Integumentary System

Integumentary system consists of skin and its accessory organs

Accessory organs:Hair folliclesNailsSkin glands

Skin - is the body’s outmost covering and its largest organ.

Introduction

Functions of SkinProtection

Bacteria VirusesUltraviolet (UV) radiation

Dehydration

Body temperature regulationIf too hot

Dermal blood vessels dilateVessels carry more blood to surface so heat can escape

If too coldDermal blood vessels constrictPrevents heat from escaping

Vitamin D productionNeeded for calcium absorption

SensationSensory receptors

ExcretionSmall amounts of waste products are lost through perspiration

Structure of skin

Epidermis

Dermis

Hypodermis or subcutaneous layer

Epidermis - the outmost layer of skin. Dermis - the innermost layer of the skin. hypodermis - beneath the dermis.

Layers of Skin:

EpidermisThe most

superficial layer. • Stratum

Corneum• Stratum Basale

(stratum germinativum)

Two parts:Stratum corneum

Outermost layerMostly dead cells form an

impermeable layerStratum basale (stratum germinativum)Deepest layerCells constantly dividing and pushing

older cells outward

Epidermis

Keratinocytes - most common cell of epidermis. - makes and accumulates keratin - provides protection and waterproofing sealant.Melanocyte

- makes the pigment melanin. - produces and transfer the protein melanin to keratinocytes.

Specialized types of cells

Skin Color:Determined by

amount of melanin in the epidermis of skin

The more melanin, the darker the skin colorRange is from

yellowish to brownish

Structure of Skin