theintegumentarysystem-130515100247-phpapp02.pptx

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1. The integument as an organ, nd is an alternative name for skin. a The integumentary system includes the skin and the skin derivatives hair , nails , and glands . The integument as an organ:

2. The Integument Is the largest system of the body 16% of body weight, 1.5 to 2m 2 in area, The integument is made up of two parts: Cutaneous membrane Epidermis– Superficial epithelium Dermis – underlying CT with blood supply Accessory structures Hair Nails Exocrine Glands

3. Protection First line of defense against Bacteria Viruses Protects underlying structures from Ultraviolet (UV) radiation Dehydration Vitamin D production Needed for calcium absorption Sensation Sensory receptors

4. Body temperature regulation If too hot Dermal blood vessels dilate Vessels carry more blood to surface so heat can escape If too cold Dermal blood vessels constrict Prevents heat from escaping Excretion Small amounts of waste products are lost through perspiration

5. Understanding how the skin can function in these many ways starts with understanding the structure of the 3 layers of skin The Epidermis Epithelial tissue Dermis Dense connective tissue proper – irregular Hypodermis Subcutaneous tissue- loose connective tissue proper and adipose tissue

6. Epidermis Dermis Hypodermis or subcutaneous layer

7. The Epidermis Is a vascular stratified squamous epithelium Nutrients and oxygen diffuse from capillaries in the dermis Cells of the Epidermis Keratinocytes Contain large amounts of keratin Are the most abundant cells in the epidermis

8. Epidermis Epidermal ridge Dermal papilla Dermis The structural relationship and interface between the epidermis and underlying dermis. The proportions of the various layers differ with the location sampled.

9. Thin Skin Covers most of the body Has four layers of keratinocytes Thick Skin Covers the palms of the hands and soles of the feet Has five layers of keratinocytes

10. Structures of the Epidermis The five strata of keratinocytes in thick skin From basal lamina to free surface Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum

11. Thick skin LM  210 Surface Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Basement membrane Dermis Papillary layer of dermis E P I D E R M I S

12. Stratum Basale Is attached to basement membrane by hemidesmosomes Forms a strong bond between epidermis and dermis Forms epidermal ridges (e.g., fingerprints) Dermal papillae (tiny mounds) Increase the area of basement membrane Strengthen attachment between epidermis and dermis Has many basal cells or germinative cells

13. Thick skin SEM  25 Pores of sweat gland ducts Epidermal ridge Epidermal ridges

14. Stratum Spinosum — the ―spiny layer‖ Produced by division of stratum basale Eight to ten layers of keratinocytes bound by desmosomes Cells shrink until cytoskeletons stick out (spiny) Continue to divide, increasing thickness of epithelium Contain dendritic (Langerhans) cells , active in immune response

15. Stratum Granulosum — the ―grainy layer‖ Stops dividing, starts producing Keratin A tough, fibrous protein Makes up hair and nails Keratohyalin Dense granules Cross- link keratin fibers

16. Stratum Lucidum — the ―clear layer ‖ Found only in thick skin Covers stratum granulosum Stratum Corneum — the ―horn layer‖ Exposed surface of skin 15 to 30 layers of keratinized cells Water resistant Shed and replaced every 2 weeks

17. The Dermis Located between epidermis and subcutaneous layer Anchors epidermal accessory structures (hair follicles, sweat glands) Two components Outer papillary layer Deep reticular layer Dermis

18. The Papillary Layer Consists of areolar tissue Contains smaller capillaries, lymphatics, and sensory neurons Has dermal papillae projecting between epidermal ridges The Reticular Layer Consists of dense irregular connective tissue Contains larger blood vessels, lymphatic vessels, and nerve fibers Contains collagen and elastic fibers Contains connective tissue proper

19. An inflammation of the papillary layer Caused by infection, radiation, mechanical irritation, or chemicals ( e.g., poison ivy) Characterized by itch or pain Characteristics Strong, due to collagen fibers Elastic, due to elastic fibers Flexible

20. Hair Papillary layer Reticular layer Cutaneous plexus Papillary plexus Epidermal ridges Dermal papillae Capillary loop of papillary plexus

21. The Hypodermis (Subcutaneous Layer) Lies below the integument Stabilizes the skin Allows separate movement Made of elastic areolar and adipose tissues Connected to the reticular layer of integument by connective tissue fibers Deposits of Subcutaneous Fat Distribution patterns determined by hormones Reduced by cosmetic liposuction ( lipoplasty )

22. The Hair Follicle Hair follicles are the organs that form the hairs. Hair follicles are the organs that form the hairs. Located deep in dermis. Produces nonliving hairs. Wrapped in a dense connective tissue sheath. Base is surrounded by sensory nerves ( root hair plexus ). Control bacteria

23. Exposed shaft of hair Sebaceous gland Arrector pili muscle Connective tissue sheath Root hair plexus Accessory Structures of Hair Arrector pili Involuntary smooth muscle Causes hairs to stand up Produces ―goose bumps‖ Sebaceous glands Lubricate the hair

24. Regions of the Hair Hair root Lower part of the hair Attached to the integument Hair shaft Upper part of the hair Not attached to the integument Boundary between hair shaft and hair root Arrector pili muscle Hair shaft Sebaceous gland Hair root Connective tissue sheath Hair bulb Hair matrix Hair papilla

25. Hair Shaft Structure Medulla Core, dead cells contain soft keratin and air to provide flexible Cortex Middle layer, dead cells contain hard keratin to provide stiffness C uticle Outermost, overlapping dead keratinized cells form shiny surface

26. Head: UV protection Cushion from trauma Insulation Nostrils, Ear canals, Eyelashes: Prevent entry of foreign material Body Hair: sensory detection Root hair plexus: Sensory nerves at base of hair follicle that detect slight movement of hair Arrector pili muscle: Attached to every hair follicle Contract to stand hair perpendicular to skin surface

27. Nails Protect fingers and toes Made of dead cells packed with keratin Metabolic disorders can change nail structure Nail Production Occurs in a deep epidermal fold near the bone called the nail root Free edge of Nail Body of Nail Laternal Nail fold Lunula Eponychium (cuticle)

28. Structure of a Nail Nail body The visible portion of the nail Covers the nail bed Lunula The pale crescent at the base of the nail Sides of nails Lie in lateral nail grooves Surrounded by lateral nail folds

29. A cross-sectional view Lateral nail fold Nail body Lateral nail groove Nail bed Phalanx (bone of fingertip)

30. Eponychium Proximal nail fold Nail root Lunula Nail body Epidermis Dermis A longitudinal section Phalanx Hyponychium

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