INTEGUMENTARY SYSTEM. COMPONENTS OF THE INTEGUMENTARY SYSTEM Figure 5-1.

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INTEGUMENTARY SYSTEM

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

Transcript of INTEGUMENTARY SYSTEM. COMPONENTS OF THE INTEGUMENTARY SYSTEM Figure 5-1.

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INTEGUMENTARY SYSTEM

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COMPONENTS OF THE INTEGUMENTARY SYSTEM

Figure 5-1

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COMPONENTS OF THE INTEGUMENTARY SYSTEM

Integumentary* System Components•Cutaneous** membrane

• Epidermis – top layer (thinner)• Dermis – below epidermis (thicker)• Accessory structures

•Subcutaneous layer (hypodermis)

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

* integumentary means “covering”

* cutaneous means “skin”

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Main Functions of the Integument1. Protection / Waterproofing

keratinized layer of dead cellswhite blood cells

2. Temperature maintenancesweat glandscapillaries

3. Synthesis and storage of nutrientssubcutaneous adipose tissue

4. Sensory receptiontemp., touch, pain

5. Excretion and secretionsweatoil / wax6. Synthesizes vitamin D with UV

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

FUNCTION OF THE INTEGUMENT

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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

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THE EPIDERMIS: THICK AND THIN SKIN

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THE STRUCTURE OF THE EPIDERMIS

Figure 5-2

stratum = layer

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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)

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CELL LAYERS OF THE EPIDERMIS •STRATUM GERMINATIVUM

• Basal layer• Contain Merkel cells (found on skin that lack hair) sense

touch then release chemicals.• Contain Stem cells

•Mitotic cell division layer•Source of replacement cells. High mechanical stress,

the cells stem cells divide more rapidly and the depth of the epidermis increases, thus a callus.

• Contain Melanocytes•Synthesize melanin = brown pigment•Convert cholesterol related steroid to vitamin d

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CELL LAYERS OF THE EPIDERMIS • Intermediate layers

• Stratum spinosum (spiny layer)• 8-10 layers of cells• Cells look like miniature pin cushions• Some cells still divide• Contain Langerhan cells (Immune)• May contain superficial cancer cells

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CELL LAYERS OF THE EPIDERMIS • Stratum granulosum (grainy layer)• 3-5 Layers of cells

•Keratin granules in cytoplasm•No cell division •Begin making large amounts of Keratin

• Stratum lucidum (clear layer)•Found in thick skin•Flattened, densely packed and filled with

Keratin

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CELL LAYERS OF THE EPIDERMIS •Stratum corneum•15-30 Layers of cells

• Most superficial layer• Flattened (squamous) cells• Dead cells• Abundant keratin

•Keratinized (also, cornified)•Tough, water-resistant protein•Only maintenance is to coar surface with lipid

sedretions from sebaceous and sweat glands•Water-resistant not waterproof.

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CELL LAYERS OF THE EPIDERMIS

TIMING OF MOVEMENT BETWEEN LAYERS:• Stratum Basal cells take to 15- 30 days to reach

Stratum Corneum.• Cells remain in S. Corneum an additional 2

weeks before they are shed.• Replace cells of the skin once every two months

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INSENSIBLE PERSPIRATION VS. SENSIBLE PERSPIRATION

Insensible Perspiration: water loss from interstitial fluids slowly penetrates the stratum corneum to the surface and evaporates. 1 pint of water per day is lost through the skin

Sensible Perspiration: produced by sweat glands

Damage to the epidermis can speed up the water loss• Blisters• Burns

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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

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SOURCES OF SKIN COLOR

Melanocytes

Figure 5-3

Melanin travel in vesicles to c.spinosum where they transfer to intact cells. Lysosomes of those cells will destroy melanin transferred. Everyone has at least 1000 melanocytes/mm2

2000 melanocytes/mm2 found

in the cheek, forehead, nipples, and genital regions

Albinos too! Their melanocytes lack the ability

to produce melanin

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SOURCES OF SKIN COLOR• Caucasians-

melanin travels to s. spinosum

• Black people-more melanin vesicles that are larger and extend to the s. granulosum

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UV RADIATION AND MELANINTransfer of melanosomes (vesicles) to keratinocytes.

In the presence of UV radiation, melanosomes migrate to the superficial surface of the nucleus to protect the DNA from harmful radiation.

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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)

When ultraviolet light penetrates the outer layers of the skin, not only are the tanning cells stimulated but there are changes in its collagen (supporting structure) too.

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The collagen becomes weakened which can result in permanent changes and premature aging. Gradually there is a wrinkling and leathering effect in addition to drying of the skin.

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TWO IMPORTANT TYPES OF SKIN CANCER

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EPIDERMIS: STRUCTURE/FUNCTION

Key NoteThe 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)

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DERMISStrong, flexible connective tissue: your “hide”Cells: fibroblasts, macrophages, mast cells, WBCsFiber types: collagen, elastic, reticularRich supply of nerves and vesselsCritical role in temperature regulation (the vessels)Two layers (see next slides)

• Papillary – areolar connective tissue; includes dermal papillae

• Reticular – “reticulum” (network) of collagen and reticular fibers

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LAYERS OF THE DERMIS (from top down)

Papillary layer • Most superficial layer of dermis consists of areolar

CT with collagen and elastic fibers.• Dermal papillae form dermal ridges that form our

fingerprints, palm prints and footprints.• Reticular layer- 80 % of dermis• - consist of dense irregular CT• - named for its network (reticulum) of collagen fibers

• Supports, nourishes epidermis• Provides sensory nerves, lymphatics, and

capillaries*papillae = “little fingers”

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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)

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DERMIS: STRETCH MARKS

Elastin fibers break and cannot recoil, skin wrinkles creating a network of stretch marks. Why does the degree of stretch marks vary among women during pregnancy?

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DERMIS: LINES OF CLEAVAGE• Caused by the orientation

of parallel bundles of collagen and elastic fibers in dermis.

• Follow lines of tension • Bundles are aligned to

resist tension• A cut parallel to a line of

cleavage will remain closed. (less scarring, heal faster)

• If you cut at right angles the cut will remain open because the elastic fibers will recoil.

• Surgeons plan accordingly

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DERMIS: DERMAL BLOOD SUPPLY• Cutaneous Plexus: network of vessel connecting the hypodermis to the dermis• Papillary Plexus: branching network of vessels that follow the contour between

epidermal ridge and dermal papillary layer.

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DERMIS: DERMAL BLOOD SUPPLYUlcer (bedsores)-

Chronic lack of circulation kills epidermal cells. Bacterial infections occur. If left untreated the dermal tissue will degenerate

Necrosis- dermal tissue that has

degenerated. Birthmarks:

Capillary hemangioma, Cavernous hemangioma

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DERMIS: STRUCTURE/FUNCTION

Key NoteThe 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.

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THE SUBCUTANEOUS LAYER (HYPODERMIS)

•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•Also called “superficial fascia”

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THE SUBCUTANEOUS LAYER (HYPODERMIS)

Why are Babies Fat?

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SKIN ACCESSORIES

1.Hair: (pilus/pili) derived from keratin2.Glands: sebaceous and sweat (sudoriferous glands).3.Nails: are produced from keratin

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Functions of hair• Warmth – less in man than other mammals• Sense light touch of the skin (Root Hair Plexus)• Protection – scalp from UV and blows to head• Prevent foreign particles from entering

(nasal,ears,lashes)Parts

• Root imbedded in skin• Shaft projecting above skin surface

Make up of hair – hard keratin. Three concentric layers• Medulla (core)• Cortex (surrounds medulla)• Cuticle (single layers, overlapping)

HAIR AND HAIR FOLLICLES

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HAIR AND HAIR FOLLICLES

Figure 5-5(b)

The arrector pili muscles are what produce “goose bumps.”

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HAIR AND HAIR FOLLICLES

*

Hair papilla is connective tissue________________

Hair bulb: epithelial cells surrounding papilla

Arrector pili----Skeletal or Arrector pili----Skeletal or Smooth Muscle????Smooth Muscle????

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HAIR (not the musical)HAIR FACTS:•5 million on the human body•Found everywhere but palms, soles, inside fingers and toes, nipples, parts of genitalia•98% on general body not the head! 100,000 on head•Lose about 50 hairs on your head each day

TYPES OF HAIR:• Vellus: fine, short hairs• Terminal: deeply pigmented,longer, courser hair.

(mostly head hair & eyelash/eyebrows) HAIR COLOR

• Amount of melanin for black or brown; distinct form of melanin for red

• White: decreased melanin and air bubbles in the medulla• Genetically determined though influenced by hormones and

environment

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HAIR GROWTH CYCLE

• One scalp hair grows for 2-5 years at a rate of .33mm per day (1 mm every 4 days…..10 cm every month. 1 inch every three months!

• Uncut hair has many different growth cycles• At the end of 2-5 years, the hair follicle becomes inactive and gets smaller cutting off the root. Old Club hair gets

pushed out when hair follicle is activive again and grow a new hair.Club Hair

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GLANDS

(Holocrine)

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GLANDS: Sebaceous GlandsSebaceous glands produce an oily secretion called sebum. Usually

open into a hair follicle. Sebaceous Follicles are large Sebaceous glands and never produce

hair. Found on face, back ,chest, nipples, and male sex organs.• Their secretion is called Sebum and its holocrine in nature • Sebum is composed of triglycerides, cholesterol, proteins, and

electrolytes. • Sebum is bactericidal i.e. limits the growth of bacteria• If Sebaceous glands get blocked a furuncle (boil) is formed.• Sebaceous glands are sensitive to change in sex hormones…

acne• Abnormally active Sebaceous glands in adults may inflame and

epidermal cells and scale off……Dandruff (Cradle cap in children)• Sebum keeps skin moist and flexible and gives hair a sheen

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GLANDS: Sebaceous Glands

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GLANDS: Sebaceous GlandsThe Structure of Sebaceous Glands and Their

Relationship to Hair Follicles

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GLANDS: Sudoriferous “sweat” glands

Figure 5-7

SUDORIFEROUS “SWEAT” GLANDS 2 kinds: •APOCRINE •MEROCRINE. https://www.youtube.com/watch?v=E5aJTpiwakIhttps://www.youtube.com/watch?v=o_eqZkZFm5A

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SWEAT GLANDS: Sudoriferous/Merocrine

• Merocrine: most numerous (2-5 MILLION);

• produce watery perspiration for cooling body; • Sweat is 99% water, salt, urea,/pH of 4.8-6.8• most abundant on palms, soles and forehead. • Not as deep as apocrine. • Sensible Perspiration- when all are working at maximum

rate the rate of perspiration can exceed 1 gallon per hour!!

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SWEAT GLANDS: Sudoriferous/ApocrineSudoriferous “sweat” glands – are of 2 kinds; apocrine and merocrine

Apocrine: •Present in groin, axilla, anal, areola, and beard regions; •Ducts open into hair follicle; •Sweat is thicker milkier due to fatty acids. •Nutrient rich for bacteria. •Strong odor is due to bacterial decay.•Scent glands that respond to stress and sexual stimulation•Become fully functional at puberty.•Open into hair follicles

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GLANDS: OTHERMammary Glands: • Similar to apocrine

sweat glands. • Controlled by

pituitary and sex hormones.

Ceruminous Glands: • Modified sweat

glands in ear canal. • Secretions combine

with sebaceous glands and form a mixture call cerumen (ear wax).

• Cerumen and tiny hairs keep particles and insects from reaching the eardrum.

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NAILS

• Made of hard keratin• Corresponds to hooves and claws• Grows from nail matrix• Protects the exposed tips of fingers and toes; limits their distortion under mechanical stress.• Nail Root: an epithelial fold reaching to underlying bone.• Eponychium or Cuticle: Stratum corneum extends over exposed nail• Lunula: The pale crescent of the nail caused by obscured blood vessels not as exposed as in the nail bed.

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NAILSNAIL PITTING: ice pick-like depressions in the nails psoriasis and alopecia.

NAIL CLUBBING: tips of the fingers enlarge and the nails curve around the fingertips Result of low oxygen in the blood and could be a sign of various types of lung disease. Nail clubbing is also associated with inflammatory bowel disease, cardiovascular disease, liver disease and AIDS.

SPOON NAILS: soft nails that look scooped out. The depression usually is large enough to hold a drop of liquid.sign of iron deficiency anemia or a liver condition known as hemochromatosis, in which your body absorbs too much iron from the food you eat. Spoon nails can also be associated with heart disease and hypothyroidism.

TERRY'S NAILS: most of the nails appear white except for a narrow pink band at the tip.Terry's nails can sometimes be attributed to aging or a sign of a serious underlying condition, such as liver disease, congestive heart failure, kidney failure or diabetes.

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NAILS

↑BEAU'S LINES: are indentations that run across the nails. The indentations can appear when growth at the area ↑under the cuticle is interrupted by injury or severe illness. Conditions associated with Beau's lines include uncontrolled diabetes and peripheral vascular disease, as well as illnesses associated with a high fever, such as scarlet fever, measles, mumps and pneumonia. Beau's lines can also be a sign of zinc deficiency.

←ONYCHOLYSIS Detached nails. The separated part of the nail becomes opaque with a white, yellow or green tinge.Detached nails can be associated with injury or infection or thyroid disease and psoriasis also can cause nail separation.

←YELLOW NAIL SYNDROME: nails thicken and new growth slows. This results in a yellowish discoloration of the nails.It is often a sign of respiratory disease, such as chronic bronchitis. Yellow nail syndrome can also be related to swelling of the hands (lymphedema).

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FINGERPRINTS, PALMPRINTS, FOOTPRINTS

Dermal papillae lie atop dermal ridgesElevate the overlying epidermis into epidermal ridgesAre “sweat films” because of sweat poresGenetically determined

Flexion creasesDeep dermis, from continual folding

FibersCollagen: strength and resilienceElastic fibers: stretch-recoil

• Striae: stretch marksTension lines (or lines of cleavage)

• The direction the bundlesof fibers are directed

The dermis is the receptive site for the pigment of tattoos

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FINGERPRINTS

Sweat Pores on tips of fingers leave a stamp of sweat on whatever surface they touch

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SKIN INJURY AND REPAIR

Four Stages in Skin Healing• Inflammation

• Blood flow increases• Phagocytes attracted

• Scab formation• Cell division and

migration• Scar formation

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Figure 5-92 of 5Copyright © 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

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Figure 5-93 of 5Copyright © 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

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 circulationin the area. Clotting around the edgesof the affected area partially isolatesthe region.

Sweat gland

Scab

Macrophagesand

fibroblasts

Migratoryepithelialcells

Granulationtissue

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Figure 5-94 of 5Copyright © 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.

Fibroblasts

Fibroblasts = connective tissue cells that secrete fibers.

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Figure 5-95 of 5Copyright © 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.

Fibroblasts

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.

Scartissue

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Figure 5-91 of 5Copyright © 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

One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblastactivity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating.

Fibroblasts

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, andmore of these cells are arriving with the enhanced circulation in the area. Clotting around the edges of the affected area partially isolates the region.

Sweat gland

Scab

Macrophagesand

fibroblasts

Migratoryepithelialcells

Granulationtissue

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.

Scartissue