The Musculoskeletal System

cop.ufl.edu

The Musculoskeletal System

The Musculoskeletal System

Presenters: Judy Riffee

Art Wharton

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Muscle

Made of thick and thin filaments

During contraction, thick filaments grab and pull thin

filaments, creating movement

Individual skeletal muscles are composed of sarcomeres (units

of organized filaments)

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The long bone

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Bone

Composed of two different kinds of bony tissue

Cancellous or “spongy” bone—porous, inner bone that

provides volume

Compact bone—hard, outer covering that provides

strength and shape

The rounded end of a bone is covered with smooth, slippery

articular cartilage

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Bone

Many bones are hollow, and contain marrow:

Red marrow in children

Fatty yellow marrow in adults

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Types of muscle

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Types of Muscle

Skeletal muscles—attached to bones; provide body movement

Voluntary, striated in shape, contain multiple peripheral

nuclei

Cardiac muscle—tissue that composes the heart

Contracts rhythmically, coordinated by transmission of

electrical impulses from nerve to muscle fibers

Smooth or “visceral” muscle—attached to or lines other organs

such as the stomach, intestines, lungs, and blood vessels

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Five Categories of Bone:

The skeleton

Flat bones—generally more flat than round

Examples: cranial bones, rib bones

Irregular bones—have no defined shape

Examples: scapula, vertebrae

Sesamoid bones—have cartilage or fibrous tissue mixed in

Found in the joints; help reduce friction and enhance joint

movement

Example: patella (kneecap)

Short bones—generally cube-shaped

Example: carpals of the hand

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Five Categories of Bone:

Long bones—the most common bone

Divided into two areas:

Epiphysis (the rounded end of the bone)

Diaphysis (the main shaft or central part of the bone)

Example: femur of the leg

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Osteomyelitis—Bacterial Infection

Inside the Bone

Destroys bone tissue

Original site of infection is frequently in another part of body

Infection spreads to the bone via the blood

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Conditions Causing Weak or Brittle

Bones

Osteoporosis—bone brittleness due to lack of calcium

Prevalent in postmenopausal women because of estrogen

deficiency

Paget’s disease—changes the normal process of bone growth

Causes bone to break down more quickly and grow back

softer than normal bone

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Musculoskeletal Diseases/Disorders

Bursitis—inflammation of the small, fluid-filled pouches

between bones

Tendonitis—inflammation of the cords of connective tissue that

attach muscle to bone

Myalgia—muscle pain

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Bone Marrow Disorders

Anemia—failure of the bone marrow to produce red blood cells

Most common cause is lack of iron

Lack of red blood cells leads to a systemic decrease in

oxygen

Causes fatigue

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Bone Marrow Disorders

Leukemia—blood-borne cancer; cancer of the blood

Begins when DNA of white blood cells is damaged or

mutated

Damaged DNA is copied and passed on to subsequent

generations of cells

Abnormal, cancerous cells do not die off like normal cells

Multiply unchecked within the body

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Arthritis—Inflammation of a Joint

Rheumatoid—an autoimmune disorder

Osteoarthritis—caused by physical degeneration of connective

tissue

Gout—caused by crystals of uric acid in blood

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Treating Osteomyelitis

Anti-infective agent is best treatment for osteomyelitis

Pharmacokinetics plays an important role

Physician chooses drug that exhibits the highest anti-infective

activity

Determining factors: least toxicity and lowest cost

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Treating Osteoporosis

Vitamin D and mineral calcium replacement therapy

Hormone therapy (estrogen, calcitonin) and bisphosphonates

Osteoporosis: estrogen replacement therapy (ERT),

hormone replacement therapy (HRT)

Paget’s disease and osteoporosis: bisphosphonates and

calcitonin

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Treating Osteoporosis

SERMs for postmenopausal women

Non-drug treatments for osteoporosis:

Weight-bearing exercise

Smoking cessation

Reduced intake of caffeinated and alcoholic beverages

Calcium intake of about 1,500 mg per day

(postmenopausal); 1,000 mg if on HRT

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Treating Osteoarthritis

Gold compounds used to treat osteoarthritis

Exact mechanism of action is not known

Believed that gold interferes with functions of the white blood

cells responsible for joint damage and inflammation

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Treating Gout

Colchicine used to alter ability of phagocytes to attack uric acid

crystals

Cycle of deposition of uric acid crystals and acid is broken

Anti-inflammatory analgesics can be used to reduce pain and

inflammation

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Treating Inflammation

Salicylates relieve inflammation by inhibiting the synthesis of

prostaglandin

Topical corticosteroids treat most causes, including chemical,

mechanical, microbiological, and immunological

Corticosteroids inhibit the movement of macrophages and

white blood cells, resulting in a decrease in swelling,

redness, and itching

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NSAIDs relieve inflammation and pain, but not infection

Treating Multiple Sclerosis

Autoimmune disease in which body’s immune system begins to

attack normal body tissue

In MS, the immune system attacks cells that make myelin

Treatment of MS includes steroidal anti-inflammatory agents

and corticosteroids

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Treating Cerebral Palsy

Affected person has poor control of the brain, muscles, and

joints

Caused by an injury to the brain before, during, or shortly

after birth

Drug therapy includes drugs to prevent seizures and spasticity

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Musculoskeletal Drugs

ASA (acetylsalicylic acid)

Relieves inflammation by inhibiting the synthesis of

prostaglandin

Salicylates are also used as analgesics and antipyretics

NSAIDs (nonsteroidal anti-inflammatory drugs)

Inhibit or block the enzyme that starts the reaction of

inflammation by making prostaglandin

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Musculoskeletal Drugs

COX-2 inhibitors

Block only the cyclooxygenase II that makes PGE-2, but

not C-1 (PGE-1)

Inflammation is inhibited, but not the viscosity of the

mucosal lining

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Musculoskeletal Drugs

Antigout agents—may be hypouricemic agents or uricosuric

agents

Hypouricemic agents decrease production of uric acid in

the blood

Uricosuric agents increase the excretion of uric acid

through urination

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Musculoskeletal Drugs

Calcitonin—indicated for fragile or soft bones

Inhibits bone resorption

Decreases the number of bone fractures from low bone

density

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Musculoskeletal Drugs

Bisphosphonates—indicated for osteoporosis

Mimic the natural organic bisphosphonate salts found in

the body

Inhibit bone resorption and osteoclast activity

Restore bone mass and density

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Musculoskeletal Drugs

SERMs (selective estrogen receptor modulators)

Indicated for postmenopausal women

Protective effect on bones and heart

Contraindications include a history of breast cancer, liver

problems, or blood clots

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Musculoskeletal Drugs

Skeletal muscle relaxants—used to relax specific muscles in

the body

Relieve pain, stiffness, and discomfort

Block muscle contraction at the neuromuscular junction

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