Skeletal and Muscular Systems. Bone myths

Transcription

1 Skeletal and Muscular Systems Bone myths Myth No. 1: A fracture is a milder form of bone injury than a broken bone. Myth No. 2: Once bones are fully developed, they stop changing. Myth No. 3: Osteoporosis is a painful bone condition. Myth No. 4: Vitamin D deficiency causes rickets, a disease of malnourished children. Myth No. 5: If you have broken a bone, you'll know it right away. Myth No. 6: A broken bone heals stronger than it was before the break. 2

2 Skeletal System The framework for your body 206 bones Os- bone; Osteo- bone Two divisions Axial: Skull, vertebrae, ribs, sternum Appendicular; arms and legs. Contains both bone tissue and cartilage

3 Osteocytes are bone cells 5

4 7 Bone contains: Minerals especially calcium which provides for the hardness of bone Collagen fibers which provides strength of bone If one or the other is missing bones will be soft or brittle

5 Bone has an excellent blood supply Joint art- and arthr- mean joint Ligaments stabilize joints Cartilage caps the bones at the joint for a smooth surface

6 Cartilage chondr- means cartilage Healing capability is poorer than bone Mostly due to decreased blood supply.

7 Skeleton Function Framework; muscles attach Support; allows upright posture Movement; muscle leverage Protection; Brain, lungs, heart, etc. Blood cell production from bone marrow; red and white blood cells Storage of minerals & fat; calcium, phosphate. Fat in yellow marrow.

8 Disorders of Skeleton- Osteoporosis Incidence Common in the U.S. Responsible for many fractures each year Affect 200 million women worldwide - 10% aged 60; 66% women aged 90 Men; 27% for over 50

9 Cause Inadequate calcium Females, older more commonly Sedentary lifestyle Poor diet Pregnancy giving calcium to fetus Menopause leads to calcium withdrawal from bone Prevention/Treatment Weight-bearing exercise Calcium in diet Estrogen replacement therapy after menopause Drugs, such as Fosamax

10 Arthritis Osteoarthritis is the wear and tear arthritis due to joint damage and injuries Arthritis Rheumatoid arthritis is an autoimmune disease in which the immune system attacks the joints in the body leading to their gradual destruction

11 Sprain Joint injury that stretches or tears supportive ligaments A severe sprain can result in a dislocation Fracture Generally bones heal well with proper alignment, stabilization, and without infection

12 Fractures Hairline or greenstick: young, soft bone in which the bone bends and partially breaks Simple Compound = Open; skin is broken Comminuted: bone has broken into a number of pieces.

13 Myo- means muscle Muscular System Muscle tissue is capable of contraction Smooth muscle Found in the wall of tubular structures such as intestine Involuntary Smooth appearance microscopically Peristalsis is a wave like contraction of smooth muscle

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15 Heart muscle Involuntary Cardiac Muscle Striated, or striped when observed microscopically

16 Skeletal Muscle Muscle attached to the skeleton Voluntary Striated microscopically

17 Skeletal Muscle Tendons attach muscle to bone

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19 Myofiber = muscle cell Myofibril = the striated parts of the muscle cell Myofilamen ts = the proteins that make up the myofibrils Microscopic Muscle

20 Myofilaments The two main proteins that comprise the myofilaments are: Myosin very thick protein Actin very thin protein

21 Sarcomere The actin and myosin in the muscle cells are arranged in small groups called SARCOMERES Since contraction occurs at the microscopic level of the sarcomere, the sarcomere is the functional unit of contraction 42

22 Sliding Filament Theory This describes the mechanics of muscle contraction The myosin heads grab on to the actin protein and pull the actin towards the center of the sarcomere, making the sarcomere shorter.

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25 ATP ATP is necessary for muscle contraction Running out of ATP may lead to muscle fatigue

26 Motor Neuron Skeletal muscle will not contract unless a motor neuron (movement nerve cell) stimulates it to contract

27 Motor Unit A motor neuron plus how every many skeletal muscle cells it serves is a motor unit A motor unit that has one neuron to one muscle cell allows for very precise movements A motor unit that has one neuron to 400 muscle cells does not provide precise control