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CHAPTER 5The Integumentary System

Copyright © 2007 by John Wiley & Sons, Inc.

Principles ofHuman Anatomy

Eleventh Edition

Principles ofHuman Anatomy

Eleventh EditionGerard J. Tortora

&

Mark T. Nielsen

Integumentary SystemIntegumentary System

n Skin and accessory organsn Hair, nails, glands, muscles, nerves

n Dermatology n Medical specialty the deals w/ skin disorders

n Anatomy: 2 major layersn Epidermisn Dermis

n Subcutaneous layer is not part of the skin

05_01a05_01a Cells of the EpidermisCells of the Epidermisn Keratinocytes

n 90% of epidermal cellsn Produce keratin

n Protects from light heat & bacteria

n Melanocytesn 8% of cellsn Produce melanin

n Protects against UV light

n Langerhan’s cellsn Immune response

n Merkel cellsn Touch sensation

Layers of the EpidermisLayers of the Epidermis DermisDermis

n Composed of connective tissuen Areolar – Papillary Regionn Dense irregular - Reticular Region

n Fibroblasts, macrophages adipocytesn Blood vessels, nerves, glands, hair folliclesn Thick in palms & soles/Thin in eyelids, penis &

scrotumn Thicker-posterior body and lateral limbs/Thinner-

anterior body and medial limbs

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Layers of the DermisLayers of the Dermis 05_01bc05_01bc

Increase the grip of the hand or foot

Sweat glands open at the top of the ridge

Produce fingerprints or footprints

Dermatoglyphics is the study of epidermal ridge patterns

Lines of CleavageLines of Cleavagen Indicate the main

direction of collagen fibers in reticular region

n Important in surgery esp. plastic surgery

n Incisions parallel to these lines heal with fine scars

n Incisions made across these lines make broad thick scars

Subcutaneous LayerSubcutaneous Layer

n Not actually a layer of the skin!n Also called:

n Sub-Qn Superficial fascian Hypodermis

n Areolar CT and adipose tissuen Contains Pacinian corpuscles

n Pressure sensors

Functions of the SkinFunctions of the Skinn Regulation of body temperature

(Thermoregulation)n Changes in blood flow to the skinn Sweating by sudoriferous glands

n Protectionn Physical barrier to the external environment

n Abrasion, bacteria, dehydration, UV lightn Sensation

n nerve ending/receptors/sensorsn Touch – Merkel or Meisner’sn Pressure – Pacinian corpusclesn Temperaturen Pain - nocoception

Functions of the Skin cont.Functions of the Skin cont.n Excretion

n Lactic acid, urea, ions (K+) in sweatn Immunity

n Langerhan’s cells n Blood reservoir

n Regulated by vasoconstriction & vasodilation of arterioles

n Synthesis of Vitamin Dn UV lightn Vitamin D is considered a hormone

n Absorption of Ca++

n Skin is an endocrine organ

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Skin ColorSkin Colorn 3 major pigments

n Melaninn Pale yellow to blackn Produced by melanocytes

nn About the same # in all racesAbout the same # in all racesnn Amount of melanin secretion is differentAmount of melanin secretion is different

n More melanocytes in areola, penis, face, limbsn Cause freckles, liver/age spotsn Synthesis of melanin increases with UV exposuren Protectiven Lack of melanin - albinism

Skin ColorSkin Color

n 3 major pigments (cont.)n Carotene

n Yellow to orangen Precursor to Vitamin An Found in carrots, egg yolk, yellow/orange fruits

n Hemoglobinn Pigment in RBCs that carries O2

n Red when oxygenated n Blue when deoxygenated

Accessory organs of the SkinAccessory organs of the Skinn Hairn Glandsn Nails

Hair AnatomyHair Anatomyn Shaft (Part that you can see)n Root (Part you can’t see)n 3 layers

n Medullan Cortexn Cuticle

n Hair folliclen Surrounds the rootn 2 layersn Internal & external root sheaths

n Extensions of the epidermis

n Bulb arean Papillae of the hairn Matrix of the hair

n Derived form the stratum basale

05_05e05_05e Hair GrowthHair Growth

n 2 stagesn Growth

n Cells dividing in the matrix making hair longern About 3 years in the scalp

n Resting n No new cellsn 1-2 years

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Hair ColorHair Color

n Melaninn Melanocytes located in the matrix of the bulbn Dark hair – true melaninn Blond hair – melanin variant containing sulfurn Red hair – melanin variant containing iron

Structures assoc. w/ HairStructures assoc. w/ Hair

n Arrector pili musclen Smooth musclen Contract in response

to cold or fearn Hair root plexuses

n Light touch receptorsn Sabaceous (oil)

glands

Hair root plexus

Arrector pilimuscle

GlandsGlandsn Sabaceous (oil) glands

n Secrete onto hair or skin surface

n Sudoriferous (sweat) glandsn 2 types eccrine and

apocrinen Ceruminous Glands

n Produce cerumen = “ear wax”

Eccrine & Apocrine Sweat GlandsEccrine & Apocrine Sweat Glands

NailsNails Nail FactsNail Facts

n Grow about 1mm per weekn Toe nails grow slower

n It takes approx. 8 mo. for a toenail to grow out

n Longer digits have faster growing nailsn Nails grow faster in warmer monthsn Function to aid in grasping and scratchingn As long as you have no diet deficiencies,

taking gelatin doesn’t help growth of nails.

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Thin vs. Thick SkinThin vs. Thick Skin Learning ObjectivesLearning Objectivesn Discuss the general features (layers/organs) of the

skinn Describe the major cell types in the skinn Discuss the function of keratinn Know in detail the descriptions of the layers of the

epidermis n Describe the layers of the dermis in terms of the

tissues and organs present n What causes fingerprints?n Know the major functions of the skinn Know the pigments responsible for skin colorn Discuss the different sensory receptors present and

what they are designed to sense

Learning ObjectivesLearning Objectivesn Describe the anatomy of a hair and is

folliclen Discuss the 3 structures associated with

hair n What are the grow stages of hairn Discuss the different exocrine glands in

the skin and their secretionsn What are the differences between

apocrine and eccrine glands

Learning ObjectivesLearning Objectives

n Describe the major parts of a nailn What layer of the skin do hair and nails

grow from?n Discuss some factors that effect nail

growthn Discuss the ‘lines of cleavage’ and why

they are clinically important