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Hypocalcemia (low blood calcium) and hypercalcemia (high blood calcium) are both serious medical disorders. Osteoporosis, osteomalacia and rickets are bone disorders linked to calcium metabolism disorders and effects of vitamin D. Renal osteodystrophy is a consequence of chronic kidney failure related to the calcium metabolism.
Physiological bone resorption is an integral part of bone functioning, while the bone is constantly growing thanks to two processes — breakdown and formation of bone tissue. [23] Locally, it could be manifested in tooth eruption when the movement of a tooth follicle is followed by an active resorption of jaw bone tissue.
When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism. [3] However, maturation, activation, and some proliferation of lymphoid cells occurs in the spleen, thymus, and lymph nodes. In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia.
Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. [2] In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). [3] It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells.
Atrophic non-union results in re-absorption and rounding of bone ends [6] due to inadequate blood supply and excessive mobility of the bone ends. [4] Mal-union: healing occurs but the healed bone has 'angular deformity, translation, or rotational alignment that requires surgical correction'. This is most common in long bones such as the femur.
Absorption of dietary iron in iron salt form (as in most supplements) varies somewhat according to the body's need for iron, and is usually between 10% and 20% of iron intake. Absorption of iron from animal products, and some plant products, is in the form of heme iron, and is more efficient, allowing absorption of from 15% to 35% of intake.
Diagram of a typical long bone showing both cortical (compact) and cancellous (spongy) bone. Haversian canals [i] (sometimes canals of Havers, osteonic canals or central canals) are a series of microscopic tubes in the outermost region of bone called cortical bone. They allow blood vessels and nerves to travel through them to supply the osteocytes.
Single photon absorption is the earliest method to measure bone mineral density accurately. Its basic principle is that bone mineral density can be obtained by the law of absorption. In this law, the important parameters to be obtained are bone thickness, bone absorption coefficient and radiation intensity (or counting) after bone absorption.