INTEGUMEN

TARY

SYSTEM

THE INTEGUMENT

Is the largest system of the body 16% of body weight, 1.5 to 2m2 in area, The integument is made up of two parts:

1. Cutaneous membranea. Epidermis– Superficial epitheliumb. Dermis – underlying CT with blood

supply2. Accessory structures

a. Hairb. Nailsc. Exocrine Glands

PROTECT ION First line of defense

against Bacteria Viruses

Protects underlying structures from Ultraviolet (UV)

radiation Dehydration

BODY TEMPERATURE REGULAT ION

If too hotDermal blood vessels dilateVessels carry more blood to surface so heat can escape

If too coldDermal blood vessels constrict

Prevents heat from escaping

Functions of the Integumentary

System

EXCRET ION Small amounts of

waste products are lost through perspiration

VITAMIN D PRODUCTION

Needed for calcium absorption

Functions of the Integumentary

System

SENSATION Sensory receptors

STRUCTU

RE OF S

KIN

Epidermis

Dermis

Hypodermis or

subcutaneous layer

SKIN STRUCTURE : EPIDERMIS The Epidermis

Is a vascular stratified squamous epithelium Nutrients and oxygen diffuse from capillaries in the dermis

Cells of the Epidermis Keratinocytes

Arise from deepest layer of epidermis to stratum spinosum Produce keratin, antibodies and enzymes

Melanocytes Found in basal layer, manufacture and secrete pigment

Merkel cells Found in basal layer, attached to sensory nerve endings

Langerhans cells Found in stratum spinosum, part of immune system

macrophage-like

Structures of the Epidermis The five strata of keratinocytes in

thick skin From basal lamina to free surface

1. Stratum basale2. Stratum spinosum3. Stratum granulosum4. Stratum lucidum5. Stratum corneum

SKIN STRUCTURE : EPIDERMIS

SKIN STRUCTURE : DERMIS

Hair

Papillarylayer

Reticularlayer

Cutaneousplexus

Papillaryplexus

Epidermalridges

Dermalpapillae

Capillary loopof papillary

plexusDERMIS

SKIN STRUCTURE : DERMIS Second major layer of the skin Provides mechanical strength, flexibility, and protection for underlying

tissues Highly vascular and contains a variety of sensory receptors that provide

information about the external environment Has two layers

The papillary layer The reticular layer

Flexure lines - creases on palms

THE PAPILLARRY LAYER

• Underlies epidermis• Named for dermal papillae• Aerolar connective tissue• Supports, nourishes epidermis• Provides sensory nerves,

lymphatics, and capillaries

THE RETICULAR LAYER

• Tough, dense, fibrous layer• Dense irregular connective

tissue• Collagen fibers - limit stretch• Elastic fibers - provide flexibility• Blends into papillary layer

(above)• Blends into subcutaneous layer

(below)

The Hypodermis (Subcutaneous Layer)Lies below the integumentStabilizes the skinAllows separate movement Made of elastic areolar and adipose tissuesConnected to the reticular layer of integument by connective

tissue fibers Deposits of Subcutaneous FatDistribution patterns determined by hormonesReduced by cosmetic liposuction (lipoplasty)

SKIN STRUCTURE : HYPODERMIS

STRUCTU

RE OF H

AIR

T H E H A I R F O L L I C L E

Hair follicles are the organs that form the hairs.

Located deep in dermis.Produces nonliving hairs. Wrapped in a dense connective

tissue sheath.Base is surrounded by sensory

nerves (root hair plexus). Control bacteria

A C C E SS O RY S T R U C T U R E S O F

H A I RArrector pili

Involuntary smooth muscle

Causes hairs to stand upProduces “goose bumps”

Sebaceous glands Lubricate the hair Exposed

shaftof hair

Sebaceousgland

ArrectorpilimuscleConnectivetissue sheath

Root hairplexus

R E G I O N S O F H A I RHair root

Lower part of the hairAttached to the

integumentHair shaft

Upper part of the hairNot attached to the

integument

Boundary betweenhair shaftandhair root

Hair shaft

SebaceousglandArrectorpili muscle

Hair root

Connectivetissue sheathHair bulbHair matrixHair papilla

HAIR FUNCTION

Head: UV protectionCushion from traumaInsulation

Nostrils, Ear canals, Eyelashes:Prevent entry of foreign material

Body Hair: Sensory detection

Root hair plexus:Sensory nerves at base of hair follicle that detect slight

movement of hairArrector pili muscle:

Attached to every hair follicleContract to stand hair perpendicular to skin surface

STRUCTU

RE AND

FUNCTIO

N OF NAILFree edge

of Nail

Body of Nail

Laternal Nail fold

Lunula

Eponychium (cuticle)

STRUCTURE AND FUNCTION OF NAIL Nails

Protect fingers and toesMade of dead cells packed with keratin Metabolic disorders can change nail structure

Nail Production

Occurs in a deep epidermal fold near the bone called the nail root

Structure of a NailNail body

The visible portion of the nailCovers the nail bed

LunulaThe pale crescent at the base of the

nailSides of nails

Lie in lateral nail grooves Surrounded by lateral nail folds

A longitudinal section

EponychiumProximal nail fold

Nail root

Lunula Nail body

Epidermis Dermis Phalanx Hyponychium

STRUCTURE AND FUNCTION OF NAIL