Kinesiology PDF

KINESIOLOGY Ossification bone growth, babies are cartilage, as ossification occurs, they turn into bones 1. Primary ossification center begins in the middle of the bone 2. Secondary ossification centers are at the ends of the bone 3. Medullary cavity forms w bone marrow 4. Ossification...

KINESIOLOGY Ossification bone growth, babies are cartilage, as ossification occurs, they turn into bones 1. Primary ossification center begins in the middle of the bone 2. Secondary ossification centers are at the ends of the bone 3. Medullary cavity forms w bone marrow 4. Ossification centers meet at the epiphyseal plate, articular cartilage forms, turns into epiphyseal line and growth ends Bone remodeling 10 percent of the skeletal mass of an adult is being remodeled each year. osteoclasts bone cells that resorb bone and dissolve its minerals; osteoblasts bone cells that make the new bone matrix. Wolf's law Bone remodeling allows bones to adapt to stresses by becoming thicker and stronger when subjected to stress. Fractures Transverse straight across the long axis Impacted one bone driven into another Oblique at an angle that's not 90 degrees Greenstick one side is broken, fresh kids Spiral segments pulled apart cus of twisting bones motion Open (compound) bone goes out of the skin Comminuted many small pieces Closed (simple) stays intact Stages of Repair 1. Hematome forms (blood clot) 2. Internal and external calli form cartilaginous matrix causing bulge 3. Calli turns cartilage into trabecular bone (spongy bone formation) 4. Remodeling occurs Building Strong Bones Bones gain in density until 30, need Calcium, vitamin D (dark greens), Vitamin A, K, physical activity, no use of substances. Osteoporosis Age-related disorder, bones lose mass, weaken, and break more easily, fracture can occur with minor stress or without any stress. due to an imbalance between bone formation by osteoblasts and bone resorption by osteoclasts. Why imbalance? 1. An individual might not have developed normal peak bone mass during the young adult years (hormone intake) 2. There might be greater than normal bone resorption: 3. There might not be enough formation of new bone by osteoblasts during remodeling Risk Factors 6. smoking 1. older age 7. alcohol consumption 2. XX chromosome 8. lack of exercise 3. European or Asian ancestry 9. vitamin D deficiency 4. family history of osteoporosis 10. poor nutrition 5. short stature and small bones 11. consumption of soft drinks Osteoarthritis Joint pain and reduces joint mobility and function  MUSCLES SMOOTH SKELETAL CARDIAC Non-striated Striated Striated Spindle shaped Tubular shaped Branched Uninucleated (1 nucleus) multinucleated Uninucleated involuntary Voluntarily involuntary INTERNAL ORGANS ATTACHED to SKELETON HEART MUSCLES Muscle fiber Sarcomere is the smallest functional unit of skeletal muscle fiber. Each muscle fiber is composed of many myofibrils. Myofibrils are composed of actin (thin filaments), myosin (thick filaments), and support proteins.  Myofibrils composed of myofilaments: thick filaments and thin filaments. Thick filaments occur only in the A band of a myofibril, (Myosin protein) Thin filaments attach to a protein in the Z disc called alpha-actinin and occur across (actin protein) (tropomyosin, troponin) the entire length of the I band and partway into the A band. Motor Unit Single motor neuron with multiple axon terminals that can innervate many muscle fibers Neuron axon terminal and a muscle fiber connect at a neuromuscular junction site. Initial Muscle Contraction 1. Action potential is initiated in the motor neuron. 2. It travels to neuromuscular junction (where the nerve meets the muscle) 3. At axon terminal, messenger ACh is released 4. ACh diffuses and binds to receptors on muscle cells surface 5. The binding opens Na ion channels, so action potential comes into the sarcolemma 6. Action potential travels along T-tubules deeper into the muscle fiber 7. That triggers the opening of calcium channels in the sarcoplasmic reticulum so Ca+2 diffuses out of SR into sarcoplasm. 8. Those released Ca+2 bind to the proteins troponin and tropomyosin, getting them to move aside so that the actin binding sites can attach to the myosin head. 9. Myosin pulls the actin filaments, shortening the muscle fiber Thick and thin filament interaction leads to muscle contraction Sarcoplasmic reticulum: helps w contracting and relaxing muscles by storing releasing calcium ions Sliding filament theory Cycle of thick myosin filaments attach to and pull on the thin actin filaments. Sliding over another. The actin filaments are connected to Z discs (marking the end of sarcomeres), so anytime they slide, they bring Z discs closer together, shortening the muscle fibers, which means contracting. Myosin crossbridges 1. Myosin head binds to actin filament (holding ATP and Pi) 2. Myosin head pulls the actin filament towards sarcomeres center (shortening it) which releases ADP and Pi, (myosin still attached to actin) 3. ATP binds to myosin to detach it from actin 4. ATP splits into ADP and Pi and resets the myosin head (cocked position) cycle repeats.