The Integumentary systemThe Integumentary system two major componentstwo major components 1. cutaneous membrane 1. cutaneous membrane

A. epidermis /superficial epitheliumA. epidermis /superficial epithelium B. dermis/underlying connective tissues. B. dermis/underlying connective tissues.

2. accessory structures (located in the 2. accessory structures (located in the dermis)dermis) hair, nails, exocrine glands, blood vessels,hair, nails, exocrine glands, blood vessels,

sensory receptors for touch, pressure, sensory receptors for touch, pressure, temperature, and pain temperature, and pain

Deep to the dermis, the loose connective tissue of the Deep to the dermis, the loose connective tissue of the subcutaneous layer /superficial fascia/ subcutaneous layer /superficial fascia/ hypodermis, hypodermis, separates the integument from the deep fascia around separates the integument from the deep fascia around

other organsother organs

functions of the skinfunctions of the skin Protection Protection of organs against shocks, abrasion, of organs against shocks, abrasion,

and chemical attack.(stratified squamous and chemical attack.(stratified squamous epithelium)epithelium)

Excretion Excretion of salts, water, and organic wastes by of salts, water, and organic wastes by glands.glands.

Maintenance Maintenance of temperature through insulation of temperature through insulation or evaporation or evaporation

Synthesis of vitamin Synthesis of vitamin D3 steroid converted to D3 steroid converted to hormone calcitriol, important to normal calcium hormone calcitriol, important to normal calcium metabolism.metabolism.

Storage of Storage of nutrients.lipidsnutrients.lipids Detection Detection of touch, pressure, pain, and of touch, pressure, pain, and

temperature temperature

LAYERS OF THE EPIDERMISLAYERS OF THE EPIDERMIS In order, from the basal lamina toward In order, from the basal lamina toward

the free surface, are the the free surface, are the stratum germinativum(basale), stratum germinativum(basale), stratum spinosum, stratum spinosum, stratum granulosum,stratum granulosum, stratum lucidum,stratum lucidum, stratum corneum.stratum corneum.

Stratum granulosum

Stratum spinosum

stratum germinativum/stratum germinativum/basalebasale Forms epidermal ridges, which extend into the Forms epidermal ridges, which extend into the

dermis, dermis, Dermal projections called dermal papillae extend Dermal projections called dermal papillae extend

between adjacent epidermal ridgesbetween adjacent epidermal ridges The contours of the skin surface follow the ridge The contours of the skin surface follow the ridge

patterns - Fingerprintspatterns - Fingerprints Large basal cells, or Large basal cells, or germinative germinative stemstem cells, cells,

dominate the stratum germinativum. dominate the stratum germinativum. Skin surfaces that lack hair also contain Merkel Skin surfaces that lack hair also contain Merkel

cells that are sensitive to touch; when cells that are sensitive to touch; when compressed, they release chemicals that stimulate compressed, they release chemicals that stimulate sensory nerve endings. sensory nerve endings.

The brown tones of skin result from the pigment The brown tones of skin result from the pigment cells called cells called melanacytes, melanacytes, with cell processes with cell processes extending into more superficial layers.extending into more superficial layers.

Stratum granulosum

Stratum spinosum

Stratum SpinosumStratum Spinosum Each time a stem cell divides, one of the Each time a stem cell divides, one of the

daughter cells is pushed from the stratum daughter cells is pushed from the stratum germinativum into the stratum spinosum,germinativum into the stratum spinosum,

The stratum spinosum consists of 8 to 10 The stratum spinosum consists of 8 to 10 layers of cellslayers of cells

Langerhans cells, stimulate a defense Langerhans cells, stimulate a defense against (1) microorganisms that manage against (1) microorganisms that manage to penetrate the superficial layers of the to penetrate the superficial layers of the epidermis and (2) superficial skin epidermis and (2) superficial skin cancers.cancers.

Stratum granulosum

Stratum spinosum

Stratum GranulosumStratum Granulosum consists of three to five layers of keratinocytes consists of three to five layers of keratinocytes

displaced from the stratum spinosum. displaced from the stratum spinosum. By the time cells reach this layer, most have By the time cells reach this layer, most have

stopped dividing & they begin making large stopped dividing & they begin making large amounts of amounts of keratin keratin and and keratohyalin keratohyalin

Keratin is a tough fibrous protein component of Keratin is a tough fibrous protein component of hair and nails. hair and nails.

Keratohyalin forms dense granules that dehydrate Keratohyalin forms dense granules that dehydrate the cell and aggregate cross-linking of the keratin the cell and aggregate cross-linking of the keratin fibers. fibers.

The nuclei and other organelles disintegrate, and The nuclei and other organelles disintegrate, and the cells die. the cells die.

dehydration creates a tightly interlocked layer of dehydration creates a tightly interlocked layer of cells of keratin fibers surrounded by keratohyalin.cells of keratin fibers surrounded by keratohyalin.

Stratum granulosum

Stratum spinosum

Stratum LucidumStratum Lucidum

In the thick skin of the palms and In the thick skin of the palms and soles, a glassy soles, a glassy stratum lucidum stratum lucidum covers the stratum granulosum covers the stratum granulosum

The cells in the stratum lucidum are The cells in the stratum lucidum are flattened, densely packed, and filled flattened, densely packed, and filled with keratin.with keratin.

keratinocytes tkeratinocytes the body's most he body's most abundant epithelial cells form several abundant epithelial cells form several layers. layers.

thick skin, thick skin, on the palms and soles on the palms and soles have five layers have five layers

thin thin skin has only four layers skin has only four layers

Stratum granulosum

Stratum spinosum

Stratum CorneumStratum Corneum At the exposed surface of both thick skin and thin At the exposed surface of both thick skin and thin

skin skin contains 15 to 30 layers of keratinized cells. contains 15 to 30 layers of keratinized cells. remain tightly interconnected by desmosomes. remain tightly interconnected by desmosomes.

shed in large groups or sheets rather than shed in large groups or sheets rather than individually.individually.

15 to 30 days for a cell to move from the stratum 15 to 30 days for a cell to move from the stratum germinativum to the stratum corneum. germinativum to the stratum corneum.

The dead cells remain in the exposed stratum The dead cells remain in the exposed stratum corneum layer for an additional two weeks before corneum layer for an additional two weeks before they are shed they are shed

insensible perspirationinsensible perspiration Water from interstitial Water from interstitial fluids slowly evaporates into the surrounding air. fluids slowly evaporates into the surrounding air. You lose roughly 500 ml (about 1 pt) of water in You lose roughly 500 ml (about 1 pt) of water in this way each day. this way each day.

DermisDermis

The dermis is your "hide." It is leather The dermis is your "hide." It is leather The dense fibrous connective tissue has The dense fibrous connective tissue has two major regions— two major regions— papillary papillary and and reticularreticular The papillary layer The papillary layer is the upper region. It is is the upper region. It is

uneven and has fingerlike projections called uneven and has fingerlike projections called dermal papillae that create fingerprintsdermal papillae that create fingerprints

They contain capillaries, pain receptors (free They contain capillaries, pain receptors (free nerve endings) and touch receptors called nerve endings) and touch receptors called Meissner's corpuscles Meissner's corpuscles

The reticular layer The reticular layer is the deepest skin layer. is the deepest skin layer. It contains blood vessels, sweat and oil glands, It contains blood vessels, sweat and oil glands, and deep pressure receptors called and deep pressure receptors called Pacinian Pacinian corpuscles & corpuscles & phagocytes That attack bacteria phagocytes That attack bacteria

As we age we produce less collagen and elastin As we age we produce less collagen and elastin and fat decreases (wrinkles)and fat decreases (wrinkles)

hypodermishypodermis

Foundation that attaches to bone and muscleFoundation that attaches to bone and muscle Supplies skin with blood vessels and nervesSupplies skin with blood vessels and nerves Consists of loose connective tissueConsists of loose connective tissue Called subcutaneous tissue or superficial fasciaCalled subcutaneous tissue or superficial fascia ½ of the body’s fat is in hypodermis½ of the body’s fat is in hypodermis Insulates, energy, paddingInsulates, energy, padding Used to calculate total body fatUsed to calculate total body fat

Skin ColorSkin Color Three pigments contribute Three pigments contribute (1) melanin - amount and kind (yellow, reddish brown, or black) (1) melanin - amount and kind (yellow, reddish brown, or black) (2) carotene - orange-yellow found in carrots & orange, deep yellow, or (2) carotene - orange-yellow found in carrots & orange, deep yellow, or

leafy green vegetables.leafy green vegetables. (3) oxygen – amount bound to hemoglobin(3) oxygen – amount bound to hemoglobin people who produce a lot of melanin have brown-toned skin. people who produce a lot of melanin have brown-toned skin. the crimson color of oxygen-rich hemoglobin gives the skin a rosy the crimson color of oxygen-rich hemoglobin gives the skin a rosy

colorcolor When hemoglobin is poorly oxygenated, the skin appear blue, a When hemoglobin is poorly oxygenated, the skin appear blue, a

condition called condition called cyanosis cyanosis Cyanosis is common during heart failure and severe breathing Cyanosis is common during heart failure and severe breathing

disorders. disorders. skin color signals disease states:skin color signals disease states: • • Rubor, Rubor, Redness, Redness, or or erythema - erythema - embarrassment (blushing), fever, embarrassment (blushing), fever,

hypertension, inflammation, or allergy.hypertension, inflammation, or allergy. • • Pallor, Pallor, or or blanching - eblanching - emotional stress (fear, anger, and others), motional stress (fear, anger, and others),

Pale skin may also signifyPale skin may also signify anemia, low blood pressure, or impaired blood flow into the area.anemia, low blood pressure, or impaired blood flow into the area. • • Jaundice, Jaundice, or a or a yellow- cast – yellow- cast – liver disorder excess bile pigments in liver disorder excess bile pigments in

the bloodthe blood Bruises -Bruises - sites where blood has escaped and has clotted in the tissue sites where blood has escaped and has clotted in the tissue

spaces.(spaces.(hematomas) hematomas) unusual bruising may signify a deficiency of unusual bruising may signify a deficiency of vitamin C or hemophilia vitamin C or hemophilia

melaninmelanin yellow to brown to black, is produced by yellow to brown to black, is produced by melanocytes melanocytes sunlight stimulates the melanocytes to produce more sunlight stimulates the melanocytes to produce more

melanin (tanning) melanin (tanning) basale cells phagocytize the melanin & forms a protective basale cells phagocytize the melanin & forms a protective

"umbrella" over nuclei (DNA) from ultraviolet radiation in "umbrella" over nuclei (DNA) from ultraviolet radiation in sunlight. sunlight.

Freckles Freckles and and moles moles are where melanin is concentrated are where melanin is concentrated in one spot.in one spot.

excessive sun eventually damages the skin. excessive sun eventually damages the skin. It causes the elastic fibers to clump, leading to leathery It causes the elastic fibers to clump, leading to leathery

skin. It also depresses the immune system.skin. It also depresses the immune system. herpes simplex cold sore herpes simplex cold sore virus - are more likely to virus - are more likely to

have an eruption after sunbathing.have an eruption after sunbathing. Overexposure to the sun can also alter the DNA Overexposure to the sun can also alter the DNA

of skin cells and in this way lead to skin cancer. of skin cells and in this way lead to skin cancer.

Hairs and Hair FolliclesHairs and Hair Follicles millions of millions of hairs hairs all over the bodyall over the body Guards the head, shields the eyes Guards the head, shields the eyes

(eyelashes)(eyelashes) keep foreign particles out of the respiratory keep foreign particles out of the respiratory

tract (nose hairs)tract (nose hairs) A hair is produced by a A hair is produced by a hair folliclehair follicle rootroot - part of the hair enclosed in the follicle - part of the hair enclosed in the follicle Shaft -Shaft - projecting from the surface of scalp projecting from the surface of scalp

or skin or skin hair bulb matrix -hair bulb matrix - the growth zone the growth zone at the at the

inferior end of the follicleinferior end of the follicle As the daughter cells are pushed away from As the daughter cells are pushed away from

the growing region they become keratinized the growing region they become keratinized and die. and die.

medullamedulla - a central core surrounded by a - a central core surrounded by a bulky bulky cortex cortex layerlayer

cuticlecuticle - - single layer of cells overlap like roof single layer of cells overlap like roof shingles shingles

most heavily keratinized region most heavily keratinized region pigment is made by melanocytes in hair pigment is made by melanocytes in hair

bulbbulb dermal sheath dermal sheath -- dermal connective tissue dermal connective tissue

provides blood to hair bulb.provides blood to hair bulb. arrector pili - arrector pili - smooth muscle connecting smooth muscle connecting

hair follicle to dermal tissue (goose bumps)hair follicle to dermal tissue (goose bumps)

nailsnails

A A scalelike modification of the epidermis scalelike modification of the epidermis free edgefree edge body body (visible attached portion)(visible attached portion) root root (embedded in the skin)(embedded in the skin) Nailfolds - Nailfolds - overlapped skin foldsoverlapped skin folds cuticlecuticle - thick proximal nail fold - thick proximal nail fold nail bed - nail bed - stratum basale beneath the nailstratum basale beneath the nail nail matrixnail matrix - thickened proximal area - thickened proximal area is responsible for nail growthis responsible for nail growth produced by the matrix nails become keratinized and die (nonliving)produced by the matrix nails become keratinized and die (nonliving) Nails look pink because of the rich blood supply in the underlying Nails look pink because of the rich blood supply in the underlying

dermisdermis Lunula - Lunula - white crescent over nail matrixwhite crescent over nail matrix

glands of the Skinglands of the SkinCutaneous GlandsCutaneous Glands (all are (all are exocrine exocrine glands)glands)

Exocrine Glands -Exocrine Glands - release secretions to release secretions to surface via ductssurface via ductstwo groups: two groups: 1. 1. sebaceous glands sebaceous glands and and 2. 2. sweat glands. sweat glands. Both Both formed by stratum basale & push formed by stratum basale & push into dermis.into dermis.

1. Sebaceous (Oil) Glands – 1. Sebaceous (Oil) Glands – - all over- all over except on the palms of hands and feet. except on the palms of hands and feet. Their ducts usually empty into a hair follicle but Their ducts usually empty into a hair follicle but some open directly onto the skin surface.(lips, some open directly onto the skin surface.(lips,

eyelids, genitalia)eyelids, genitalia) sebum (sebum (seb = seb = grease), mixture of oily substances grease), mixture of oily substances

and fragmented cells lubricate skin & and fragmented cells lubricate skin & kill kill bacteria, bacteria, male sex hormones produced in both sexes during male sex hormones produced in both sexes during

adolescence increase sebumadolescence increase sebum Whitehead - Whitehead - a sebaceous gland's duct becomes a sebaceous gland's duct becomes

blocked blocked by sebumby sebum blackhead - blackhead - the accumulated material oxidizes, the accumulated material oxidizes,

dries and dries and darkensdarkens Acne -Acne - active infection of the sebaceous glands active infection of the sebaceous glands

can be mild or extremely severe, leading to can be mild or extremely severe, leading to permanent scarring. permanent scarring.

Seborrhea Seborrhea (("cradle cap“) in infants – "cradle cap“) in infants – overactivity of the sebaceous glands on the scalp overactivity of the sebaceous glands on the scalp starts as pink, raised lesions that gradually form a yellow to starts as pink, raised lesions that gradually form a yellow to

brown crust that sloughs off as oily dandruff.brown crust that sloughs off as oily dandruff.

2. Sweat Glands (2. Sweat Glands (sudoriferoussudoriferous= sweat)—= sweat)— more than 2.5 million per person. more than 2.5 million per person. There are two types merocrine/There are two types merocrine/eccrine eccrine and and apocrine.apocrine. Merocrine/eccrine glands Merocrine/eccrine glands -- more numerous all over more numerous all over

the body. produce the body. produce sweat, psweat, primarily water plus salts, rimarily water plus salts, vitamin C, traces of metabolic wastes (ammonia, urea, vitamin C, traces of metabolic wastes (ammonia, urea, uric acid), and lactic acid (attracts mosquitoes). uric acid), and lactic acid (attracts mosquitoes).

Sweat is acidic (pH from 4 to 6), and inhibits growth of Sweat is acidic (pH from 4 to 6), and inhibits growth of bacteria, which are always present on the skin surface. bacteria, which are always present on the skin surface.

Apocrine glands -Apocrine glands - confined to axillary and genital areas confined to axillary and genital areas larger than eccrine glands, their ducts empty into hair larger than eccrine glands, their ducts empty into hair

follicles. follicles. Their secretion contains fatty acids, proteins, salt & waterTheir secretion contains fatty acids, proteins, salt & water

may have a milky or yellowish color. odorless, but when bacteria may have a milky or yellowish color. odorless, but when bacteria that that live live on skin use its proteins and fats it has an unpleasant on skin use its proteins and fats it has an unpleasant odor.odor.

Apocrine glands begin to function during puberty under Apocrine glands begin to function during puberty under the influence of androgens. the influence of androgens. Their precise function is not yet known, but they are activated by Their precise function is not yet known, but they are activated by

nerve fibers during pain and stress and during sexual foreplay.nerve fibers during pain and stress and during sexual foreplay.

eyelopmental Aspects of Skin l/and Body Membraneseyelopmental Aspects of Skin l/and Body Membranes During the fifth and sixth months of fetal develop ment, the soon-to-be-born infant is covered with a downy type of hair During the fifth and sixth months of fetal develop ment, the soon-to-be-born infant is covered with a downy type of hair

called called lanugo lanugo (lah-noo'go), but this hairy cloak has usually been shed by birth. When a baby is born, its skin is covered with (lah-noo'go), but this hairy cloak has usually been shed by birth. When a baby is born, its skin is covered with vernix caseosa vernix caseosa (ver'niks kah-se-o'sah). This white, cheesy-looking substance, produced by the seba ceous glands, protects (ver'niks kah-se-o'sah). This white, cheesy-looking substance, produced by the seba ceous glands, protects the baby's skin while it is floating in its water-filled sac inside the mother. The newborn's skin is very thin, and blood the baby's skin while it is floating in its water-filled sac inside the mother. The newborn's skin is very thin, and blood vessels can easily be seen through it. Commonly, there are accumulations in the sebaceous glands, which ap pear as small vessels can easily be seen through it. Commonly, there are accumulations in the sebaceous glands, which ap pear as small white spots called white spots called milia milia (mil'e-ah), on the baby's nose and forehead. These normally disappear by the third week after (mil'e-ah), on the baby's nose and forehead. These normally disappear by the third week after birth. As the baby grows, its skin becomes thicker and moist, and more subcutaneous tat is deposited.birth. As the baby grows, its skin becomes thicker and moist, and more subcutaneous tat is deposited.

During adolescence, the skin and hair become ,,more oily as sebaceous glands are activated, and acne may appear. Acne During adolescence, the skin and hair become ,,more oily as sebaceous glands are activated, and acne may appear. Acne usually subsides in early adulthood, and the skin reaches its optimal ap pearance when we are in our 20s and 30s. Then usually subsides in early adulthood, and the skin reaches its optimal ap pearance when we are in our 20s and 30s. Then visible changes in the skin begin to appear as it is continually assaulted by abrasion, chemicals, wind, sun, and other visible changes in the skin begin to appear as it is continually assaulted by abrasion, chemicals, wind, sun, and other irritants and as its pores become clogged with air pollutants and bacteria. As a re sult, pimples, scales, and various kinds of irritants and as its pores become clogged with air pollutants and bacteria. As a re sult, pimples, scales, and various kinds of der matitis der matitis (der"mah-ti'tis), or skin inflammation, be come more common.(der"mah-ti'tis), or skin inflammation, be come more common.

During old age, the amount of subcutaneous tissue decreases, leading to the intolerance to cold so common in the elderly. During old age, the amount of subcutaneous tissue decreases, leading to the intolerance to cold so common in the elderly. The skin also becomes drier (because of decreased oil production and de clining numbers of collagen fibers) and, as a The skin also becomes drier (because of decreased oil production and de clining numbers of collagen fibers) and, as a result, it may become itchy and bothersome. Thinning of the skin, another result of the aging process, makes it more result, it may become itchy and bothersome. Thinning of the skin, another result of the aging process, makes it more susceptible to bruising and other types of injuries. The decreasing elasticity of the skin, along with the loss of subcutaneous susceptible to bruising and other types of injuries. The decreasing elasticity of the skin, along with the loss of subcutaneous fat, allows bags to form under our eyes, and our jowls begin to sag. This loss of elasticity is speeded up by sunlight, so one fat, allows bags to form under our eyes, and our jowls begin to sag. This loss of elasticity is speeded up by sunlight, so one of the best things you can do for your skin is to shield it from the sun by wearing sunscreens and protective clothing. In of the best things you can do for your skin is to shield it from the sun by wearing sunscreens and protective clothing. In doing so, you will also be decreasing the chance of skin cancer. Although there is no way to avoid the aging of the skin, doing so, you will also be decreasing the chance of skin cancer. Although there is no way to avoid the aging of the skin, good nutrition, plenty of fluids, and cleanliness help delay the process.good nutrition, plenty of fluids, and cleanliness help delay the process.

Hair loses its luster as we age, and by age 50 the number of hair follicles has dropped by one-third and continues to Hair loses its luster as we age, and by age 50 the number of hair follicles has dropped by one-third and continues to decline, resulting in hair thinning and some degree of baldness, or decline, resulting in hair thinning and some degree of baldness, or alopecia alopecia (al"o-pe'she-ah), in most people. Many men (al"o-pe'she-ah), in most people. Many men become ob viously bald as they age, a phenomenon called become ob viously bald as they age, a phenomenon called male pattern baldness. male pattern baldness. A bald man is not really hairless— he A bald man is not really hairless— he does have hairs in the bald area. But because those hair follicles have begun to degenerate, the hairs are colorless and does have hairs in the bald area. But because those hair follicles have begun to degenerate, the hairs are colorless and very tiny (and may not even emerge from the follicle). Such hairs are called very tiny (and may not even emerge from the follicle). Such hairs are called vellus (veil = vellus (veil = wool) hairs. Another wool) hairs. Another phenomenon of aging is graying hair. Like balding, this is usually genetically controlled by a "delayed-action" gene. Once phenomenon of aging is graying hair. Like balding, this is usually genetically controlled by a "delayed-action" gene. Once the gene takes effect, the amount of melanin deposited in the hair decreases or becomes entirely absent, which results in the gene takes effect, the amount of melanin deposited in the hair decreases or becomes entirely absent, which results in gray-to-white hair.gray-to-white hair.

S Certain events can cause hair to gray or fall out prematurely. For example, many people have claimed that they turned S Certain events can cause hair to gray or fall out prematurely. For example, many people have claimed that they turned gray nearly overnight be cause of some emotional crisis in their life. In addi tion, we know that anxiety, protein-deficient gray nearly overnight be cause of some emotional crisis in their life. In addi tion, we know that anxiety, protein-deficient diets, therapy with certain chemicals (chemotherapy), ra diation, excessive vitamin A, and certain fungal dis eases diets, therapy with certain chemicals (chemotherapy), ra diation, excessive vitamin A, and certain fungal dis eases (ringworm) can cause both graying and hair loss. However, when the cause of these conditions is not genetic, hair loss is (ringworm) can cause both graying and hair loss. However, when the cause of these conditions is not genetic, hair loss is usually not permanent. •usually not permanent. •