Passage one The Skeletal System骨骼系统
Without the skeletal system we would be unable to perform movements, such as walking or grasping. The slightest jar to the head or chest could damage the brain or heart. It would even be impossible to chew food. The framework of bones and cartilage that protects our organs and allows us to move is called the skeletal system.没有骨骼系统我们不会完成运动，如行走或抓握。轻微的撞击头部或胸部就会损伤头部或心脏。它会甚至不能咀嚼食物。骨和软骨的框架下保护我们的器官中，让我们可以继续被称为的骨骼系统。
Functions. The skeletal system performs veral basic functions.功能。骨骼系统执行几个基本功能。
◆ Support: the skeletal system provides a framework for the body and, as such, it supports soft tissues and provides a point of attachment for many muscles.支持：骨骼系统，提供了一个框架，用于身体的，同样，它支持软组织的位置时，为客户提供许多的肌肉。
◆ Protection: many internal organs are protected from injury by the skeleton. For example, the brain is protected by the cranial bones, the spinal cord by the vertebrae, the heart and lungs by the rib cage, and internal reproductive organs by the pelvic bones.保护：许多内脏免受伤害骨架。例如，大脑是颅保护骨头、脊髓的脊椎，心脏和肺的肋骨，和内部的生殖器官骨盆骨的。
lori◆ Movement: bones rve as levers to which muscles are attached. When the muscles contract, the bones acting as levers produce movement.骨头运动:◆作为杠杆来肌肉附呈。当肌肉收缩，骨骼作为杠杆生产运动。
◆ Mineral storage: bones store veral minerals that can be distributed to other parts of the body on demand. The principal stored minerals are calcium and phosphorus.矿产贮存:◆骨头商店可以多种矿物质分发给身体的其他部分有求必应。校长储存矿物质是钙和磷的含量。
◆ Blood cell production: red marrow in certain bones is capable of producing blood cells, a process called hematopoiesis or hemopoiesis. Red marrow consists of blood cells in immature stages, fat cells, and macrophages. Red marrow produces red blood cells, some white blood cells and platelets.◆血细胞生产：红色的骨髓在某些骨头能产下血细胞，这个过程称为造血或hemopoiesis。红色的骨髓由血细胞在不成熟的阶段，脂肪细胞和巨噬细胞。红色的骨髓产生红血球，有些白血球和血小板。
Types of bones. Almost all of the bones of the body may be classified into four principal types on the basis of shape: long, short, flat and irregular. Long bones have greater length than width and consist of a diaphysis and a variable number of epiphys. For example, metacarpals, metatarsals, and phal
anges have only one epiphysis. The femur actually has four. Other long bones have two.类型的骨头。几乎所有的身体的骨头可分为四个主要
类型的基础上，形状：长的、短的、公寓、不规则的。长骨有更大的漫长而不是宽度和包括骨干和一个可变数目的epiphys。例如,metacarpals、蹠骨，和趾骨只有一个epiphysis。股骨却有四个。其他长骨生两个
Long bones are slightly curved for strength. A curved bone is structurally designed to absorb the stress of the body weight at veral different points so the stress is evenly distributed. If such bones were straight, the weight of the body would be unevenly distributed and the bone would easily fracture. Examples of long bones include bones of the thigh, legs, toes, arms, forearms, and fingers.长骨头稍弯曲以增加强度。弯曲的骨结构的应力专用于吸收体重不同的点的应力是均匀分布。如果这样的骨头就直，机身重量，将分配不均和骨很容易骨折。长骨干的例子包括大腿的骸骨、腿，脚趾、手臂、前臂和手指。
Short bones are somewhat cube-shaped and nearly equal in length and width. Their texture is spongy except at the surface, where there is a thin layer of compact bone. Examples of short bones are the wrist and ankle bones.有些短骨方形和近有着同样的长度和宽度。他们的质地松软的除了在表面，哪里有一层薄薄的紧凑的骨头。短的例子骨头手腕和脚踝的骨头。
薯条的英文Flat bones are generally thin and compod of two more or less parallel plates of compact bone enclosing a layer of spongy bone. Flat bones afford considerable protection and provide extensive areas for muscle attachment. Examples of flat bones include the cranial bones(which protect the brain), the sternum and ribs(which protect organs in the thorax), and the scapulae.扁骨一般瘦，由两个或多或少的小骨附上平行板一层发泡骨。扁骨负担得起相当大的保护和提供广阔的地域肌肉附件。扁骨的例子包括颅骨头(保护大脑)，胸片和肋骨保护器官(开始),scapulae。
八年级英语教案
Irregular bones have complex shapes and cannot be grouped into any of the three categories just described. They also vary in the amount of spongy and compact bone prent. Such bones include the vertebrae and certain facial bones.不规则骨有较复杂的外形和不能被分成三大类的了。他们也不同数量的发泡而简洁的骨礼物。这些骨头包括椎骨和一定的面部的骨头。
There are two additional types of bones that are not included in this classification by shape. Sutural or wormian bones are small bones between the joints of certain cranial bones. Their number varies greatly from person to person. Sesamoid bones are small bones in tendons where considerable pressure develops, for instance, in the wrist. The, like sutural bones, are also variable in number. Two samoid bones, the patellas (kneecaps), are prent in all individuals.有两个额外的类型的骨头，不包括在这分级的形状。wormian针脚或骨头小骨头关节之间的某些颅的骨头。他们
的数目人来说是不相同的。Sesamoid的骨头小骨肌腱相当大的压力在发展，例如，在手腕。这些如同针脚骨头，也变多。两samoid超负荷的骨头,patellas()，存在于所有的个体。
Bone replacement. Bones undergoing either intramembranous or endochondral ossification are continually remodeled from the time that initial calcification occurs until the final structure appears. Remodeling is the replacement of old bone tissue by new bone tissue. Compact bone is formed by the transformation of spongy bone. The diameter of a long bone is incread by the destruction of the bone clost to the marrow cavity and the construction of new bone around the outside of the diaphysis. However, even after bones have reached their adult shapes and sizes, old bone is perpetually destroyed and new bone tissue is formed in its place. Bone is never metabolically at rest; it constantly remodels and reappropriates its matrix and minerals along lines of mechanical stress.骨更换。intramembranous或endochondral接受或骨骨化常帮自从初始钙化直到最后结构出现。重建旧的是将由新骨组织骨组织。紧凑的骨形成的转型发泡骨。直径长骨被破坏了我的骨头骨髓腔最近，为建设新骨外线超越了骨干。然而，即使是在成人已经达到他们的骨头形状和大小，老骨头被毁，永远是新生骨形成组织是在自己的地方。骨从不新陈代谢的作用，在休息，本公司不断重新改型和reappropriates它的矩阵里沿着线和矿物质机械应力。
Bones shares with skin the feature of replacing itlf throughout adult life. Remodeling takes place at 高傲的英文
faminedifferent rates in various body regions. The distal portion of the femur (thighbone) is replaced about every 4 months. By contrast, bone in certain areas of the shaft will not be completely replaced during the individual’s life. Remodeling allows worn or injured bone to be removed and replaced with new tissue. It also allows bone to rve as the body’s storage area for calcium. Many other tissues in the body need calcium in order to perform their functions. For example, a nerve cell needs calcium for nerve impul conduction, muscle needs calcium to contract, and blood needs calcium to clot. The blood continually trades off calcium with the bones, removing calcium when it and other tissues are not receiving enough of this element and resupplying the bones with dietary calcium to keep them from losing too much bone mass.骨头的特点与肌肤股票取代本身在适应成年人的生活作好准备。重构以不同的比率发生在不同的身体地区。远端部分股骨(病症)代替大约每4个月。相比之下，骨头的某些区域轴就不可能完全取代了经个人的生命。重塑允许穿或受伤的骨头被拆卸和更换新组织。它也允许骨作为人体的区域存放的钙。许多其他组织的身体需要钙为了完成他们的功能。例如，一个神经细胞需要钙质,
使肌肉神经冲动传导需要钙合同，和血液需要钙质血块。不断地交易的血钙与骨了的时候，消除钙和其他组织都没有得到足够的这个元素和补给作战骨钙与饮食，使他们免遭失去太多的骨骼。
The cells believed to be responsible for the resorption (loss of a substance through a physiological o
r pathological process) of bone tissue are osteoclasts. In the healthy adult, a delicate homeostasis is maintained between the action of the osteoclasts in removing calcium and the action of bone-making osteblasts in depositing calcium. Should too much new tissue be formed, the bones become abnormally thick and heavy. If too much calcium is deposited in the bone, the surplus may form thick bumps, or spurs, on the bone that interferes with movement at joints. A loss of too much tissue or calcium weakens the bones and allows them to break easily or to become very flexible. A greatly accelerated remodeling process results in a condition called Paget’s dia.
这些细胞被认为是负责吸收(亏损的物质通过的生理或病理过程中骨组织是破骨细胞。在健康的成年人，一个精致的稳态关键之间保持破骨细胞的作用除钙和作用的存款osteblasts bone-making钙。应该太多形成新组织，骨头变得异常很厚实。如果太过于钙沉积在骨的贸易顺差可能形成厚撞击，与马刺，骨头上的运动，它会妨碍到关节。失去太多的组织或钙削弱的骨头，并允许他们易碎，或是想成为高度的灵活性。一个极大地加速过程重构的结果名为帕哲病的症状，条件。
英语翻译In the process of resorption, it is believed that osteoclasts nd out projections that crete protein-digesting enzymes relead from lysosomes and veral acids (lactic and citric). The enzymes may function by digesting the collagen and other organic substances, while the acids may cau the bone salts (minerals) to dissolve. It is also presumed that the osteoclastic projections may phagocyto
whole fragments of collagen and bone salts. Magnesium deficiency inhibits the activity of osteoclasts.
吸收的过程中，据说破骨细胞发出后,protein-digesting释放分泌酶溶酶体和几个酸(乳酸和柠檬)。消化的酶可能功能的胶原质及其他有机物质，而酸可以使骨盐(矿物质溶解。它也是假定那骨质预测可能phagocyto整个碎片的胶原蛋白和骨盐。缺乏镁抑制破的活动。
Normal bone growth in the young and bone replacement in the adult depend on veral factors. First, sufficient quantities of calcium and phosphorus, components of the primary salt that makes bone hard, must be included in the diet. Mangane may also be important in bone growth. It has been shown that mangane deficiency significantly inhibits laying down new bone tissue.
Second, the individual must obtain sufficient amounts of vitamins, particularly vitamin D, which participates in the absorption of calcium from the gastroint日语新年快乐怎么说
estinal tract into the blood, calcium removal from bone, and kidney reabsorption of calcium that might be otherwi be lost in urine.正常骨生长在年轻的和骨置换在成人取决于几个因素。首先，足够数量的钙、磷、部件的主要盐使骨硬，必须包含在饮食。锰可能也有重要的骨骼生长。有证据表明，锰缺陷显著抑制躺新骨组织。其次，每个人都必须获得足够的大量的维生素，尤其是维他命D，它参
与吸收钙从胃肠道进入血液、钙的清除、肾重吸收变化骨钙，可能是其他迷失在尿液。
leadtoThird, the body must manufacture the proper amounts of the hormones responsible for bone tissue activity. Growth hormone (GH) creted by the pituitary gland, is responsible for the general growth of bones. Too much or too little of this hormone during childhood makes the adult abnormally tall or short. Other hormones specialize in regulating the osteoclasts. Calcitonin (CT), produced by the thyroid gland, inhibits ostoclastic activity and accelerates calcium absorption by bones, while parathormone (PTH ), synthesized by the parathyroid glands, increas the number and activity of osteoclasts. PTH also releas calcium and phosphate from bones into blood, transports phosphate from blood into urine. And still others, especially the x hormone, aid osteoblastic activity and thus promote the growth of new bone. The x hormones act as a double-edged sword. They aid in the growth of new bone, but they also bring about the degeneration of all the cartilage cells in epiphyal plates. Becau of the x hormones, the typical adolescent experiences a spurt of growth during puberty, when x hormone levels start to increa. The individual then quickly completes the growth process as the epiphyal cartilage disappears. Premature puberty can actually prevent one from reaching an average adult height becau of the simultaneous premature degeneration of the plates.美联航弄坏吉他
onceagain第三，身体必须制造适当的大量的荷尔蒙负责骨骼组织的活动。生长激素(GH)由脑垂体分泌，负责一
般生长骸骨。过多或过少的这种激素在儿童时期使成人异常高或短。其它植物激素的破专业规范。降钙素(CT)，所生产的甲状腺ostoclastic活动和加速，可抑制也钙质吸收，而甲状旁腺激素摘要镀通孔、合成而甲状旁腺，增加了和活动、破骨细胞。也可以释放一部分钙和磷镀通孔失效从骨头变为血、运输钙血流在尿液。还有些人，特别是性激素，援助，故成骨的促进生长的新生骨。性荷尔蒙作为双刃剑。他们帮助的新生骨，而他们也带来的所有的退化在epiphyal软骨细胞板。因为性激素，典型的青少年，经历了一股增长青春期，当性激素水平开始增加。个人就完成的成长过程中epiphyal软骨消失了。过早青春期确实能预防一个成年人平均到达高度因为同时过早贬低的这些盘子。
Aging and the skeletal system.
