bone Rigid connective tissue of vertebrates, consisting of cells embedded in a hard matrix. Bones serve as the body’s supporting framework, pro¬ vide muscle-attachment points for movement, protect the internal organs, house the blood-cell formation system (red bone marrow), and hold about 99% of the calcium vital to many body processes. Bone consists of a matrix of crystals of calcium, chiefly the phosphate and carbonate, embed¬ ded among collagen fibres, providing strength and elasticity, and bone cells (less than 5% of its volume). An external layer of compact bone sur¬ rounds a central area of spongy bone, except at the marrow cavity. Bone does not grow by cell division; instead, different types of bone cells gen¬ erate bone matrix, break it down, and maintain it. Bone is remodeled by this process, which strengthens it in areas under greatest stress, permits healing of fractures, and helps regulate calcium levels in body fluid (see
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physis (growth plate) epiphysis compact bone
Haversian
Volkmann
canal
periosteum
osteocyte
cancellous (spongy) bone
cancellous (spongy) bone
compact bone
medullary containing marrow
periosteum-
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Haversian
canal
Internal structure of a human long bone, with a magnified cross section of the inte¬ rior. The central tubular region of the bone, called the diaphysis, flares outward near the end to form the metaphysis, which contains a largely cancellous, or spongy, interior. At the end of the bone is the epiphysis, which in young people is separated from the metaphysis by the physis, or growth plate. The periosteum is a connective sheath covering the outer surface of the bone. The Haversian system, consisting of inorganic substances arranged in concentric rings around the Haver¬ sian canals, provides compact bone with structural support and allows for metabo¬ lism of bone cells. Osteocytes (mature bone cells) are found in tiny cavities between the concentric rings. The canals contain capillaries that bring in oxygen and nutri¬ ents and remove wastes. Transverse branches are known as Volkmann canals.
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Bone ► Bonn I 247
calcium deficiency). The process also causes underutilized bone, as in an immobilized limb, to atrophy. Bone disorders include rheumatoid arthritis, osteoarthritis, rickets, osteoporosis, and tumours. Bone can fracture sud¬ denly or over time, as in stress fractures.
Bone See Annaba
bone china Hard-paste porcelain containing bone ash. It was developed by Josiah Spode (1754-1827) in England c. 1800. The addition of bone ash to china stone and china clay (i.e., hard china) made bone china easier to manufacture; it is stronger, does not chip easily, and has an ivory-white colour that lends itself to decoration. Other factories (Minton, Derby, Worcester, Wedg¬ wood, Rockingham) adopted the for¬ mula in the early 19th century. Bone china remains popular for tableware in Britain and the U.S. See also STONEWARE.
bone marrow or myeloid tis¬ sue Soft, gelatinous tissue that fills bone cavities. Red bone marrow con¬ tains stem cells, progenitor cells, per- cursor cells, and functional blood cells (see reticuloendothelial system). Lymphocytes mature in the lymphoid organs (see lymphoid tissue). All other blood-cell formation occurs in red marrow, which also takes part in destruction of old erythrocytes (red blood cells). Yellow bone marrow mainly stores fats. Because the leukocytes (white blood cells) produced in bone marrow are involved in immune defenses, marrow transplants can treat some types of immunodeficiency. Radiation and some anticancer drugs can damage marrow and impair immunity. Bone-marrow examination helps diagnose diseases related to blood and blood-forming organs.
bonefish Marine game fish ( Albula vulpes) that inhabits coastal and island waters in tropical seas and is admired by anglers for its speed and strength. Its maximum length is about 30 in. (76 cm), and its maximum weight is 14 lbs (6.4 kg). The bonefish has a deeply notched caudal fin (near the tail) and a small mouth beneath a pointed, piglike snout. It grubs on the bottom for worms and other food.
bongo Large, brightly coloured antelope ( Boocercus , or Taurotragus, eurycerus) found in dense forests of central Africa. Shy, swift, and elu¬ sive, the bongo lives in small groups or in pairs. It stands about 51 in. (1.3 m) at the shoulder and has an erect mane running the length of the back.
Both sexes bear heavy, spirally twisted horns. The male is reddish brown to dark mahogany with black underparts, black-and-white legs, white head markings, and narrow, vertical white stripes on the body.
The female is similarly marked but usually a brighter reddish brown.
Bonheur \ba-'nor\, Rosa (b. March 16, 1822, Bordeaux, France—d. May 25, 1899, Melun) French animal painter. She was trained by her father, an art teacher, and began exhibiting regularly at the Paris Salon in 1841. Her unsentimental paintings of lions, tigers, horses, and other ani¬ mals became very popular; The Horse Fair (1853) gained her an inter¬ national reputation. A colourful personality, she dressed as a man to study horses at the actual Horse Fair in Paris, receiving formal permission from the police to do so. In 1865 she became the first woman to receive the Grand Cross of the Legion of Honour.
Bonhoeffer Vbon- 1 hoe-f3r\ / Dietrich (b. Feb. 4, 1906, Breslau, Ger.—d. April 9, 1945, Flossenbiirg) German Lutheran pastor and theo¬ logian. He attended the Universities of Berlin and Tubingen, and from 1931 he lectured in theology at the University of Berlin. He became a leading spokesman for the Confessing Church and was active in the resis¬ tance movement under the guise of employment in military intelligence. He was arrested and imprisoned in 1943. The discovery of documents
connecting him with the 1944 attempt on Adolf Hitler’s life led to his execution a month before the end of World War II. One of the most insightful theologians of the 20th century, he argued for a new vision of Christianity that would abolish the division between the sacred and pro¬ fane and abandon the traditional privileges of the church in favour of active involvement in the world’s problems. His best-known works include The Cost of Discipleship (1937), Ethics (1949), and Letters and Papers from Prison (1951).
Boniface Vba-no-fosV Saint (b. 675, Wessex, Eng.—d. June 5, 754, Dokkum, Frisia; feast day June 5) English missionary and reformer. Origi¬ nally named Wynfrith, he became a Benedictine monk and then a priest. He made two attempts to convert the Frisian Saxons; in 718 he journeyed to Rome, where Pope Gregory II entrusted him with a mission to the pagans east of the Rhine and gave him the name Boniface. In 722 at Hesse he founded the first of many Benedictine monasteries. He was active for 10 years (725-735) in Thuringia. He established four bishoprics in Bavaria, paving the way for its incorporation into the Carolingian empire. He convened five synods (740-745) to reform the Frankish clergy and Irish missionaries and a council (747) to reform the entire Frankish king¬ dom. He was killed by a band of Frisians while reading the Bible to recent converts.
Boniface of Querfurt, Saint See Saint Bruno of Querfurt
Boniface VIII orig. Benedict Caetani (b. c. 1235, Anagni, Papal States—d. Oct. 11, 1303, Rome) Pope (1294-1303). Bom into an influ¬ ential Roman family, Caetani studied law in Bologna and rose through the papal government to become cardinal-deacon (1281) and pope. In 1296 his attempt to end hostilities between Edward I of England and Philip IV of France became embroiled in the issue of taxation of clergy without papal consent. When Boniface issued a bull forbidding such taxation, Philip fought back with economic measures. They clashed again in 1301 over control of the clergy when Philip had a French bishop tried and imprisoned. Eventually, hearing that Boniface planned to excommunicate Philip, Philip’s supporters captured the pope; though rescued two days later, he died shortly thereafter.