The correct answer is A, parathyroid gland.
The parathyroid hormone is secreted by the parathyroid gland which <span>inhibits osteoblasts, stimulates osteoclasts,</span> reduces the calcium output by the kidneys and promotes absorption of the calcium by the small intestines. Calcitonin, secreted by the thyroid gland, also works to a similar effect.
Fatigue in skeletal muscles typically develops during repeated shortening contractions, as during walking or running. However, most experimental fatigue studies have analysed isometric muscle contractions, were the muscle generates force at a constant length.
The cell membrane functions as a selective barrier. We call these kind of membranes as differentially permeable or semi permeable membrane. It can decide what substances can pass in and out. Therefore it can surround the cytoplasm (which is the inside of a cell) to separate the cell's content from the surroundings.
