Integumentary System

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 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

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

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


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


Protection Physical Factors

Stratified squamous epithelium prevents bacteria invasion

Keratinized cells physical barrier against invasion

Biological Factor

Macrophage destroy bacteria and foreign

substances


Excretion Ammonia, urea, and excessive

salt

Sweating

Absorption Oxygen and carbon dioxide

Small amounts of UV light


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


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


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

Study the integumentary system

and prepare for a quiz.

mdop/7.1.13

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Integumentary System