1. C H A P T E R Copyright © 2010 Pearson Education, Inc. 5 The Integumentary System

2. Skin (Integument) Consists of three major regions 1.Epidermis—superficial region 2.Dermis—middle region 3.Hypodermis (superficial fascia)—deepest region Subcutaneous layer deep to skin (not technically part of skin) Mostly adipose tissue 9/21/20092Mickey Dufilho

3. Figure 5.1 Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial fascia) Dermal papillae Pore Subpapillary vascular plexus Appendages of skin Eccrine sweat gland Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Nervous structures Sensory nerve fiber Pacinian corpuscle Hair follicle receptor (root hair plexus) Cutaneous vascular plexus Adipose tissue 9/21/20093Mickey Dufilho

4. Epidermis Keratinized stratified squamous epithelium Cells of epidermis Keratinocytes— Melanocytes--- Epidermal dendritic (Langerhans) cells— Tactile (Merkel) cells — 9/21/20094Mickey Dufilho

5. Figure 5.2a Dermis Stratum corneum Most superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Stratum granulosum Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules. Stratum spinosum Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. Stratum basale Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells. (a) 9/21/20095Mickey Dufilho

6. Layers of the Epidermis: Stratum Basale (Basal Layer) Deepest epidermal layer firmly attached to the dermis Single row of stem cells Also called stratum germinativum: cells undergo rapid division Journey from basal layer to surface Takes 25–45 days 9/21/20096Mickey Dufilho

7. Layers of the Epidermis: Stratum Spinosum (Prickly Layer) Cells contain a weblike system of intermediate prekeratin filaments attached to desmosomes Abundant melanin granules and dendritic cells 9/21/20097Mickey Dufilho

8. Layers of the Epidermis: Stratum Granulosum (Granular Layer) Thin; three to five cell layers in which the cells flatten Keratohyaline and lamellated granules accumulate 9/21/20098Mickey Dufilho

9. Layers of the Epidermis: Stratum Lucidum (Clear Layer) In thick skin Thin, transparent band superficial to the stratum granulosum A few rows of flat, dead keratinocytes 9/21/20099Mickey Dufilho

10. Layers of the Epidermis: Stratum Corneum (Horny Layer) 20–30 rows of dead, flat, keratinized membranous sacs Three-quarters of the epidermal thickness Functions Protects from abrasion and penetration Waterproofs Barrier against biological, chemical, and physical assaults 9/21/200910Mickey Dufilho

11. Figure 5.2b Melanocyte Melanin granule Tactile (Merkel) cell Sensory nerve ending Epidermal dendritic cell Dermis Keratinocytes Stratum corneum Most superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Stratum granulosum Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules. Stratum spinosum Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. Stratum basale Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells. Desmosomes (b) 9/21/200911Mickey Dufilho

12. Dermis Strong, flexible connective tissue Cells include - Two layers: Papillary Reticular 9/21/200912Mickey Dufilho

13. Figure 5.1 Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial fascia) Dermal papillae Pore Subpapillary vascular plexus Appendages of skin Eccrine sweat gland Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Nervous structures Sensory nerve fiber Pacinian corpuscle Hair follicle receptor (root hair plexus) Cutaneous vascular plexus Adipose tissue 9/21/200913Mickey Dufilho

14. Hypodermis Subcutaneous layer deep to the skin Composed of adipose and areolar connective tissue 9/21/200914Mickey Dufilho

15. 15 Synovial Joints Those joints in which the articulating bones are separated by a fluid-containing joint cavity All are freely movable joint _ diarthroses Examples – all limb joints, and most joints of the body

16. 16 Synovial Joints: General Structure Synovial joints all have the following Articular cartilage Joint (synovial) cavity Articular capsule Synovial fluid Reinforcing ligaments

17. 17 Synovial Joints: General Structure Figure 8.3a, b

18. 18 Synovial Joints: Friction-Reducing Structures Bursae – flattened, fibrous sacs lined with synovial membranes and containing synovial fluid Common where ligaments, muscles, skin, tendons, or bones rub together Tendon sheath – elongated bursa that wraps completely around a tendon

19. 19 Synovial Joints: Friction-Reducing Structures Figure 8.4

20. 20 Synovial Joints: Stability Stability is determined by: Articular surfaces – shape determines what movements are possible Ligaments – unite bones and prevent excessive or undesirable motion Muscle tone is accomplished by: Muscle tendons across joints acting as stabilizing factors Tendons that are kept tight at all times by muscle tone

21. 21 Synovial Joints: Movement The two muscle attachments across a joint are: Origin – attachment to the immovable bone Insertion – attachment to the movable bone Described as movement along transverse, frontal, or sagittal planes