcutaneous tissue Subcutaneous tissue Fatty layer found below the dermis Fatty layer found below the dermis Also called adipose or subcutis Also called adipose or subcutis Varies in thickness according to the age, sex and general health of a person Varies in thickness according to the age, sex and general health of a person Gives smoothness and contour to body, uses fats for energy, and is a protective cushion Gives smoothness and contour to body, uses fats for energy, and is a protective cushion

12 NERVES OF THE SKIN MOTOR NERVE FIBERS MOTOR NERVE FIBERS Distributed to the arrector pili Distributed to the arrector pili Causes goose bumps, cold or frightened Causes goose bumps, cold or frightened SENSORY NERVE FIBERS SENSORY NERVE FIBERS Reacts to heat, cold, touch, pressure, and pain Reacts to heat, cold, touch, pressure, and pain SECRETORY NERVE FIBERS SECRETORY NERVE FIBERS Distributed to sweat and oil glands Distributed to sweat and oil glands Regulate excretion of perspiration from sweat glands and controls flow of sebum Regulate excretion of perspiration from sweat glands and controls flow of sebum

Strength & flexibility of the skin & collagen Two specific structures composed of flexible protein fibers found within the dermis Two specific structures composed of flexible protein fibers found within the dermis Collagen Collagen Elastin Elastin

Collagen Collagen Collagen Fibrous protein gives the skin form and strength Fibrous protein gives the skin form and strength Triple helix formed by three extended protein chains that wrap around on another Triple helix formed by three extended protein chains that wrap around on another Large portion of the dermis & gives structural support to the skin Large portion of the dermis & gives structural support to the skin Holds together all the structures found in this layer Holds together all the structures found in this layer Healthy collagen fibers allow the skin to stretch & contract Healthy collagen fibers allow the skin to stretch & contract Unhealthy due to lack of moisture, environmental damage, or frequent changes in weight Unhealthy due to lack of moisture, environmental damage, or frequent changes in weight Skin will begin to lose its tone & suppleness, wrinkles & sagging begin forming Skin will begin to lose its tone & suppleness, wrinkles & sagging begin forming

Strength & flexibility of the skin & collagen Elastin Elastin Collagen fibers are interwoven w/elastin Collagen fibers are interwoven w/elastin Elastin polypeptide chains are cross-linked together to form rubber-like, elastic fibers Elastin polypeptide chains are cross-linked together to form rubber-like, elastic fibers Protein similar to collagen Protein similar to collagen Gives skin flexibility & elasticity Gives skin flexibility & elasticity Helps the skin regain its shape Helps the skin regain its shape

GLANDS OF THE SKIN Two types of duct glands that extract materials from the blood to form new substances Two types of duct glands that extract materials from the blood to form new substances

13 Sudoriferous or sweat glands Sudoriferous or sweat glands Excrete sweat, consist of a coiled base or fundus and a tube-like duct that terminates at the skin surface Excrete sweat, consist of a coiled base or fundus and a tube-like duct that terminates at the skin surface Most numerous on the palms, soles, forehead, and armpits Most numerous on the palms, soles, forehead, and armpits Regulate body temp Regulate body temp

Sudoriferous or sweat glands Help to eliminate waste products from the body Help to eliminate waste products from the body –Increased by heat, exercise, emotions & certain drugs Controlled by nervous system Controlled by nervous system –One to two pints of liquids containing salts are eliminated daily

14 Sebaceous or oil glands Sebaceous or oil glands Consist of little sacs whose ducts open into the hair follicles, not right into the skin like sweat glands Consist of little sacs whose ducts open into the hair follicles, not right into the skin like sweat glands Secrete sebum Secrete sebum Fatty or oily secretion that lubricates the skin and preserves smoothness of hair Fatty or oily secretion that lubricates the skin and preserves smoothness of hair Found in all parts of the body, except on the palms & soles Found in all parts of the body, except on the palms & soles Sebum flows through the oil ducts leading to the mouths of the hair follicles Sebum flows through the oil ducts leading to the mouths of the hair follicles If duct becomes clogged a blackhead is formed If duct becomes clogged a blackhead is formed

Summary A cosmetologist who has a thorough understanding of the skin, its structure has a better position to give clients professional advice on scalp, facial and hand care