1 Each muscle fibre ( muscle cell ) is covered by a plasma membrane sheath which is called the sarcolemma. 2  Tunnel-like extensions from the sarcolemma pass through the muscle fibre from one side of it to the other in transverse sections through the diameter of the fibre.keletal muscles consist of 100,000s of muscle cells (also known as muscle fibers) that perform the functions of the specific muscle of which they are a part.
Green vegetables are also a major source of iron and calciumfor any diet. Swiss chard and spinach are not considered good sources of calcium, due to their high content of oxalic acid. Green leafy vegetables are rich in beta-carotene, which can also be converted into vitamin A, and also improve immune function. Millions of children around the world have an increased risk of blindness, and other illnesses because of inadequate dietary vitamin A from green leafy vegetables.
Bones Need Vitamins, Too. Dark, leafy greens, including beet leaves, are the best sources of vitamin K. This vitamin is needed to make proteins that stop bleeding by clotting blood.You also need vitamin K to keep your bones strong and prevent osteoporosis.ven though some nutrients, especially vitamin C, are lost when greens are cooked, when you compare a 1-cup serving of raw to cooked beet greens, you gain more nutrients from the cooked version.