Integumentary SystemIntegumentary System

Consists of Consists of skinskin hair hair glandsglands nailsnails

Largest organ of the Largest organ of the human body the human body the

Skin accounts for 16% Skin accounts for 16% of the bodies mass!of the bodies mass!

FunctionsFunctions1.1. Protection—first Protection—first

line of defenseline of defense Disease Disease (micro-invaders)(micro-invaders)

Loss of fluidsLoss of fluids Physical injuryPhysical injury UV LightUV Light

2.2. Regulation of Regulation of TempTemp

SweatSweat InsulationInsulation Blood supplyBlood supply

3.3. CommunicationCommunication ReceptorsReceptors

Hot/coldHot/cold PainPain TouchTouch

4.4. Vitamin D Vitamin D ProductionProduction

Calcium absorptionCalcium absorption For bonesFor bones For muscle For muscle

contractioncontraction

5.5. Excretion of Excretion of WastesWastes

sweatsweat

FunctionsFunctions

Subcutaneous(Hypodermis)

Dermis

Epidermis

Dermis

Skin Cross Section

Epiderm

is

The epidermis is divided into two layers, dead and living cells.

Dead

Living

Living cells of the epidermis replicate, Living cells of the epidermis replicate, pushing their way towards the surface.pushing their way towards the surface.

The cells flatten and the organelles The cells flatten and the organelles disintegrate.disintegrate.

Eventually the living cells of the Eventually the living cells of the inner epidermis become the dead, inner epidermis become the dead, tough, waterproof, and flexible tough, waterproof, and flexible outer layer.outer layer.

As the living cells replicate they As the living cells replicate they produce produce

keratinkeratin and and melaninmelanin..

KeratinKeratin tough tough fibrous proteinfibrous protein

for for strengthstrength and a and a waterproofwaterproof texture. texture.

MelaninMelanin dark brown dark brown pigmentpigment

accounts for the variations in accounts for the variations in skin colorskin color..

Dermis•blood vessels• nerve endings •glands •sense organs •smooth muscles• hair follicles.

Epidermis

Skin Cross Section

Subcutaneous tissueSubcutaneous tissue Layer of fatLayer of fat

InsulationInsulation

Food reserveFood reserve

Two major types 1. Sweat glands Eccrine- thin and watery Apocrine- thick, kicks in

at puberty

2. Sebaceous glands Sebum- an oil that

coats the surface of the skin flexibility and

waterproofing

Hair Follicle

• Nails grow rapidly from the nail root.

• During cell division the nail root fills with keratin producing a plate-like nail.

• Fingernails grow 4 times faster than toe nails with an average rate of 3 millimeters per month.

Functions of Integumentary Functions of Integumentary system.system.

The layers of the skin.The layers of the skin.

Various components of the Various components of the epidermis and dermis, epidermis and dermis, including the nails.including the nails.