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INTEGUMENTARY SYSTEM

Chapter 5

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Components of Integumentary

System Cutaneous Membrane

superficial

epithelium-epidermisunderlying

connective tissue-

dermis

underneath the dermis-

subcutaneous layer

Accessory structures

located in the dermis

-hair nails

exocrine glands

(sebaceous and sweat

glands)

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Functions of the Skin

Protection-of underlying tissues and organs

Excretion-of salts, water and organicwastes

Maintenance of normal body temperature

Synthesis of Vitamin D3

Storage of nutrients

Sensory function-detection of touch,

pressure, pain and temperature.

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EPIDERMIS Provides mechanical protection.

Helps keep microorganisms outside the

body.

Layer consists of stratified squamous

epithelium.

The most abundant epithelial cells, the

keratinocytes form different layers.

Thick skin (5) and thin skin (4)-refer only

to the epidermis.

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EPIDERMAL LAYERS Stratum Germinativum (basale)

Stratum Spinosum

Stratum Granulosum

Stratum Lucidum

Stratum Corneum

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Stratum Germinativum This layer is firmly attached to the basement

membrane.

Epidermal Ridges

Most of the cells are keratinocytes.

Stem cells divide and replace with the cells

on top (keratinocytes)

these cells are also nourished by the

adjoining tissues in the dermal layer.

The accessories arise from this la er.

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Stratum Spinosum This consists of 8-10 layers of cells

Also contain Langerhans cells, part of the

immune system (defense against

microorganisms and cancers).

Cannot be distinguished in standard

histological procedures.

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Stratum Granulosum This is also called the grainy layer.

Contains 3-5 layers of keratinocytes.

Manufacture keratohyalin and keratin.

Keratin is the basic component of hair and

nails.

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Stratum Lucidum In the thick skin of the palms and soles.

Cells in this layer are flattened, densely

packed and filled with keratin.

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Stratum Corneum These contain 15-30 layers of keratinized

cells.

This layer is water-resistans but not

waterproof.

Takes 15-30 days to move from base to top.

Coated with lipid secretions from sebaceous

and sweat glands.

Insensible vs.sensible persipiration.

Xerosis

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Skin Pigmentation Interaction between pigment composition

and concentration and the dermal blood

supply.

Pigments are melanin and carotene.

Melanocytes secrete melanin. Amount of

pigment varies.

Melanin is produced from the amino acid

tyrosine.

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Skin Pigmentation Carotene, a yellow orange pigment is a

precursor of vitamin A. This is found in the

stratum corneum and fatty areas of the

dermis and subcutaneous layer.

Melanin protects against UV damage.

Albinism is an inherited disorder, where theindividual is unable to produce melanin.

Vitiligo, irregular white spots.

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Dermal Circulation Red blood cells contain hemoglobin.

When bound to oxygen-bright red color

when oxygen is removed-darker red tone.

Seen from surface a bluish coloration called

cyanosis.

Also response to respiratory or circulatory

disorders.

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DERMIS Pappilary layer -consists of loose

connective tissue, capillaries and neurons.

reticular layer - dense irregular connective

tissue.

Accessory organs of epidermal origin, such

as hair follicles and sweat glands extendinto the dermis.

Sensory receptors_ Meissners and Pacinian

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Accessory Structures

Hair Anatomy of hair

Hair Growth

Hair color

Hair functions-protection from UV light,

cushion a blow and insulate the head,

prevent entry of foreign materilas.

Arrector pilli muscle.

Types of hair-velllus and terminal

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Accessory Structures

Glands Sebaceous Glands- holocrine, secrete

sebum. Provides lubrication and inhibits

growth of bacteria.

Sudoriferous Glands (sweat glands)-

apocrine or merocrine. Coolong the surface

of skin, excretion and protection. Mammary Glands-

Ceruminous Glands

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Accessory Structures

Nails Anatomy of the nail-consists of dead,

tightly compressed cells packed with

keratin.

Function of the nail

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Injury and Repair Scab

Granulation Tissue

Scar Tissue

Keloid

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Aging and the Integumentary

System Epidermis thins

Langerhans cells decrease

Vitamin D production decreases

Melanocyte activity declines

Glandular activity declines Blood supply to dermis is reduced

Dermis thins