The musculoskeletal system consists of the skeletal system the bones and joints and the skeletal muscles that move them. The musculoskeletal system provides protection for the brain and internal organs and support for our bones by maintaining upright posture. It also assists in blood cell formation called hematopoiesis, maintains mineral homeostasis and stores fats and minerals. In movement it also acts as a lever which is a simple machine that magnifies speed and provides strength. The levers are mainly the long bones in our body and the axes are the joints where the bones meet.
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The basic element of the skeleton is bone tissue. Bone tissue is a special connective tissue that is supportive but is also flexible enough to allow for growth. When you look inside a bone you will notice that there are two different kinds of bone tissue. If the tissue does not have any open spaces it is known as compact bone. Bone tissue that has many open spaces is known as spongy bone. Spongy bone provides most of the strength and support for a bone. Bones contain a soft tissue known as marrow. Red marrow produces red blood cells and is sometimes found in spongy bone. Yellow marrow stores fat and is found in the central cavity of the long bones. In children red marrow fills the inside of long bones like the femur but is replaced by yellow marrow by adulthood.
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Most of our skeleton starts out as a soft and flexible tissue called cartilage but as we grow the cartilage is replaced by bone. There are some areas that never become bone, like the top part of your ear or the tip of your nose. Cartilage consists of relatively hard, whitish material rich in elastin and collagen fibers. Cartilage is considerably flexible.
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Bone health is important. Strong bones help prevent osteoporosis, a disease in which bones become fragile and break easily. Osteoporosis prevention begins at an early age and continues throughout your lifetime. Bone mass develops rapidly between the ages of 10 and 20 and peaks at age 30. Building and maintaining strong bones depends on calcium, vitamin D, and physical activity.
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Calcium is an important nutrient for your body and for your health. Calcium helps your heart, muscles, and nerves function. It is also important for bone health. Ninety-nine percent of your body’s calcium is stored in your bones. Children and teenagers need adequate calcium in their diets so they can maximize the calcium storage in their bones. In later years, adequate dietary calcium helps minimize calcium loss from the bones. The best sources of calcium are dairy products.
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Your body also uses vitamin D to help transport calcium to your bones. Foods such as milk and eggs contain vitamin D. Your body also makes its own vitamin D when you are exposed to sunlight.
Weight-bearing exercise helps keep bones strong and prevents calcium loss. Calcium loss can take place at any age, even during childhood. For example, astronauts (weightlessness in space) and sedentary people are at risk for losing calcium from their bones. Weight-bearing exercise includes walking, jogging, weight lifting, dancing, and soccer.
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