THE INTEGUMENTARY SYSTEM
A large amount of the dust in you home is actually dead skin. Humans shed about 600,000 particles of skin every hour – about 1.5 pounds a year. By 70 years of age, an average person will have lost 105 pounds of skin. Wow!
The skin is the largest organ in the body and weighs 12 – 15% of the total body weight.
Although polar bears have both white and transparent (see through) fur, their skin is actually black.
The color of human skin depends on the amount of pigment melanin that the body produces. Small amounts of melanin result in light skin while large amounts result in dark skin.
The outer layer of your skin is the epidermis, it is found thickest on the palms of your hands and soles of your feet (around 1.5mm thick).
The average human being has 21 sq ft of skin and about 300 million skin cells.
Hmmmmmm…….Did you know?
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GENERAL STRUCTURE OF THE INTEGUMENT (INTRODUCTION)
Cutaneous membrane is skin
Two layers of skin
1. Epidermis (superficial)
2. Dermis (deep)
Accessory structures
Hair, nails, and some exocrine glands
Hypodermis or subcutaneous layer
Deep to the dermis
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FIGURE 5-1 THE GENERAL STRUCTURE OF THE INTEGUMENTARY SYSTEM.
Cutaneous Membrane
Epidermis
Papillary layer
Reticular layer
Dermis
Hypodermis
Accessory Structures
Hair shaft
Pore of sweatgland duct
Touch receptor
Sebaceous gland
Arrector pili muscle
Sweat gland duct
Hair follicle
Pressure receptor
Nerve fibers
Sweat gland
Fat
Artery
VeinCutaneousplexus
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FIVE GENERAL FUNCTIONS OF THE INTEGUMENT (INTRODUCTION)
1. Protection
Skin covers underlying tissues and prevents fluid loss
2. Temperature maintenance
Skin regulates heat exchange with the environment
3. Synthesis and storage of nutrients
Epidermis synthesizes vitamin D3
Dermis stores lipids in adipose tissue
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FIVE GENERAL FUNCTIONS OF THE INTEGUMENT (INTRODUCTION)
4. Sensory reception
Receptors for pain, pressure, touch, and
temperature detect stimuli and send
information to nervous system
5. Excretion and secretion
Glands excrete salts, water, and organic wastes
Specialized mammary glands secrete milk
WHAT IS EPITHELIA?
Layers of cells that cover internal or external surfaces
Cover the skin Line internal passageways that
communicate to the outside world and internal cavities
Must remain firmly attached to basement membrane and to one another to be effective in protecting other tissues
WHAT IS A CELL JUNCTION?
Specialized attachment sites 3 common junctions
Tight junctions Gap junctions desmosomes
JUNCTIONS
Tight Lipid layers of adjacent plasma membranes (cell
membranes) are tightly bound together by interlocking membrane proteins
Prevent passage of water and solutes betw cells Gap
Two cells are held together by embedded membrane proteins called connexons
Most abundant in cardiac muscle and smooth muscle tissue
Desmosome Plasma membranes of 2 cells locked together by
CAM’s and proteoglycans
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FUNCTIONS OF EPITHELIA (4-2)
Provide physical protection
Control permeability
Provide sensation
Produce specialized secretions (glandular
epithelium) Exocrine glands
Endocrine glands
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CELL LAYERS AND CELL SHAPES (4-3)
Classification is based on layers
Simple epithelium: single layer of cells
Stratified epithelium: several layers of cells
Classification is based on shape
Squamous epithelia: thin and flat
Cuboidal epithelia: square shaped
Columnar epithelia: tall, slender rectangles
© 2013 Pearson Education, Inc.Table 4-1 Classifying Epithelia
© 2013 Pearson Education, Inc.Figure 4-4a Simple Epithelia.
Cytoplasm
Nucleus
Connective tissueLining of peritoneal cavity
LM x 238
Simple Squamous Epithelium
LOCATIONS: Epithelia lining ventral body cavities; lining heartand blood vessels; portions ofkidney tubules (thin sections of nephron loops); inner lining ofcornea; alveoli (air sacs) of lungs
FUNCTIONS: Reduces friction;controls vessel permeability;performs absorption and secretion
© 2013 Pearson Education, Inc.Figure 4-4b Simple Epithelia.
Connectivetissue
Nucleus
Cuboidalcells
Kidney tubule LM x 650
Basementmembrane
LOCATIONS: Glands; ducts;portions of kidney tubules; thyroidgland
FUNCTIONS: Limited protection,secretion, absorption
Simple Cuboidal Epithelium
© 2013 Pearson Education, Inc.Figure 4-4c Simple Epithelia.
LM x 350
Microvilli
Cytoplasm
Nucleus
BasementmembraneConnective
tissueIntestinal lining
LOCATIONS: Lining ofstomach, intestine, gallbladder,uterine tubes, and collectingducts of kidneys
FUNCTIONS: Protection,secretion, absorption
Simple Columnar Epithelium
© 2013 Pearson Education, Inc.Figure 4-5a Stratified Epithelia.
Stratified Squamous Epithelium
Squamoussuperficial cells
Stem cellsBasementmembraneConnective
tissue LM x 310Surface of tongue
LOCATIONS: Surface ofskin; lining of mouth, throat,esophagus, rectum, anus,and vaginaFUNCTIONS: Provides physicalprotection against abrasion,pathogens, and chemical attack
© 2013 Pearson Education, Inc.Figure 4-5b Stratified Epithelia.
CytoplasmCilia
Nuclei
BasementmembraneConnective
tissueLM x 350
Pseudostratified Ciliated Columnar Epithelium
Trachea
LOCATIONS: Lining ofnasal cavity, trachea, andbronchi; portions of malereproductive tract
FUNCTIONS: Protection,secretion, move mucuswith cilia
© 2013 Pearson Education, Inc.Figure 4-5c Stratified Epithelia.
Transitional Epithelium
Epithelium(relaxed)
Basement membraneConnective tissue andsmooth muscle layers LM x 400
Epithelium(stretched)
Basement membraneConnective tissue andsmooth muscle layersFull bladder
Empty bladder
Urinary bladderLM x 400
LOCATIONS: Urinarybladder; renal pelvis;ureters
FUNCTIONS: Permitsexpansion and recoilafter stretching
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THE EPIDERMIS (5-1) Is stratified squamous epithelium
Thick skin has five layers
Thin skin has four layers
Layers are called strata, from deep to
superficial Stratum basale
Three intermediate layers Stratum spinosum, stratum granulosum, and
stratum lucidum
Stratum corneum
CAM’S, DESMOSOMES, AND BASEMENT MEMBRANES
CAM = cell adhesion molecules Transmembrane proteins Proteoglycans (protein-polysaccharide mixture)help bind to
CAM Desmosome = plasma membranes of two cells are
locked together by CAMs and proteoglycans Spot Desmosome = desmosomes that form small discs Hemidesmosome = resemble half of a spot desomosome
and attach cell to basement mem. Basement Membrane = lies between the epithelium
and underlying tissue Provides strength, resists distortion, and provides a barrier
that restricts movement of proteins and other large molecules from the underlying connective tissue into the epithelium
© 2013 Pearson Education, Inc.Figure 4-3 The Surfaces of Epithelial Cells.
Cilia
Microvilli
Apicalsurface
Golgiapparatus
Nucleus
Mitochondria
Basement membrane
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STRATUM BASALE (5-1)
Also called stratum germinativum
Attached to basement membrane by hemidesmosomes
Forms epidermal ridges down into dermis
Dermis has dermal papillae up into epidermis
Epidermis is avascular (bloodless)
Ridges and papillae increase surface area for diffusion
between dermis and epidermis
Blackhead:A plug of sebum in a hair follicle, darkened by oxidationSebum is an oily substance secreted by the sebaceous glands that helps prevent hair and skin from drying out.
DO NOW
Explain the process of exfoliating skin (facial scrubs/body scrubs). What layer of skin does it involve? Also, explain why this layer is unsuitable for the growth of many microorganisms…
Would exfoliating skin cause breakouts? Prevent breakouts? Explain.
© 2013 Pearson Education, Inc.FIGURE 5-2 THE STRUCTURE OF THE EPIDERMIS.
Surface
Stratumcorneum
Stratumlucidum
Stratumgranulosum
Stratumspinosum
Stratum basale
Basementmembrane
Dermis
Thick skin LM x 210
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INTERMEDIATE STRATA (5-1)
Stratum spinosum is the result of stem cell
division
Stratum granulosum cells make a lot of keratin
A protein that provides water resistance and the
foundation for hair and nails
Stratum lucidum cells are densely packed into a
highly keratinized layer
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STRATUM CORNEUM (5-1)
Contains 15–30 layers of keratinized
or cornified dead cells
Cells are connected via desmosomes
and are therefore shed in large groups
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SKIN COLOR (5-2)
Role of pigmentation
Carotene is orange-yellow, accumulates
in epidermis, and comes from orange-
colored foods
Melanin is brown, yellow-brown, or black,
produced by melanocytes near stratum
basale cells, absorbs ultraviolet (UV)
radiation protecting deeper layers
UV RADIATION
A small amount is good = stimulates vitamin D3 synthesis
Too much = mild to serious burns Prolonged exposure can cause
wrinkling and skin cancer (result from the chromosomal damage in stem cells of the stratum basale or in melanocytes
A-B-C-D-E OF SUSPICIOUS MARKS ON SKIN
© 2013 Pearson Education, Inc.FIGURE 5-3 MELANOCYTES.
Melanocytesin stratumbasale
Melaninpigment
Basementmembrane
LM x 600Melanocytes
Melanosome
MelaninpigmentMelanocyte
Basementmembrane
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SKIN COLOR (5-2)
Role of dermal circulation
Oxygenated blood is bright red resulting in a flushed,
red skin color when dermal blood vessels dilate
Short-term paling of the skin occurs with
vasoconstriction
Cyanosis, a bluish coloration, occurs when blood
oxygen supplies are diminished
Response to extreme cold or result of circulatory or respiratory
disorders (heart failure or severe asthma)
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BENEFICIAL EFFECTS OF SUNLIGHT ON SKIN (5-3)
Vitamin D3 is derived from:
A cholesterol-related steroid in the epidermis
when exposed to sunlight
Vitamin D3 is modified by:
The liver and the kidneys into calcitriol,
essential for calcium and phosphorus
absorption in the small intestine
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DETRIMENTAL EFFECTS OF SUNLIGHT ON SKIN (5-3)
Skin cancers
Basal cell carcinoma is most common
Originating in stratum basale
Squamous cell carcinoma found in more
superficial layers
Malignant melanoma is most dangerous
Usually begins from a mole, and can metastasize
through the lymphatic system
MORE MALIGNANT MELANOMA
© 2013 Pearson Education, Inc.FIGURE 5-4 SKIN CANCERS.
Basal cell carcinoma Melanoma
Christmas
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THE DERMAL PAPILLARY LAYER (5-4)
Named for the dermal papillae
Just deep to, and projects up into, the
epidermis
Contains capillaries and nerves
supplying the epidermis
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THE DERMAL RETICULAR LAYER (5-4) Interwoven meshwork of dense, irregular
connective tissue As well as mixed in cells of connective tissue proper
Elastic and collagen fibers are present Combine to establish the right balance of flexibility
and stability
Collagen fibers extend from up into the dermal papillae Down into the hypodermis
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THE DERMAL RETICULAR LAYER (5-4)
Hair follicles and sweat glands derived from
epidermis
Extend down into the dermis
Cutaneous plexus—blood vessels from the
hypodermis—extends up into the reticular layer
Blood vessels, lymphatics, and nerves
Supply nutrients, eliminate wastes, control secretions,
and respond to stimuli
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THE HYPODERMIS (5-5)
Also called the subcutaneous layer
Deep to the dermis without a clear line separating them
Not actually part of the integument
But stabilizes the skin to underlying tissues
Made of areolar tissue with many adipose cells
No vital organs in area make it an ideal site for
subcutaneous injections
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HAIR AND HAIR FOLLICLES (5-6)
Are accessory organs of the integumentary
system
Hairs are nonliving structures
Project above the skin surface everywhere except:
The soles of the feet, palms of the hands, sides of the
fingers and toes, the lips, and portions of the external
genitalia
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HAIR AND HAIR FOLLICLES (5-6)
Epidermal layers invaginate into the dermis to
form hair follicles
Epithelium at the base of follicle caps over the
hair papilla
Connective tissue that contains capillaries and nerves
Epithelial stem cells divide to form hair matrix
surrounding the papilla
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HAIR AND HAIR FOLLICLES (5-6)
Hair matrix grows, making hair longer, and
cells become keratinized and die
Halfway to skin surface, it becomes the hair
root
Above the surface it is called the hair shaft
Shaft has three layers of dead cells
From outer to inner: cuticle, cortex, and medulla
© 2013 Pearson Education, Inc.FIGURE 5-5B HAIR FOLLICLES AND HAIRS.
This drawing shows a longitudinal section of a single hair follicle and hair.
Hair papilla
Hair matrix
Connectivetissue sheath
Hair root
Arrectorpili muscle
Sebaceousgland
Hair shaft
Boundarybetweenhair shaftand hair root
© 2013 Pearson Education, Inc.FIGURE 5-5A HAIR FOLLICLES AND HAIRS.
Sebaceous gland
Hair shaft
Hair
Hypodermis
Connective tissue sheath of hair
Cortex
MedullaHair matrixHair papilla
In this section of skin of the scalp, notice that the two hair follicles extend into the hypo-dermis.
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FUNCTIONS OF HAIR (5-6)
Protects the scalp
Prevents entry of foreign particles into nose,
eyes, and ears
Prevents injury via sensory perception
Expresses emotional state by hair standing
up, due to contraction of arrector pili muscle
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HAIR COLOR (5-6)
Differences due to type and amount of
melanin from melanocytes
Aging results in less pigment
production
Causing gray or white hair
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SEBACEOUS GLANDS OF THE SKIN (5-7)
Secrete oily sebum into the hair follicle
Sebaceous follicles secrete sebum directly onto:
Skin of face, back, chest, nipples, and external genitalia
Sebaceous glands are sensitive to hormonal
changes
Inflamed glands can result in acne
© 2013 Pearson Education, Inc.FIGURE 5-6 SEBACEOUS GLANDS AND THEIR RELATIONSHIP TO HAIR FOLLICLES.
Sebaceous glandSebaceous follicle
Epidermis
Dermis
Hypodermis
Hair removed
Wall of hair follicle
Basementmembrane
Discharge ofsebum
Breakdown ofcell membranes
Mitosis and growth
Basal cells
Sebaceous gland LM x 150
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SWEAT GLANDS (5-7)
Also called sudoriferous glands
Include two types
1. Apocrine sweat glands
2. Merocrine sweat glands
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APOCRINE SWEAT GLANDS (5-7)
Become active at puberty
Secrete sticky, cloudy sweat into hair
follicles in armpits, around nipples, and
in the pubic region
Sweat is food source for bacteria on
skin, increasing odor
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MEROCRINE SWEAT GLANDS (5-7)
Also called eccrine sweat glands Very numerous with high numbers on soles
and palms Coiled tubular structure secretes watery
perspiration directly onto surface of skin Sweat also contains electrolytes, urea, and
organic nutrients Sodium chloride gives it the salty taste
Function is to cool body through evaporation
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NAILS (5-8)
Protect tips of fingers and toes
Visible nail body
Made of dense, keratinized cells recessed
under surrounding epithelium
Nail bed
Deeper level of epithelium covered by nail
body
Nail root Where the nail is produced
Covered by the cuticle
Lunula Pale crescent near root
© 2013 Pearson Education, Inc.FIGURE 5-8 THE STRUCTURE OF A NAIL.
Free edge
Nail body
Nailbed LunulaCuticle
(eponychium)Nail root
(site of growth)
Epidermis Dermis Bone of fingertip
WHAT YOUR FINGERNAILS TELL YOU…Wasting away of Nails; Nail loses luster and becomes smaller, Injury or disease
Thickened Nail Plate: Poor circulation; fungal infection; heredity; mild, persistent trauma to the nail
Pitted Nails sometimes yellow-to=brown: Eczema or psoriasis; hair loss condition
Very soft Nails: Contact with strong alkali; malnutrition; endocrine problems; chronic arthritis
Spoon shaped Nails: Iron deficiency; thyroid disease
Clublike Nails - swollen finger ends: Chronic respiratory or heart problems; cirrhosis of the liver
WHAT YOUR FINGERNAILS TELL YOU…
Horizontal ridges: Injury; infection; nutrition
Longitudinal ridges: Aging, poor absorption of vitamins and minerals; thyroid disease; kidney failure
Colorless: May indicate anemia.
Red or deep pink: Can indicate a tendency to poor peripheral circulation.
Yellow: Could indicate fungus, diabetes, psoriasis, use of tetracycline, or heredity.
White, crumbly, soft: May be a result of a fungus infection
No Moons: Possible underactive thyroid; genetics
Overlarge Moons: Possible Overactive thyroid; genetics; self-induced trauma (habit tick)
Complete loss of Nail: Trauma
WHAT YOUR FINGERNAILS TELL YOU…
Nail Plate Loose: Injury; nail psoriasis; fungal or bacterial infections; medicines; chemotherapy; thyroid disease; Raynaud’s phenomenon; lupus
Brittle, split Nails: Nail dryness, nails in contact with irritating substances (detergents, chemicals, polish remover); silica deficiency
Pale, brittle nails, spoon-shaped or with ridges down the length - can signify anemia; this lack of iron can be due to inadequate nutrition
Thick, distorted fingernails can signify a fungal condition: If you have a fungal infection distorted fingernails could also be due to arterial sclerosis, so see your health care conditioner to rule that out.
Clubbed fingernails can signify a problem with your blood flow. See your health care practitioner.
White spots on your nails - is often due to a vitamin or mineral deficiency.
WHAT YOUR FINGERNAILS TELL YOU…Brittle and lifting easily from your nail beds, along with dry skin, always feeling cold and hair falling out - could indicate a problem with your thyroid gland;
Excessively flexible nails, may signify deficiency of calcium and sometimes protein.
Infected Nails: RED, TENDER, SWOLLEN, PUS: Bacterial or yeast infection
Whitish hue at base of fingernails, may signify liver trouble. If it's a matter of cleansing your liver, taking milk thistle (silymarin) capsules, available at your health food store;
Splinters that don't hurt - could be subacute bacterial endocarditis, a very serious condition. See your health care practitioner immediately!
Purple or black: Usually due to trauma, or may also be a sign of vitamin B12 deficiency.
Bluish nails - probably means you aren't getting enough oxygen; combined with a cough and shortness of breath means heart failure or chronic lung trouble and you should see you health care practitioner;
A Brown or Black streak:, that begins at the base of the nail and extends to its tip could be a diagnostic clue to a potentially dangerous melanoma. See your healthcare provider.
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REPAIR OF THE INTEGUMENT (5-9)
Skin regeneration occurs because: Stem cells of epithelium and connective tissue
undergo cell division Replacing lost or damaged tissue
Four steps of skin repair
1. Scab formation
2. Tissue granulation
3. Scab removal
4. Scar formation
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REPAIR OF THE INTEGUMENT (5-9)
Scab formation
A blood clot that forms on the surface
Is a temporary "patch" and can help prevent
additional microbes from invading the injury
Granulation tissue
Is formed from the combination of the fibrin blood clot,
fibroblasts, and capillaries
Macrophages clean up debris
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REPAIR OF THE INTEGUMENT (5-9)
Clot removal and a decline of capillaries
Scar is formed from remaining meshwork of collagen
fibers
A fibroblast is a type of cell that makes connective tissue
Degree of scar dependent on severity and location of
injury and age of patient
Keloid scars are thicker, raised, smooth, and shiny
epidermal surface
© 2013 Pearson Education, Inc.FIGURE 5-9 EVENTS IN SKIN REPAIR.
Epidermis
Dermis
Mast cells
Migratingepithelialcells
Macrophagesand fibroblasts
Granulationtissue
Fibroblasts
Scartissue
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EFFECTS OF BURNS (5-9)
Can be caused by chemicals, heat,
radiation, and electrical shock
Severity depends on depth into the
tissues, and the total area affected
© 2013 Pearson Education, Inc.TABLE 5-1 A COMMON CLASSIFICATION OF BURNS
BURNS…
1ST DEGREE BURN
Layers: Epidermis
Appearance: Red, swollen
Sensation: Painful
Healing Time: 1 week
2ND DEGREE BURN
Layers: Extends into superficial (papillary) or deep (reticular) dermis.
Appearance: Red w/ clear or bloody blisters
Sensation: Painful
Healing Time: 2-3 weeks
3RD DEGREE BURN
Layers: Extends into entire dermis.
Appearance: stiff white/brown
Sensation: Painless
Healing Time: Requires Excision (removal by cutting)
4TH DEGREE BURN Layers: Extends through
skin, subcutaneous tissue and into underlying muscle and bone
Appearance: Black; charred with eschar (dead tissue).
Sensation: Painless
Healing Time: Requires Excision
DALLAS WIENS – 4TH DEGREE BURN VICTIM
Dallas Wiens is the first United States recipient of a full face transplant, performed at the Brigham and Women's Hospital during the week of March 14, 2011.
EFFECTS OF AGING ON THE INTEGUMENT (5-10)
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EFFECTS OF AGING ON THE INTEGUMENT (5-10)
Skin injuries and infections are more common
Likely due to a thinning of the epidermis
Sensitivity of immune system is reduced
Mainly due to a decrease of macrophages residing in the
skin
Muscles become weaker and bone strength
decreases
Due to a decline in vitamin D3
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EFFECTS OF AGING ON THE INTEGUMENT (5-10)
Sensitivity to sun exposure increases
Due to lower amount of melanin production
Skin becomes dryer and flakier
Due to reduction in glandular secretions
Hair thins and loses color
Due to low-functioning follicles and decreased
melanocyte activity
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EFFECTS OF AGING ON THE INTEGUMENT (5-10)
Sagging and wrinkling of the skin occurs Due to decrease in elastic network, more noticeable
when skin has been exposed to a lot of sunlight
Ability to lose heat is reduced Due to reduced dermal blood supply and less active
sweat glands
Skin repairs more slowly Due to slower stem cell division, increasing the threat
of infection in cuts