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chapter 5
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M A R I E J I M D I A N E O . P A Y O T , R M T , M S M T
INTEGUMENTARY SYSTEM
SKIN OR CUTANEOUS MEMBRANE
in inward
tegere to cover
Skin, hair, glands, nails, and sensory receptors
Covers the external surface of the body
INTEGUMENTARY SYSTEM VS ANY OTHER SYSTEMS
The appearance of our skin frequently determines
the initial impression we
make on others.
SKIN AS AN ORGAN
Largest organ of the body
7,600 sq cm (3,000 sq in) adult
Approximately 7% body weight
Thickness: 1.5 mm (average)
Thickest: 6 mm (soles and palms)
Thinnest: 0.5 mm (eyelids, external genitalia, ear drum)
Texture
Rough or callous: elbows and knuckles
Soft and sensitive: eyelids
LAYERS OF SKIN
Two Main Parts Epidermis epithelial tissue
Dermis connective tissue
Hypodermis subcutaneous layer; not part of the skin;
areolar and adipose tissue
Storage depot for fat
Contains blood vessels
Contain nerve endings
EPIDERMIS
Superficial protective layer
Derived from ectoderm
Stratified squamous epithelium
All but the deepest layers are composed of dead
cells.
Keratinization new cells (with keratin) push old cells
to surface
EPIDERMIS
Keratinocytes (90%) Arranged in 4 or 5 layers
Keratin tough fibrous protein
Resemble flat dead scales
Melanocytes (8%) Melanin skin color;
protection against UV
light
Genetically inherited
EPIDERMIS
Merkel cells Sensory receptor
cells
Consist of tactile disc and neuron
Tactile (touch) reception
Langerhans cells Immune responses
Macrophage
Ingest bacteria
EPIDERMIS
EPIDERMIS
Stratum basale Basal layer
Deepest; attached to dermis
single row of cuboidal or columnar keratinocytes
Stratum spinosum Spiny layer
8-10 layers of many-sided keratinocytes
Spiny extensions of cells
Strength and flexibility
EPIDERMIS
Stratum granulosum Granular layer
3-4 flattened rows of cells
Keratohyalin chemical precursor to keratin
Stratum lucidum Clear layer
Nuclei, organelles, cell membrane not visible
Lips, soles and palms
EPIDERMIS
Stratum corneum Horn-like layer
25-30 layers flattened, scale-like cells
Protects the skin
Protective adaptation: drying and flattening
Friction stimulates additional mitotic activity in basale and
spinosum: callus
Dandruff: flaking off scalp
EPIDERMIS
SKIN COLORATION
Melanin
Brown-black pigment
Variations: production and distribution
Protects basal layer against UV
Tanning increased production
Albinism
Normal number of cells
Lacks tyrosinase (tyrosine to melanin)
Hereditary
Freckles aggregated patches of melanin
SKIN COLORATION
Vitiligo
White spots
Lack of cells in local areas
Liver spots
Exposed portions
Brown, plaque-like growths
Benign growths of cells
Carotene
Yellowish pigment
Plant products
Accumulates in corneum and dermis
DERMIS
Dense connective tissue: collagen and
elastic fibers
Cleavage lines: where skin is most resistant to
stretching
fibroblasts, nerve endings, smooth
muscle, glands, blood
vessels, and hair
follicles
DERMIS
DERMIS
Papillary Layer
Thin connective tissue
Areolar with elastic
Contains blood vessels
Dermal Papillae
Projections that extend to epidermis
Waste removal and temperature
regulation
Ridged on hands and feet
Genetically determined
DERMIS
Reticular Layer
Deepest
80% of dermis
More dense and regularly arranged
Dense collagenous
Tough, flexible meshwork
tearing
Stretch marks
HYPODERMIS
Adipose tissue
Heat insulator and fat storage
Amount varies
Loose connective tissue
Allows skin to be bound with muscles
Large blood vessels
Arteries and veins
ACCESSORY STRUCTURES OF THE SKIN
HAI R, SK I N GLANDS AND NAI LS
HAIR
Protection
Scalp, nostrils, brows, external
genitalia
Thread of fused, dead, keratinized
epidermal cells
Shaft superficial
Root into the dermis
HAIR
Hair follicle
External and internal root sheaths
Hair bulb
Papilla contains blood vessels;
nourishment
Matrix produces new hair; cell division
Smooth muscle
Goosebumps
HAIR
HAIR OR PILI
Melanin synthesized by melanocytes in the matrix of the bulb
Dark-colored brown to black melanin
Blonde and red yellow to red melanin Iron and more sulfur
Gray decline melanin synthesis
White accumulation of air bubbles in the hair shaft
Hirsutism excessive body hair androgens
Androgenic alopecia Male-pattern baldness
HAIR
GLANDS
Single or groups of epithelial cells that
secrete a substance
Sebaceous Glands
Sudoriferous Glands Eccrine sweat glands
Apocrine sweat glands
Ceruminous Glands
SUDORIFEROUS GLANDS
Sweat glands
Release sweat, or perspiration into
hair follicles, onto
the skin surface
(pores)
Eccrine more common
Apocrine simple, coiled tubular Odorless; bacteria
(body odor)
SUDORIFEROUS GLANDS
FEATURES ECCRINE GLAND APOCRINE GLAND
Distribution Widely distributed
(forehead, palms, soles)
Axilla, groin, areolae,
bearded regions of the face
Secretory portion Dermis Hypodermis
Excretory portion Epidermis Hair follicle
Nature of secretion Water, ions, urea, uric
acid, amino acid,
glucose, lactic acid
Slightly viscous, milky or
yellowish; lipids and proteins
Function Regulates body
temperature
Emotional stress and sexual
excitement; cold sweat
Onset of function After birth During puberty
SEBACEOUS GLANDS
Oil glands
Increases during adolescence
Connected to hair follicles
Secreting portions dermis
None in the palms and soles
Secrete sebum Keeps hair from drying out
Prevents excessive evaporation of water from the skin
Keeps the skin soft
Inhibits growth of certain bacteria
SEBACEOUS GLANDS
Blackheads enlarged glands in the face Color due to melanin and
oxidized oil, not dirt
Pimples or boils sebum is nutritive to bacteria
Acne inflammation of glands
CERUMINOUS GLANDS
External auditory canal
Cerumen secretion of ceruminous and
sebaceous Earwax
Plus hairs of the external auditory canal sticky barrier
Waterproofs the canal
Prevents bacteria and fungi from entering
NAILS
Plates of tightly packed, hard, dead,
keratinized cells of
epidermis
Grasp and manipulate small objects
Provide protection to the ends of fingers and
toes
Allows to scratch various parts of the
body
NAILS
Nail body visible Pink blood capillaries
Free edge extends past the end of the
finger or toe
Nail root Lunula whitish (vascular
tissue) semilunar area near
the nail root
Nail matrix superficial cells divide by mitosis Average growth of nails 1
mm (0.04 in) per week
Cuticle stratum corneum
NAILS
FUNCTIONS OF THE SKIN
Regulates body temperature Sweating promotes evaporation
High temperature
Increased sweat (lowers body temperature)
Vasodilation larger surface area in blood vessels
Low temperature
Decreased sweat (conserves heat)
Vasoconstriction smaller surface area in blood vessels
FUNCTIONS OF THE SKIN
Protection Chemical Factors
Oily sebum prevents hair from drying
Acidic pH of perspiration retards growth of microbes
Sweat is slightly hypertonic flush off bacteria
Melanin protection against UV light
FUNCTIONS OF THE SKIN
Protection Physical Factors
Stratified squamous epithelium prevents bacteria invasion
Keratinized cells physical barrier against invasion
Biological Factor
Macrophage destroy bacteria and foreign
substances
FUNCTIONS OF THE SKIN
Excretion Ammonia, urea, and excessive
salt
Sweating
Absorption Oxygen and carbon dioxide
Small amounts of UV light
FUNCTIONS OF THE SKIN
Cutaneous sensations Arise in the skin
Receptors for:
Pain free nerve endings
Temperature hot and cold receptors
Touch Merkels disks and Meissners corpuscles
Pressure Pacinian corpuscles
FUNCTIONS OF THE SKIN
Synthesis of Vitamin D Exposure of skin to UV light
activates Vitamin D
Vitamin D is converted to calcitriol (active hormone)
in the liver and kidney
Metabolism of calcium and phosphorus
AS A DIAGNOSTIC TOOL
Cyanosis
Jaundice
Rashes and lesions
Condition of skin, hair, and nails
Vitamin A deficiency sandpaper texture of the skin
Iron deficiency anemia spoon-shaped nails
AGING AND THE INTEGUMENTARY SYSTEM
1. Collagen fibers (dermis) Decrease in number, stiffen, break
apart, disorganize
2. Elastic fibers
Lose elasticity, thicken
3. Fibroblasts (produce collagen
& elastic fibers)
Decrease in number
Wrinkles
4. Langerhans cells and
macrophages Decrease in number; less-efficient
phagocytes
5. Sebaceous glands Decrease size leads to dry and
broken skin; susceptible to infection
AGING AND THE INTEGUMENTARY SYSTEM
1. Production of sweat diminishes; heat stroke
2. Melanocytes Decreasing in number; gray hair;
increasing in size (age spots)
3. Hair follicles stop producing hairs; hair loss
4. Walls of blood vessels (dermis)
thicker, less permeable, lost adipose tissue
5. Migration of cells from basal to
epidermal is slow skin heals poorly
AGING AND THE INTEGUMENTARY SYSTEM
Study the integumentary system
and prepare for a quiz.
mdop/7.1.13