INTEGUMENTARY SYSTEM

Jhia Anjela D. Rivera1,2

1 Department of Biology, College of Science, Polytechnic University of the Philippines2 Department of Biological Sciences, School of Science and Technology, Centro Escolar University

OBJECTIVES

• To describe the general functions and the organs that comprises the integumentary system

• To describe the appendages of the skin and explain their functional significance

• To correlate the structures with clinical considerations

OUTLINE

• Integumentary System

• Functions of the Skin

• Parts and Layers of the Skin

• Skin Appendages

• Clinical Considerations

• Rule of Nine

INTEGUMENTARY SYSTEM

Components

• Cutaneous membrane

• Epidermis

• Dermis

• Accessory structures

• Subcutaneous layer (hypodermis)

MAJOR FUNCTIONS

• Protection (against abrasion, UV Light, microorganism,

dehydration)

• Sensation (sensory receptors, heat, cold, touch pressure

and pain)

• Vitamin D Production (upon exposure to UV light,

skin produces a molecule → vitamin D for Ca+ homeostasis)

• Temperature Regulation (blood flow and activity of

sweat glands)

• Excretion (waste products)

CLASSIFICATION OF SKIN

SKIN

HIRSUTE GLABROUS

Thin, hairy skin that covers the greater part of the body

Thick, hairless skin that forms the surfaces of the palms, soles and flexor surfaces of the digits

CLASSIFICATION OF SKIN

CLASSIFICATION OF SKIN

CLASSIFICATION OF SKIN

MAJOR LAYERS OF THE SKIN:

- Epidermis- most superficial layer outer portion of the skin

formed of epithelial tissue that rests on the dermis- func: prevents water loss, resists abrasion

- Dermis- dense connective tissue that forms the deep layer of

the skin- func: responsible for structural strength

- Subcutaneous tissue – a layer of connective tissue- func: connects the skin to the underlying muscle and

bone

LAYERS OF THE SKIN

©Seeley’s Anatomy and Physiology, 8th Ed.

EPIDERMIS

Structure: a compound of tissue consisting mainly of a continuously self-renewing, keratinized, stratified squamous epithelium

Several Distinct Cell Layers (Strata)Thick skin – 5 layers (glabrous)Thin skin – 4 layers (hirsute)

In the deepest layer of the epidermis, mitosis occurs. Newlyproduced cells push older cells to the surface where they flakeoff. During this movement, cells change shape and chemicalcomposition through keratinization.

LAYERS OF THE EPIDERMIS

©Seeley’s Anatomy and Physiology, 8th Ed.

LAYERS OF THE EPIDERMIS

©Seeley’s Anatomy and Physiology, 8th Ed.

DERMIS

Structure: composed of dense collagenous connective tissue containing fibroblasts, adipocytes and macrophages.

- An irregular, moderately dense connective tissue

©Seeley’s Anatomy and Physiology, 8th Ed.

LAYERS OF THE SKIN

©Seeley’s Anatomy and Physiology, 8th Ed.

LAYERS OF THE DERMIS: PAPILLARY LAYER

• Underlies epidermis

• Named for dermal papillae

• Loose connective tissue

• Supports, nourishes epidermis

• Provides sensory nerves, lymphatics, and capillaries

LAYERS OF THE DERMIS: RETICULAR LAYER

• Tough, dense, fibrous layer

• Collagen fibers– Limit stretch

• Elastic fibers– Provide flexibility

• Blends into papillary layer (above)

• Blends into subcutaneous layer (below)

SUBCUTANEOUS TISSUE:HYPODERMIS

– Composed of loose connective tissue

– Stabilizes skin position

• Loosely attached to dermis

• Loosely attached to muscle

– Contains many fat cells

• Provides thermal insulation

• Cushions underlying organs

LAYERS OF THE SKIN

©Seeley’s Anatomy and Physiology, 8th Ed.

SKIN APPENDAGES: HAIR

Filamentous cornified structuresEach hair made of a shaft, root and bulb

- Shaft is what you see (dead cells)- Root is below the skin- Bulb located at the base of the root within the follicle- Follicle is the sheath of epidermal cells around the root

SKIN APPENDAGES: HAIR

Filamentous cornified structuresEach hair made of a shaft, root and bulb

- Shaft is what you see (dead cells)- Root is below the skin- Bulb located at the base of the root within the follicle- Follicle is the sheath of epidermal cells around the root

SKIN APPENDAGES: GLANDS

• Sebaceous

– simple, branced acinar glands

– Produce sebum (lubrication of hair and skin to prevent dehydration)

• Sweat

– Eccrine

– Apocrine

SKIN APPENDAGES: SEBACEOUS GLANDS

SKIN APPENDAGES: SWEAT GLANDS

• Eccrine Glands- simple, coiled, tubular glands- Located in almost every part of the body- Produce a salty secretion- Have a ducts that open onto the surface of

the skin through sweat pores

SKIN APPENDAGES: SWEAT GLANDS

• Apocrine Glands- simple, coiled, tubular glands - Produce a thick secretion rich in organic

substances, they open into hair follicles- Particularly large glands of the dermis or

hypodermis

SKIN APPENDAGES: NAIL

• Thin plate, consisting of layers of dead stratum corneum cells that contain a very hard type of keratin

- Nail body (what usually gets painted), - Nail root (covered by skin), - Nail bed (what the nail rests on (stratus

spinosum of the dermis)- Hyponychium = quick (stratum corneum

of the nail)- Eponychium = cuticle (covers the

hidden border…the hangnail area)- Lunula – crested shaped area

CLINICAL CONSIDERATIONS: RULE OF

NINE