a large amount of the dust in you home is actually dead skin. humans shed about 600,000 particles of...

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?

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

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

Artery

VeinCutaneousplexus

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

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

FUNCTIONS OF EPITHELIA (4-2)

Provide physical protection

Control permeability

Provide sensation

Produce specialized secretions (glandular

epithelium) Exocrine glands

Endocrine glands

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

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

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

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

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

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

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

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

Microvilli

Apicalsurface

Golgiapparatus

Nucleus

Mitochondria

Basement membrane

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.

Surface

Stratumcorneum

Stratumlucidum

Stratumgranulosum

Stratumspinosum

Stratum basale

Basementmembrane

Dermis

Thick skin LM x 210

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

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

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

Melanocytesin stratumbasale

Melaninpigment

Basementmembrane

LM x 600Melanocytes

Melanosome

MelaninpigmentMelanocyte

Basementmembrane

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)

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

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

Basal cell carcinoma Melanoma

Christmas

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

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

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

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

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

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

Hair matrix grows, making hair longer, and

cells become keratinized and die

Halfway to skin surface, it becomes the hair

Above the surface it is called the hair shaft

Shaft has three layers of dead cells

From outer to inner: cuticle, cortex, and medulla

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

Sebaceous gland

Hair shaft

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.

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

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

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

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

SWEAT GLANDS (5-7)

Also called sudoriferous glands

Include two types

1. Apocrine sweat glands

2. Merocrine sweat glands

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

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

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

Nail root Where the nail is produced

Covered by the cuticle

Lunula Pale crescent near root

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.

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

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

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

Epidermis

Dermis

Mast cells

Migratingepithelialcells

Macrophagesand fibroblasts

Granulationtissue

Fibroblasts

Scartissue

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

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)

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

Muscles become weaker and bone strength

decreases

Due to a decline in vitamin D3

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

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

a large amount of the dust in you home is actually dead skin. humans shed about 600,000 particles of...

skin cells

layers of skin

protection skin

pounds of skin

light skin

dark skin

dead skin

particles of skin

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