The Integumentary System

Chapter 4

Integumentary System

Structure EpidermisDermisSubcutaneous

Functions of the skin

The “Birthday Suit”Combination of 4 main

tissuesEpithelial – outer layerConnective – underlies & connects dermisSmooth Muscle – erect hairNervous – sensory receptors

Structure allows it to carry out many functionsProtection, hydration, sensation, color, temperature regulation, etc.

Very durable

Functions of the Skin

ProtectionTemperature regulation

SensationsStorage of chemical compounds

Excretion of wastes

Synthesis of compounds

Determines characteristics

Structure of the Skin2

principal partsEpidermisDermis

Beneath the DermisSubcutaneous

EpidermisStratified squamous epithelium

Approximately every month we shed entire skin surface

Consists of keratinocytes

Layers of the Epidermis (bottom to top)

Stratum Germinativum Cuboidal cells Mitosis occurs

Stratum Spinosum Germinal cells shrink

Cells look spiny

Stratum Granulosum Produces keratohyaline & keratin

Cells die

Stratum Lucidum Found only in thick skinned or calyces areas (hands, feet, elbows, knees)

“Clear layer” Filled with keratin

Stratum Corneum Multiple dead layers

“Cornified” Waterproof

Layers of the Epidermis

Variations in Skin Color

Pigments Melanin

Produced by melanocytesProtects skin from UV rays

CaroteneRed pigment of “gingers”

Lack of pigment

Albino

Dermal blood supply “Blushing”

Epidermis & Dermis

Epidermis is avascular (contains no vessels)

Dermis is highly vascular (contains blood vessels)

Epidermis receives nourishment from dermis

Cells furthest away from nourishment die

Dermal Layer2 layers

Papillary layer Reticular layer

Connective tissue

Loose Fibrous (collagen firm & elastic)

Adipose

Contains Blood vessels Nerves Glands Hair follicles

Papillary LayerMost superficial layer

Loose connective tissue

Surface area increased by papillae Form fingerprints for grip

Reticular LayerDeeper layerDense, irregular connective tissue (collagen)

Contains Blood vessels Glands Deep pressure receptors

Subcutaneous LayerLoose connective

tissuePacked with adipocytes (fat cells)

Stabilizes position of skin, shock absorber, energy storage/source

Epidermal Appendages

HairGlandsNails

Hair (Pili)Came with mammalsEmbryological development & distribution

Life span of hairWhat does hair do for mammals?

Functions of Hair

ProtectionThermoregulationSensoryMinor? role in humans

beauty

Hair Structure

ShaftSuperficial

RootBelow surface

Hair StructureMedulla

Soft core

CortexHard core

Gives hair stiffness

CuticleOutermost layer

Hair Develops in Follicles

Location Deep in dermis

Structure External root sheath

Internal root sheath

BulbContains matrix

Hair papillaContains blood vessels and nerves

http://www.tgfolk.net/sites/gtg/tfb-elect.html

Arrector PiliSmooth muscle attaches to follicle

Raises hairsEmotional response, cold

Function- traps air

GlandsSebaceous glands

Connected to hair folliclesSecrete a waxy, oily substance (sebum)

Develop in utero at about 5 months

Secretion increases at puberty

GlandsSweat glandsEccrine glandsFound just about everywhere (esp. palms & soles)

Produce “perspiration”Water, salt, met. wastes

http://www.pg.com/science/skincare/Skin_tws_35.htm

GlandsSweat glands (scent glands)Called Apocrine sweat glands

Specific type of sweat gland

Found near hair folliclesAxillary & genital regions

Develop at puberty

http://www.pg.com/science/skincare/Skin_tws_35.htm

The Skin with Sweat Glands

NailsDorsal surfaces of ends of fingers & toes

Primate featureGrasping

Nail Structure

Nail bodyFree edgeNail root

Matrix

Lunula (moon)

Skin Cancer- MelanomaSquamous Cell

Carcinoma

Basal Cell Carcinoma

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