Chapter 5: Chapter 5: The Integumentary The Integumentary

SystemSystem

What are the structures What are the structures and functions of the and functions of the

integumentary system?integumentary system?

Size of the IntegumentSize of the Integument

The The integumentintegument is the largest system of is the largest system of the body:the body: 16% of body weight16% of body weight 1.5 to 2 m1.5 to 2 m22 in area in area

Parts of the IntegumentParts of the Integument

The integument is made up of The integument is made up of

2 parts:2 parts:1.1. cutaneous membranecutaneous membrane (skin) (skin)

2.2. accessory structuresaccessory structures

Parts of the Parts of the Integumentary SystemIntegumentary System

Parts of the Parts of the Cutaneous MembraneCutaneous Membrane

Outer Outer epidermisepidermis:: superficial epithelium (epithelial tissues)superficial epithelium (epithelial tissues)

Inner Inner dermisdermis:: connective tissuesconnective tissues

Accessory StructuresAccessory Structures

Originate in the dermisOriginate in the dermis Extend through the epidermis to skin Extend through the epidermis to skin

surface:surface: hairhair nailsnails multicellular exocrine glandsmulticellular exocrine glands

ConnectionsConnections

Circulatory system:Circulatory system: blood vessels in the dermisblood vessels in the dermis

Nervous system:Nervous system: sensory receptors for pain, touch, and sensory receptors for pain, touch, and

temperaturetemperature

The Subcutaneous LayerThe Subcutaneous Layer

Subcutaneous layerSubcutaneous layer (superficial fascia or (superficial fascia or hypodermis)hypodermis): : loose connective tissueloose connective tissue below the dermis below the dermis location of hypodermic injectionslocation of hypodermic injections

Functions of SkinFunctions of Skin

ProtectsProtects underlying tissues and organs underlying tissues and organs ExcretesExcretes salts, water, and organic wastes salts, water, and organic wastes

(glands)(glands) MaintainsMaintains body temperature (insulation body temperature (insulation

and evaporation)and evaporation)

Functions of SkinFunctions of Skin

SynthesizesSynthesizes vitamin D vitamin D33

StoresStores lipids lipids DetectsDetects touch, pressure, pain, and touch, pressure, pain, and

temperaturetemperature

What are the main structures and functions of the epidermis?

Cells of the EpidermisCells of the Epidermis

KeratinocytesKeratinocytes:: contain large amounts of keratincontain large amounts of keratin the most abundant cells in the epidermisthe most abundant cells in the epidermis

EpidermisEpidermis

Avascular stratified squamous epitheliumAvascular stratified squamous epithelium Nutrients and oxygen diffuse from Nutrients and oxygen diffuse from

capillaries in the dermiscapillaries in the dermis

Thin SkinThin Skin

Covers most of the body Covers most of the body Has 4 layers of keratinocytesHas 4 layers of keratinocytes

Layer of skinLayer of skin

Stratum germinativumStratum germinativum Epidermal ridges Epidermal ridges

Page 156Page 156

Stratum spinosumStratum spinosum Spiny layersSpiny layers

P 156P 156

Stratum granulosumStratum granulosum Grainy layer Grainy layer

5 layers of skin only5 layers of skin only

Stratum lucidumStratum lucidum Only in palms and soles Only in palms and soles

p156p156

Stratum corneumStratum corneum DeadDead

• 15 – 30 cell layers15 – 30 cell layers• Water resistant – not waterproofWater resistant – not waterproof

Thick SkinThick Skin

Covers the palms of the hands and soles Covers the palms of the hands and soles of the feetof the feet

Has 5 layers of keratinocytesHas 5 layers of keratinocytes

Skin Life CycleSkin Life Cycle

It takes 15–30 days for a cell to move It takes 15–30 days for a cell to move from from stratum germinosumstratum germinosum to to stratum stratum corneumcorneum

What causes different skin colors?

Skin ColorSkin Color

Skin color depends on:Skin color depends on: the pigments the pigments carotenecarotene and and melaninmelanin blood circulation (red cells)blood circulation (red cells)

CaroteneCarotene

Orange-yellow pigmentOrange-yellow pigment Found in orange vegetablesFound in orange vegetables Accumulates in epidermal cells and fatty Accumulates in epidermal cells and fatty

tissues of the dermistissues of the dermis Can be converted to vitamin ACan be converted to vitamin A

MelaninMelanin

Yellow-brown or black pigmentYellow-brown or black pigment Produced by Produced by melanocytesmelanocytes in stratum in stratum

germinativumgerminativum Stored in transport vesicles Stored in transport vesicles

((melanosomesmelanosomes)) Transferred to keratinocytesTransferred to keratinocytes

Function of MelanocytesFunction of Melanocytes

Melanin protects skin from sun damageMelanin protects skin from sun damage Ultraviolet (UV) radiationUltraviolet (UV) radiation::

causes DNA mutations and burns which lead causes DNA mutations and burns which lead to cancer and wrinklesto cancer and wrinkles

MelanocytesMelanocytes

Skin color depends on melanin production, Skin color depends on melanin production, not number of melanocytesnot number of melanocytes

Capillaries and Skin ColorCapillaries and Skin Color

Oxygenated red blood contributes to skin Oxygenated red blood contributes to skin color: color: blood vessels dilate from heat, skin reddensblood vessels dilate from heat, skin reddens blood flow decreases, skin palesblood flow decreases, skin pales

CyanosisCyanosis

Bluish skin tintBluish skin tint Caused by severe reduction in blood flow Caused by severe reduction in blood flow

or oxygenationor oxygenation

Illness and Skin ColorIllness and Skin Color

JaundiceJaundice:: buildup of bile produced by liverbuildup of bile produced by liver yellow coloryellow color

Addison’s diseaseAddison’s disease:: and other diseases of and other diseases of pituitary glandpituitary gland skin darkeningskin darkening

What are the structures and What are the structures and functions of the dermis?functions of the dermis?

The The DermisDermis

Is located between epidermis and Is located between epidermis and subcutaneous layersubcutaneous layer

Anchors epidermal accessory structures Anchors epidermal accessory structures (hair follicles, sweat glands) (hair follicles, sweat glands)

Characteristics of DermisCharacteristics of Dermis

Strong, due to collagen fibersStrong, due to collagen fibers Elastic, due to elastic fibersElastic, due to elastic fibers Flexible (Flexible (skin turgorskin turgor))

Skin DamageSkin Damage

Sagging and wrinkles (reduced skin Sagging and wrinkles (reduced skin elasticity) are caused by:elasticity) are caused by: dehydrationdehydration ageage hormonal changeshormonal changes UV exposure UV exposure

Lines of CleavageLines of Cleavage

Collagen and elastic fibers in the dermis: Collagen and elastic fibers in the dermis: are arranged in parallel bundlesare arranged in parallel bundles resist force in a specific directionresist force in a specific direction

Clinical ImportanceClinical Importance

Lines of cleavageLines of cleavage establish important establish important patterns:patterns: a parallel cut remains shut, heals wella parallel cut remains shut, heals well a cut across (right angle) pulls open and scars a cut across (right angle) pulls open and scars

Lines of CleavageLines of Cleavage

Dermal CirculationDermal Circulation

What are the structures What are the structures and functions of the and functions of the subcutaneous layer?subcutaneous layer?

The HypodermisThe Hypodermis

The The subcutaneous layersubcutaneous layer or or hypodermishypodermis: : lies below the integumentlies below the integument stabilizes the skinstabilizes the skin allows separate movementallows separate movement

What are the skin glands What are the skin glands and secretions?and secretions?

Exocrine GlandsExocrine Glands

Sebaceous glandsSebaceous glands (oil glands): (oil glands): holocrine glandsholocrine glands secrete secrete sebumsebum

Sweat glandsSweat glands:: merocrine glandsmerocrine glands watery secretionswatery secretions

Types of Sebaceous GlandsTypes of Sebaceous Glands

Simple branched alveolar glandsSimple branched alveolar glands:: associated with hair follicles associated with hair follicles

Sebaceous folliclesSebaceous follicles:: discharge directly onto skin surfacedischarge directly onto skin surface

Sebaceous GlandsSebaceous Glands

SebumSebum

Contains lipids and other ingredientsContains lipids and other ingredients Lubricates and protects the epidermisLubricates and protects the epidermis Inhibits bacteriaInhibits bacteria

What are the functions of sweat glands?

Types of Sweat GlandsTypes of Sweat Glands

ApocrineApocrine:: found in armpits, around nipples, and groinfound in armpits, around nipples, and groin

MerocrineMerocrine:: widely distributed on body surfacewidely distributed on body surface especially on palms and solesespecially on palms and soles

Apocrine Sweat GlandsApocrine Sweat Glands

Merocrine secretions, not apocrineMerocrine secretions, not apocrine Associated with hair folliclesAssociated with hair follicles Produce sticky, cloudy secretions Produce sticky, cloudy secretions Break down and cause odorsBreak down and cause odors

Merocrine Sweat GlandsMerocrine Sweat Glands

Also called Also called eccrine glandseccrine glands:: coiled, tubular glandscoiled, tubular glands discharge directly onto skin surfacedischarge directly onto skin surface sensible perspirationsensible perspiration water, salts, and organic compoundswater, salts, and organic compounds

Functions of Merocrine SweatFunctions of Merocrine Sweat

Cools skinCools skin Excretes water and electrolytesExcretes water and electrolytes Flushes microorganisms and harmful Flushes microorganisms and harmful

chemicals from skinchemicals from skin