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LET’S LOOK AT THE SKIN LET’S LOOK AT THE SKIN

CHAPTER 17CHAPTER 17

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OBJECTIVESOBJECTIVES

Describe the structure & Describe the structure & composition of the skincomposition of the skin

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INTRODUCTIONINTRODUCTION

One of the largest and most important One of the largest and most important organorgan of of the bodythe body

Healthy skin is slightly moist, soft, and flexible, Healthy skin is slightly moist, soft, and flexible, is acid, and free from diseaseis acid, and free from disease

Skin has immunity responses to organisms that Skin has immunity responses to organisms that touch or try to enter ittouch or try to enter it Unbroken skin is the bodies best defense Unbroken skin is the bodies best defense

against diseaseagainst disease

INTRODUCTIONINTRODUCTION

Its Its texturetexture ideally is smooth and fine grained ideally is smooth and fine grained Appendages of the skin are hair, nails, Appendages of the skin are hair, nails,

sweat, and oil glandssweat, and oil glands Scientific study of skin is called histologyScientific study of skin is called histology

The study of skin is important to form an The study of skin is important to form an effective program of skin care, beauty effective program of skin care, beauty services, and scalp treatmentsservices, and scalp treatments

INTRODUCTIONINTRODUCTION

Medical branch of science that deals with the Medical branch of science that deals with the study of skin and its nature, structure, study of skin and its nature, structure, functions, diseases, and treatment is called functions, diseases, and treatment is called dermatologydermatology

Dermatologist is a physician that treats the Dermatologist is a physician that treats the skin, its structures, & diseasesskin, its structures, & diseases

Esthetician is a specialists in the cleansing, Esthetician is a specialists in the cleansing, preservation of health, & beautification of the preservation of health, & beautification of the skin & bodyskin & body

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FACTS ABOUT THE SKINFACTS ABOUT THE SKIN

Skin varies in thicknessSkin varies in thickness Thinnest on the eyelids and thickest Thinnest on the eyelids and thickest

on the soles of the feeton the soles of the feet Continued pressure on any part of the Continued pressure on any part of the

skin can cause it to thicken and develop skin can cause it to thicken and develop a callusa callus

Skin on the scalp is constructed similar Skin on the scalp is constructed similar to the skin on the body, except the to the skin on the body, except the scalp has larger and deeper hair folliclesscalp has larger and deeper hair follicles

SkinSkin

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

The skin serves many purposes:The skin serves many purposes:     - serves as a barrier to the environment, - serves as a barrier to the environment,

and some glands (and some glands (sebaceoussebaceous) may have ) may have weak weak anti-infectiveanti-infective properties. properties.  - acts as a channel for communication to   - acts as a channel for communication to the outside world.the outside world.  - protects us from water loss, friction   - protects us from water loss, friction woundswounds, and impact wounds., and impact wounds.  - uses specialized pigment cells to protect   - uses specialized pigment cells to protect us from us from ultraviolet rays of the sunultraviolet rays of the sun..  - produces   - produces vitamin Dvitamin D in the in the epidermalepidermal layer, when it is exposed to the sun's rays.layer, when it is exposed to the sun's rays.  - helps regulate body temperature through   - helps regulate body temperature through sweat glandssweat glands..  - helps regulate metabolism.  - helps regulate metabolism.  - has esthetic and beauty qualities  - has esthetic and beauty qualities

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HISTOLOGY OF THE SKINHISTOLOGY OF THE SKIN

The skin contains two main divisions: The skin contains two main divisions: EpidermisEpidermis and and Dermis Dermis

Epidermis is the outermost layerEpidermis 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 bodyIs protective covering for the body Contains no blood vessels, but has Contains no blood vessels, but has

nerve endingsnerve endings

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LAYERS OF THE EPIDERMISLAYERS OF THE EPIDERMIS

Stratum corneum or horny layerStratum corneum or horny layer Outer layer, scale-like cells are being shedOuter layer, scale-like cells are being shed Contains protein keratinContains protein keratin Cells combine w/ a thin layer of oil to help make it Cells combine w/ a thin layer of oil to help make it

waterproof called the “acid mantle”waterproof called the “acid mantle” pH of the acid mantle ranges from ph 4.5 –5.5pH of the acid mantle ranges from ph 4.5 –5.5

Toughest layer and protective layer for the layers Toughest layer and protective layer for the layers below itbelow it

Stratum CorneumStratum Corneum

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

LAYERS OF THE EPIDERMISLAYERS OF THE EPIDERMIS

Stratum lucidumStratum lucidum Under the stratum corneumUnder the stratum corneum Clear layerClear layer Small transparent cells through which light Small transparent cells through which light

can passcan pass Only in the palms of the hands and soles of Only in the palms of the hands and soles of

the feetthe feet These cells are known as These cells are known as squamous squamous due to due to

their flat, scale-like appearancetheir flat, scale-like appearance

LAYERS OF THE EPIDERMISLAYERS OF THE EPIDERMIS

Stratum granulosum or granular Stratum granulosum or granular layerlayer Cells look like granulesCells look like granules Cells are almost dead & are pushed to the Cells are almost dead & are pushed to the

surface to replace cells that are shed surface to replace cells that are shed from the stratum corneum from the stratum corneum

LAYERS OF THE EPIDERMISLAYERS OF THE EPIDERMIS Stratum germinativumStratum germinativum

FFormerly known as the stratum mucosumormerly known as the stratum mucosum Also referred to as Also referred to as basalbasal or Malpighian layer or Malpighian layer

Single cell layer thickSingle cell layer thick This is where mitosis or cell division takes placeThis is where mitosis or cell division takes place Cells are constantly dividing a& producing new cells which Cells are constantly dividing a& producing new cells which

are pushed towards the surface of the skin to replace cells are pushed towards the surface of the skin to replace cells that have been shed as flake-like, lifeless residuethat have been shed as flake-like, lifeless residue

This process takes 15-25 daysThis process takes 15-25 days Deepest layer, responsible for growth, & skin colorDeepest layer, responsible for growth, & skin color Contains melanocytes, which produce melanin ( dark Contains melanocytes, which produce melanin ( dark

skin pigment ) which protects the sensitive cells skin pigment ) which protects the sensitive cells below from the ultraviolet rays of the sunbelow from the ultraviolet rays of the sun

As pigment granules move upward melanosomes are As pigment granules move upward melanosomes are “picked up”“picked up”

DermisDermis The second, larger layer of skin is called the dermis. The second, larger layer of skin is called the dermis. Its main roles are to regulate temperature and to supply Its main roles are to regulate temperature and to supply

the epidermis with nutrient-saturated blood. the epidermis with nutrient-saturated blood. The dermis is made up of fibroblasts, which produce The dermis is made up of fibroblasts, which produce

collagen connective tissues and which lend elasticity collagen connective tissues and which lend elasticity and support to the skin. and support to the skin.

It is the seat of hair follicles, nerve endings, and It is the seat of hair follicles, nerve endings, and pressure receptors. pressure receptors.

Furthermore, the dermis defends the body against Furthermore, the dermis defends the body against infectious invaders that can pass through the thin infectious invaders that can pass through the thin epidermis, the first defense against disease. epidermis, the first defense against disease.

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DERMIS LAYERDERMIS LAYER

The underlying, or inner layerThe underlying, or inner layer Also called true skin or coriumAlso called true skin or corium

25 times thicker than epidermis25 times thicker than epidermis Highly sensitive layer of connective tissuesHighly sensitive layer of connective tissues Contains blood vessels, lymph vessels, Contains blood vessels, lymph vessels,

nerves, sweat glands, oil glands, hair nerves, sweat glands, oil glands, hair follicles, arrector pili muscles, and papillaefollicles, arrector pili muscles, and papillae

Made up of two layersMade up of two layers Papillary layerPapillary layer Reticular layerReticular layer

The dermis is also subdivided into two The dermis is also subdivided into two divisions, the papillary dermis, and the divisions, the papillary dermis, and the reticular layer. reticular layer.

The papillary dermis is the main agent in The papillary dermis is the main agent in dermis function.dermis function.

It is from here that the dermis (1) supplies It is from here that the dermis (1) supplies nutrients to select layers of the epidermis and nutrients to select layers of the epidermis and (2) regulates temperature.(2) regulates temperature.

Both of these functions are accomplished with Both of these functions are accomplished with a thin but extensive vascular system that a thin but extensive vascular system that operates like vascular systems throughout the operates like vascular systems throughout the body.body.

Constriction and expansion control the amount Constriction and expansion control the amount of blood that flows through the skin and of blood that flows through the skin and dictate whether body heat is dispelled dictate whether body heat is dispelled carefully in times of heat or conserved for the carefully in times of heat or conserved for the cold. cold.

The reticular layer is much denser than the The reticular layer is much denser than the papillary dermis; it strengthens the skin, papillary dermis; it strengthens the skin, providing structure and elasticity.providing structure and elasticity.

As a foundation, it supports other components As a foundation, it supports other components of the skin, such as hair follicles, sweat glands, of the skin, such as hair follicles, sweat glands, and sebaceous glands. and sebaceous glands.

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PAPILLARY LAYERPAPILLARY LAYER

Outer layer of the dermisOuter layer of the dermis Called superficial layerCalled superficial layer Lies directly beneath the epidermisLies directly beneath the epidermis Contains small cone-shaped projections of Contains small cone-shaped projections of

elastic tissue called elastic tissue called papillaepapillae These contain looped These contain looped capillariescapillaries Contain nerve fiber ending, called Contain nerve fiber ending, called tacticle tacticle

corpuscles corpuscles that provide the body with the that provide the body with the sense of touchsense of touch

Also contains some melanin Also contains some melanin

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RETICULAR LAYERRETICULAR LAYER

Deeper layerDeeper layer Supplies the skin with oxygen and Supplies the skin with oxygen and

nutrientsnutrients Contains fat cells, blood vessels, lymph Contains fat cells, blood vessels, lymph

vessels, oil glands, sweat glands hair vessels, oil glands, sweat glands hair follicles and arrector pili musclesfollicles and arrector pili muscles

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TISSUES IN THE SKINTISSUES IN THE SKIN

Subcutaneous tissueSubcutaneous tissue Fatty layer found below the dermisFatty layer found below the dermis

Also called adipose or subcutisAlso called adipose or subcutis Varies in thickness according to the age, Varies in thickness according to the age,

sex and general health of a personsex and general health of a person Gives smoothness and contour to body, Gives smoothness and contour to body,

uses fats for energy, and is a protective uses fats for energy, and is a protective cushioncushion

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NERVES OF THE SKINNERVES OF THE SKIN

MOTOR NERVE FIBERSMOTOR NERVE FIBERS Distributed to the arrector piliDistributed to the arrector pili

Causes goose bumps, cold or frightenedCauses goose bumps, cold or frightened

SENSORY NERVE FIBERSSENSORY NERVE FIBERS Reacts to heat, cold, touch, pressure, and Reacts to heat, cold, touch, pressure, and

painpain SECRETORY NERVE FIBERSSECRETORY NERVE FIBERS

Distributed to sweat and oil glandsDistributed to sweat and oil glands Regulate excretion of perspiration from sweat Regulate excretion of perspiration from sweat

glands and controls flow of sebumglands and controls flow of sebum

Strength & flexibility of the skin & Strength & flexibility of the skin & collagencollagen

Two specific structures composed of flexible Two specific structures composed of flexible protein fibers found within the dermisprotein fibers found within the dermis CollagenCollagen Elastin Elastin

CollageCollagen n CollagenCollagen

Fibrous protein gives the skin form and strengthFibrous protein gives the skin form and strength Triple helix formed by three extended protein Triple helix formed by three extended protein

chains that wrap around on anotherchains that wrap around on another Large portion of the dermis & gives structural Large portion of the dermis & gives structural

support to the skinsupport to the skin Holds together all the structures found in this Holds together all the structures found in this

layerlayer Healthy collagen fibers allow the skin to stretch Healthy collagen fibers allow the skin to stretch

& contract & contract Unhealthy due to lack of moisture, environmental Unhealthy due to lack of moisture, environmental

damage, or frequent changes in weightdamage, or frequent changes in weight Skin will begin to lose its tone & suppleness, wrinkles & Skin will begin to lose its tone & suppleness, wrinkles &

sagging begin formingsagging begin forming

Strength & flexibility of the skin & Strength & flexibility of the skin & collagencollagen

ElastinElastin Collagen fibers are interwoven w/elastinCollagen fibers are interwoven w/elastin Elastin polypeptide chains are cross-linked Elastin polypeptide chains are cross-linked

together to form rubber-like, elastic fiberstogether to form rubber-like, elastic fibers Protein similar to collagenProtein similar to collagen Gives skin flexibility & elasticityGives skin flexibility & elasticity Helps the skin regain its shapeHelps the skin regain its shape

GLANDS OF THE SKINGLANDS OF THE SKIN

Two types of duct glands that Two types of duct glands that extract materials from the blood to extract materials from the blood to form new substancesform new substances

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SudoriferousSudoriferous or sweat glands or sweat glandsExcrete sweat, consist of a coiled Excrete sweat, consist of a coiled base or base or fundus fundus and a tube-like duct and a tube-like duct that terminates at the skin surfacethat terminates at the skin surface

Most numerous on the palms, soles, Most numerous on the palms, soles, forehead, and armpitsforehead, and armpits

Regulate body tempRegulate body temp

Sudoriferous or sweat glandsSudoriferous or sweat glands

Help to eliminate waste products Help to eliminate waste products from the bodyfrom the body– Increased by heat, exercise, Increased by heat, exercise,

emotions & certain drugsemotions & certain drugsControlled by nervous systemControlled by nervous system

– One to two pints of liquids One to two pints of liquids containing salts are eliminated daily containing salts are eliminated daily

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Sebaceous or oil glandsSebaceous or oil glands Consist of little sacs whose ducts open into the hair Consist of little sacs whose ducts open into the hair

follicles, not right into the skin like sweat glandsfollicles, not right into the skin like sweat glands Secrete sebumSecrete sebum

Fatty or oily secretion that lubricates the skin and preserves Fatty or oily secretion that lubricates the skin and preserves smoothness of hairsmoothness of hair

Found in all parts of the body, except on the palms & Found in all parts of the body, except on the palms & solessoles

Sebum flows through the oil ducts leading to the Sebum flows through the oil ducts leading to the mouths of the hair folliclesmouths of the hair follicles

If duct becomes clogged a blackhead is formed If duct becomes clogged a blackhead is formed

Summary Summary

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