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Home , Amphiarthrosis, Axial skeleton, Symphysis, Synarthrosis, Synovial fluid, Synovial membrane

Bio217 Fall 2012 Unit X

Bio217: Pathophysiology Notes Skeletal System Professor Linda Falkow • Forms the body Unit X: Musculoskeletal System & • Supports tissues Integumentary System • Permits movement Chapter 36: Musculoskeletal System – by providing attachment points for muscles • Hemopoiesis (blood formation) Chapter 37: Alterations of Musculoskeletal Function • Mineral storage Chapter 39: Structure, Function & Disorders of the Integumentary System

Elements of Tissue Bone Cells • Rigid . Enable bone to grow, repair, synthesize new bone tissue and • Constituents resorb old tissue – Cells – Fibers . Osteoblast – Ground substance Bone forming cell . Osteoclast – Calcium Reabsorptive bone cell . Osteocyte Transformed osteoblast, maintains matrix

Bone Matrix Bone Tissue extracellular components • Compact (cortical) bone • Collagen fibers – tensile strength – 85% of the – Haversian system (osteon) • Proteoglycans - strengthen bone, transport Ca++ • Haversian (central) canal, lamellae, lacunae, osteocyte, and canaliculi • Glycoproteins – regulate collagen interactions  fibril formation • Spongy (cancellous) bone • Bone mineralization – crystals of HAP – Lack haversian systems

(hydroxyapatite) (Ca & PO4) – Trabeculae

• Periosteum

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Bone Tissue Bone

Structure of • 206

compact bone • Axial skeleton – 80 bones & • , ,

cancellous bone • – 126 bones • Upper and lower extremities, pectoral and pelvic girdle

Bones Long Bone

• Long bones – Upper and lower extremities • Flat bones Longitudinal – and scapulae section of • Short bones (cuboidal bones) long bone – Wrist and ankles • Irregular bones – Vertebrae, , facial bones

Bone Remodeling and Repair

Bone remodeling • classifications based on movement – Maintains internal structure – – Repair microscopic injuries • Immovable Bone Repair – – Fractures and gross injuries • Slightly movable – Inflammation/hematoma formation – Procallus formation – Diarthrosis – Callus formation • Freely movable – Callus replacement – Remodeling

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Joints Joints • Joint classifications based on structure – Fibrous A. E. Suture

• Joins bone to bone • Suture, syndesmosis, gomphosis B. F. Ball & socket – Cartilaginous

• Symphysis and synchondrosis – Synovial C. Symphysis G. Hinge

• Uniaxial, biaxial, or multiaxial

• , , joint cavity, D. Syndesmosis H. Gliding , articular

Joints Movements Joint (synovial)

Body Movements by Synovial Joints Joints Skeletal Muscles

• Millions of individual muscle fibers (= muscle cells) contract and relax to facilitate movement

• More than 600 in body

• 2 to 60 cm long

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Skeletal Muscles Skeletal Muscles Whole muscle

Fascia (3 part CT framework) – Epimysium  Entire belly of muscle – Perimysium  Fascicles (bundles of muscle fibers) – Endomysium  Individual muscle fiber

Muscle Muscle Fibers • Sarcotubular system • – Transverse tubules – Sarcoplasmic reticulum (SR) – Voluntary – Striated • Sarcomere (myofibrils) – Motor units – Muscle proteins • Actin • Myosin • Troponin-tropomyosin complex

• Nonprotein components: – Creatine and creatinine – Phosphate, chloride, calcium, magnesium, sodium, potassium

Myofibrils Myofibrils

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Muscle Contraction Muscle Metabolism

• Excitation • Requires constant supply of ATP and – Muscle fiber action potential phosphocreatine (CP creatine phosphate) • Coupling • Contraction • Strenuous activity requires oxygen – Cross-bridge theory • Relaxation • Type I fibers can resist fatigue longer than type II fibers

• 3. Joints are classified functionally & structurally. Which is a correct Concept Check functional/structural relationship? • A. Amphiarthrosis/fibrous C. Synarthrosis/ synchrondrosis • 1. The skeletal system: • B. Diarthrosis/ synovial D. Diarthrosis/ fibrous – A. Supports tissues E. Synarthrosis/ cartilaginous

– B. Binds organs together • 4. Which is not included in a motor unit? – C. Protects CNS structures – A. Muscle fibers – D. Involved in blood cell production – B. Motor nerve axons – C. Anterior horn cell – E. Lines body cavities – D. Upper motor neuron

• 2. A function of the that is not a • 5. Which are correctly matched? function of articular cartilage: – A. Sarcomere – unit of contraction – B. Sarcolemma – membrane covering the muscle cell – A. Enable articulation of bones – C. Sarcoplasmic reticulum – Ca storage and transport – B. Enable bones to increase in length D. All of the above are correct – C. Repair damaged bone – D. Provide sensory nerves to bone

Musculoskeletal Injuries • Fractures • Alterations of Musculoskeletal Function = break in a bone

– Classifications

• Complete or incomplete (broken completely through or not) • Chapter 37 –Closed or open (compound) (skin intact or skin is broken) • Comminuted - fragmented • Linear – break is parallel to long axis of bone • Oblique – break at an oblique angle • Spiral – encircles bone • Transverse – at right angles to long axis

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Fracture Classifications Fractures

• Greenstick – incomplete break • Torus - buckling of bone • Bowing – bending of bone • Pathologic – due to disease (osteoporosis) • Stress – microfracture often due to repeated stress, common in athletes

Bone Fractures Callus Formation

Pathophysiology A. Hematoma

Bleeding at ends of bone  B. Fibrous – Hematoma formation network

Bone tissue destruction  inflammatory response C. Ca deposition – Procallus formation – Callus formation – Callus reabsorption D. Callus fomation – Remodeling E. Remodeling

Callus Formation Bone Fractures

Dislocation Excessive callus – Temporary displacement of two bones formation – Loss of contact between articular cartilage

Subluxation – Contact between articular surfaces is only partially lost

Both caused by trauma

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Support Structure Injuries and

• Strain • Tendinitis – Tear or injury to a tendon – Inflammation of a tendon • Sprain • Bursitis – Tear or injury to a – Inflammation of a bursa • Avulsion – Complete separation of a tendon or • Epicondylitis ligament from its bony attachment site – Inflammation of a tendon where it attaches to bone • Tennis (lateral epicondylitis) • Golfer’s elbow (medial epicondylitis)

Tendinopathy and Bursitis Rhabdomyolysis

• Rhabdomyolysis (myoglobinuria) is a life- threatening complication of severe muscle trauma with muscle cell loss – Excess myoglobin in urine due to muscle damage

• Pathophysiology – Wt. of limp extremity  ischemia  edema   necrosis (cell loss)

Osteoporosis Osteoporosis • Metabolic bone disorder  decreased bone mass • Potential causes (bone resorption >> bone deposition) – Decreased levels of estrogens and • Porous bone testosterone • Poorly mineralized bone – Decreased activity level • Bone density – Inadequate levels of vitamins D, C, or Mg++ – Normal bone : 833 mg/cm2 (diet or absorption problems) – Osteopenic bone : 833 to 648 mg/cm2 – Osteoporosis: <648 mg/cm2

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Osteoporosis Osteoporosis

Vertebral body – normal on left; compression fractures of osteoporosis on right

Osteoporosis Osteoporosis Iatrogenic osteoporosis – Patients on heparin ( bone resorption)

Regional osteoporosis – Disuse of body region, or weightlessness  uniform dist. of bone loss

Postmenopausal osteoporosis – Decreased level of estrogens, or hyperparathryoidism

Glucocorticoid-induced osteoporosis (cortisone incr. bone resorption, decr. formation)

Age-related bone loss –begins in 4th decade

Osteoporosis Osteoporosis

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Osteomalacia Paget Disease • Abnormal remodeling - irregular resorption and Metabolic disorder  inadequate deposition of bone mineralization (aka adult rickets) – (aka osteitis deformans)

Deficiency of vitamin D lowers the absorption of Ca from the intestines • Disorganized, thickened, but soft bones

Bone formation progresses to osteoid • Most often affects the axial skeleton formation but calcification does not – Skull thickens  compresses brain tissue occur  soft bones –  cranial nerves impacted – Pain, bone fractures, vertebral collapse, bone –  hearinig loss malformation • Idiopathic, viral ?

Osteomyelitis Pathophysiology: Infectious bone disorder – Bone  inflammatory response Caused by a staphylococcal infection  (vascular engorgement, edema incr. WBCs, abcess formation – Exudate can seal canaliculi , extend into Most common cause is open wound metaphysis and marrow (exogenous); also can be from blood- borne (endogenous) infection Manifestations – Acute and chronic inflammation, fever, pain, necrotic bone

Treatment – Antibiotics, débridement, surgery, hyperbaric oxygen therapy

Osteomyelitis Osteomyelitis

Osteomyelitis showing sequestration and involucrum

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Osteoarthritis (OA)

• aka Inflammatory Joint Disease Most common form of  erosion of articular cartilage • Characterized by inflammatory damage or bone spurs (osteophytes) destruction in the synovial membrane or

articular cartilage and by systemic signs Age related of inflammation – Fever, leukocytosis, malaise, anorexia, and Affects mostly and , can affect any joint hyperfibrinogenemia Primary disease is idiopathic (metabolic factors, genetics, chemical & mechanical factors)

Osteoarthritis Osteoarthritis

OA characterized by local areas of damage and Degeneration loss of articular cartilage, new bone formation of joint margins, subchondral of cartilage of bone changes, mild and joint thickening of the joint capsule

Manifestations – Pain, stiffness, enlargement of the joint, tenderness, limited motion, and deformity

Osteoarthritis (RA)

• Chronic, progressive, systemic, Nodes form in inflammatory disorder of joints proximal and distal • Systemic autoimmune damage to CT, joints of fingers primarily in the joints (synovial membrane) • Affects symmetrical joints

(proximal ) • Similar symptoms to osteoarthritis

(distal)

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Rheumatoid Arthritis Rheumatoid Arthritis

• Presence of rheumatoid factors (RA or RF test) • Pathogenesis – Antibodies (IgG and IgM) against antibodies – CD4 T helper cells and other cells in the synovial fluid become activated and release cytokines • Synovitis  edema and inflammed synovial membrane – Recruitment and retention of inflammatory cells in the joint sublining region

– Cycle of altered cytokine and signal transduction pathways

Rheumatoid Arthritis Rheumatoid Arthritis

• Evaluation – Four or more of the following: • Morning joint stiffness lasting at least 1 hour • Arthritis of three or more joint areas • Arthritis of the joints • Symmetric arthritis • Rheumatoid nodules • Abnormal amounts of serum rheumatoid factor • Radiographic changes

Rheumatoid Arthritis

• Inflammatory joint disease of spine or sacroiliac joints causing stiffening and fusion of joints

• Systemic, immune inflammatory disease

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Ankylosing Spondylitis Ankylosing Spondylitis

Primary proposed site is the • Begins with inflammation of of – Site where , tendons, and joint vertebrae and capsule are inserted into bone • Inflammatory cells infiltrate and erode fibrocartilage Cause unknown, but strong association with HLA-B27 antigen • As repair begins, scar tissue ossifies & calcifies; joint eventually fuses

Ankylosing Spondylitis Ankylosing Spondylitis

• Early symptoms – Low back pain, stiffness, pain, and restricted motion

• Patient demonstrates loss of normal lumbar curvature

Gout

• Metabolic disorder • Mechanisms for crystal deposition  disrupts the body’s control of uric acid – Lower body temperatures, decreased production or excretion albumin or levels, changes in ion concentration and pH, and • High levels of uric acid in blood and other trauma body fluids • Uric acid crystals are deposited in CT • Clinical stages – • When these crystals occur in the synovial Asymptomatic hyperuricemia fluid, inflammation is known as “gouty – Acute gouty arthritis arthritis” – Tophaceous gout

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Gout Fibromyalgia

• Chronic widespread joint and muscle pain

• Vague symptoms – Increased sensitivity to touch, absence of inflammation, fatigue, and sleep disturbances

Fibromyalgia Fibromyalgia

• Possible factors – Flulike viral illness, chronic fatigue syndrome, HIV infection, , medications, physical or emotional trauma

• Scientific studies are unclear

Bone Tumors Osteosarcoma

• Osteosarcoma – 38% of bone tumors

– Predominant in adolescents and young adults; occurs in seniors if history of radiation therapy

– Contain masses of osteoid • “Streamers”: noncalcified bone matrix and callus

– Located in the metaphyses of long bones • 50% occur around the knees

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Concept Check Matching: • 1. In a complete fracture: • 3. subluxation a. Compound fracture A. Fracture crosses the entire width of bone • 4. b. Common in elderly & B. more than 2 bone fragments present children C. separation of ligament exits • 5. open fracture c. Lateral epicondylitis D. the surface opposite break is intact. • 6. greenstick fracture d. Partial loss of contact 2. Which is a definite sign of fracture? between bone surfaces A. abrasion B. Shock Matching: C. Muscle spasm 7. OA e. Buildup of uric acid D. unnatural alignment 8. RA f. Staph infection in bone 9. Osteomyelitis g. Affects wt.-bearing joints, bone spurs form 10. Gout h. Inflam., autoimmune, affects

Matching: • 11. ankylosing spondylitis • 12. fibromyalgia • 13. osteosarcoma Structure, Function, and • 14. rhabdomyolysis Disorders of the Integument a. Muscle damage  myoglobinuria Chapter 39 b. Malignant bone tumor c. Fatigue and muscle pain, sensitive to touch d. Ossification & fusion of vertebral column

Regions of the Skin Regions

• Epidermis • Dermal appendages • Dermis – Nails – Hair • Hypodermis – Sebaceous glands -lies deep to – Eccrine and apocrine sweat glands skin • Blood supply – Papillary capillaries

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Nails Aging and Skin Integrity • Integumentary system reflects numerous changes from genetic and environmental factors – Skin becomes thinner, drier, wrinkled, and demonstrates changes in pigmentation – Shortening and decrease in number of capillary loops – Fewer melanocytes and Langerhans cells – Atrophy of the sebaceous, eccrine, and apocrine glands – Changes in hair color – Fewer hair follicles and growth of thinner hair

Clinical Manifestations of Elevated Lesions Skin Dysfunction • Flat Lesions • • 1. Macule – flat, circumscribed,discolored lesion, <1 cm; 6. Papule –elevated, firm area, < 1 cm;  freckle, nevus, petechia, measles wart, elevated moles, lichen planus • • 2. Patch – flat, irregular lesion, >1 cm; 7. Plaque – elevated, firm, rough lesion with flat top > 1 cm; psoriasis, eczema vitiligo, port wine stains • 8. Nodule – elevated, firm lesion, deeper in dermis than papule, 1-2 cm; o 3. Petechiae – circumscribed area of blood < 0.5 cm; lipoma, Ca deposits thrombocytopenia • 9. Wheal – transient, well defined and often changing borders; • 4. Purpura – circumscribed area of blood > 0.5 cm; hives, insect bites, allergic reaction bruises • 10. Vesicle and bulla – fluid-filled, thin walled lesion, bulla >1 cm; • 5. Telangiectasia – fine, irregular red lines due to dilated blister, herpes zoster, 2o burns superficial blood vessels; RA, rosacea • 11. Pustule – lesion containing WBC exudates;

acne, impetigo

More Elevated Lesions Depressed Lesions • 12. Comedo – plugged hair follicle; o 19. Atrophy – thinning of epidermis or dermis due to  blackhead, whitehead decreased CT; • 13. Scale – accumulation of stratum corneum; thin skin of elderly  psoriasis • 20. Ulcer – loss of epidermis and dermis; • 14. Crust – accumulation of dried blood or serum; pressure sores, basal cell carcinoma  eczema, impetigo o 15. Lichenification – thick, tough skin due to rubbing or itching; o 21. Excoriation – loss of epidermis w/ exposed dermis;  chronic dermatitis  scratches o 16. Cyst – encapsulated mass of dermis, solid or fluid filled; • 22. Fissure – crack or break exposing dermis;  sebaceous cyst Athlete’s , crack in corner of mouth • 17. Tumor – solid lesion > 2 cm; • 22. Erosion – moist, red break in epidermis after  fibroma, lipoma, melanoma rupture of vesicle or bulla, larger than fissure; • 18. Scar – thin or thick fibrous tissue; Chickenpox, diaper dermatitis  healed laceration, burn or incision

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Pressure Ulcers Pressure Ulcers

• Result from any unrelieved pressure on skin, causing underlying tissue damage – Pressure – Shearing forces – Friction – Moisture

Progression of decubitis ulcer: Compressed tissue over bony prominence  ischemia  necrosis

Keloids Pressure Ulcers

• Stages • Elevated, rounded, and firm – Nonblanchable erythema of intact skin • Clawlike margins extend beyond original – Partial-thickness skin loss involving injury site epidermis or dermis • Excessive collagen formation during dermal CT – Full-thickness skin loss involving damage or repair loss of subcutaneous tissue • Common in darkly pigmented skin types and – Full-thickness skin loss with damage to burn scars muscle, bone, or supporting structures • Type III collagen is increased

Pruritus Disorders of the Skin

• Itching • Inflammatory disorders • Most common symptom of primary skin disorders – Most common inflammatory disorder of skin is • Itch is carried by specific unmyelinated C-nerve dermatitis or eczema fibers and is triggered by a number of itch mediators – Various types of dermatitis exist • The CNS can modulate the itch response – Disorders are generally characterized by pruritus, lesions with indistinct borders, and epidermal changes o Pain stimuli at lower intensities can induce itching

o Chronic itching can result in and scarring due to persistent scratching

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Inflammatory Disorders Inflammatory Disorders • Allergic contact dermatitis • Allergic contact dermatitis – Manifestations – Caused by a hypersensitivity type IV reaction • Erythema, swelling, pruritus, vesicular lesions

– Allergen comes in contact with skin, binds to a A. Poison Ivy on knee carrier protein to form sensitizing antigen; Langerhans cells process antigen and carry it to T cells, which become sensitized to the antigen

B. Poison Ivy dermatitis

Inflammatory Disorders Inflammatory Disorders • Irritant contact dermatitis – Nonimmunologic inflammation of the skin • Seborrheic dermatitis – Chemical irritation from acids or prolonged exposure to – Inflammation of the skin involving scalp, eyebrows, irritating substances (soaps, detergents, industrial eyelids, nasolabial folds, and canals agents) – Scaly, white, or yellowish plaques – Symptoms similar to allergic contact dermatitis – Treatment—remove stimulus

• Stasis dermatitis – Occurs in legs as a result of venous stasis, edema, and vascular trauma – Sequence of events: erythema, pruritus, scaling, petechiae, ulcerations Stasis and Seborrheic Dermatitis

Papulosquamous Disorders Papulosquamous Disorders

• Psoriasis – Chronic, relapsing, proliferative skin disorder Psoriasis – T cell immune–mediated skin disease Guttate Psoriasis after Strep infection – Scaly, thick, silvery, elevated lesions, usually on scalp, , or knees caused by a high mitotic rate in basale layer

– Shows evidence of dermal and epidermal thickening – Epidermal turnover goes from 26-30 days to 3-4 days – Cells do not have time to mature or adequately keratinize

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Papulosquamous Disorders Papulosquamous Disorders

• Pityriasis rosea – Benign, self-limiting inflammatory disorder – Usually occurs during the winter months – Herald patch • Circular, demarcated, salmon-pink, 3- to 4-cm lesion

Papulosquamous Disorders Papulosquamous Disorders

• Lichen planus • Acne vulgaris – Benign, inflammatory disorder of the skin and – Inflammatory disease of the pilosebaceous follicles mucous membranes – Unknown origin, but T cells, molecules, o Acne rosacea inflammatory cytokines, and antigen presenting Inflammation of the skin that develops in adulthood cells are involved Lesions – Nonscaling, violet-colored, Erythematotelangiectatic, papulopustular, phymatous, 2- to 4-mm lesions and ocular Associated with chronic, inappropriate VD resulting in – Wrists, ankles, lower legs, genitalia flushing and sensitivity to sun

Papulosquamous Disorders Vesiculobullous Disorders • erythematosus – Inflammatory, autoimmune disease with • Pemphigus cutaneous manifestations – Rare, chronic, blister-forming disease of skin and oral mucous membranes – Discoid lupus erythematosus – Blisters form in deep or superficial epidermis • Restricted to the skin – Autoimmune disease caused by circulating IgG autoantibodies • Photosensitivity • Butterfly pattern over the nose and cheeks

– Systemic lupus erythematosus

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Vesiculobullous Disorders Vesiculobullous Disorders

• Pemphigus • Bullous pemphigoid – Tissue biopsies demonstrate autoantibody presence – More benign disease than pemphigus vulgaris – Types – Bound IgG and blistering of the subepidermal skin layer – Subepidermal blistering and eosinophils distinguish • Pemphigus vulgaris (severe) pemphigoid from pemphigus • Pemphigus foliaceus • Pemphigus erythematosus

Vesiculobullous Disorders Vesiculobullous Disorders

• Erythema multiforme • Erythema multiforme – Acute, recurring disorder of the skin and mucous – “Bull’s-eye” or target lesion membranes • Erythematous regions surrounded by rings of – Associated with allergic or toxic reactions to drugs or alternating edema and inflammation microorganisms

– Caused by immune complexes formed and deposited – Bullous lesions form erosions and crusts around dermal blood vessels, basement membranes, and keratinocytes when they rupture – Affects the mouth, air passages, esophagus, urethra, and conjunctiva

Infections Infections

• Bacterial infections • Viral infections – Folliculitis – Herpes zoster and varicella – Furuncles – Carbuncles – Cellulitis – Erysipelas – Impetigo

HERPES SIMPLEX VIRUS HERPES ZOSTER

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Warts Fungal Infections

• Benign lesions caused by the • Fungi causing superficial skin lesions are called dermatophytes human papillomavirus (HPV) • Fungal disorders are called mycoses; mycoses • Diagnosed by visualization caused by dermatophytes are termed tinea • Condylomata acuminata – Tinea capitis (scalp) – Tinea pedis (athlete’s foot) – Venereal warts – Tinea corporis (ringworm) – Tinea cruris (groin, jock itch) – Tinea unguium (nails) or onychomycosis

Fungal Infections Vascular Disorders • Candidiasis – Caused by Candida albicans • Cutaneous vasculitis – Results from immune complexes in small blood vessels – Normally found on the skin, in the GI tract, and in vagina • Develops from drugs, bacterial infections, viral infections, or allergens – C. albicans can change from a commensal organism to a – Lesions pathogen • Palpable purpura progressing to hemorrhagic bullae • Local environment of moisture and warmth, systemic with necrosis and ulceration administration of antibiotics, pregnancy, diabetes mellitus, Cushing’s disease, debilitated states, age < 6 months, immunosuppression, and neoplastic diseases

Vascular Disorders Vascular Disorders

• Urticaria • – – Sclerosis of the skin that can progress to internal Caused by type I hypersensitivity reactions to organs allergens – The disease is associated with several antibodies – Histamine release causes endothelial cells of – Lesions exhibit massive deposits of collagen skin to contract with inflammation, vascular changes, and capillary dilation • Causes leakage of fluid from the vessels – Skin is hard, hypopigmented, taut, and tightly – Treatment connected to underlying tissue • Antihistamines and steroids

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Vascular Disorders Insect Bites • Scleroderma – Facial skin becomes very tight • Bees – Fingers become tapered and flexed; nails and • Mosquitoes fingertips can be lost from atrophy • Flies – Mouth may not open completely – 50% of patients die within 5 years

Benign Tumors Cancer

• Seborrheic keratosis • Basal cell carcinoma • Keratoacanthoma • Squamous cell carcinoma • Actinic keratosis • Malignant melanoma • Nevi (moles) • Kaposi sarcoma

Cancer Cancer

Basal Cell Carcinoma Squamous Cell Carcinoma on ear Lentigo Malignant Melanoma Karposi Sarcoma

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Burns Rule of Nines

• Partial-thickness burns – First degree • Superficial and deep partial – Second degree • Full-thickness burns – Third degree • “Rule of nines”

Burns Frostbite

• Skin injury caused by exposure to extreme cold • Usually affects fingers, toes, , nose, and cheeks • The “burning reaction” is caused by alternating cycles of vasoconstriction and vasodilation

• Inflammation and reperfusion are both part of the pathophysiology

Hypertrophic Scarring Autograph of Cultured Epithelial cells due to deep partial-thickness injury

Disorders of the Hair Disorders of the Hair

• Male-pattern alopecia • Alopecia areata – Genetically predisposed response to androgens – Autoimmune T cell–mediated inflammatory disease – Androgen-sensitive and androgen-insensitive against hair follicles that results in baldness follicles • Hirsutism – Androgen-sensitive areas • Female-pattern alopecia • Abnormal growth and distribution of hair on the – Associated with elevated levels of the serum face, body, and pubic area in a male pattern that adrenal androgen dehydroepiandrosterone sulfate occurs in women – No loss of hair along the frontal hairline

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• 7. Which are most likely to undergo malignant Concept Check: transformation? • 1. Which layer of the epidermis contains dead keratinocytes? – A. Corneum D. Spinosum – A. Seborrheic keratosis – B. Luicidum E. Germinativum (Basale) – B. Nevi – C. Granulosum – C. Actinic keratosis • 2. The dermis is composed of all of the following except: – D. B and C are correct – A. Melanocytes D. Apocrine sweat glands – B. Collagen E. Sebaceous glands – C. Elastin • 8. A burn that destroys the epidermis and Match the lesion with the example: dermis is: 3. Macule A. hives – A. 1st degree 4. Nodule B. psoriasis – B. 2nd degree 5. Scale C. lipoma rd 6. Wheal D. freckle – C. 3 degree

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