1、Unit1The Human complex A Never failing Source of Wonderment“ In my view, ” wrote Thomas Jefferson in 1814 , “no knowledge can be more satisfactory to a man that of his own frame, its parts, their functions and actions. ” Distinguished thinkers before and since Jefferson have held this belief, but cu
2、riously, it is not one that the average person wholeheartedly shares. Mans attitude toward his own bodyhis single most precious possessionis decidedly ambivalent. At one and the same time he is fascinated by it and fearful of it, partly in echo of ancient taboos, partly in the conviction that the bo
3、dy is too complicated to understand.“在我看来， ”托马斯杰佛逊于 1814 年写道：“对人来说，没有什么知识会比了解自身的架构、部件、以及他们的功能和运动更能使他满足。 ”在杰佛逊前后的杰出思想家均持有这个观点，但激发人好奇心的是，这个观点并不为普罗大众所由衷地接受。人们对自己的身体（这个对他自身来说最为宝贵的财富）的态度其实是充满矛盾的。一方面，人们对身体感到非常着迷，另一方面，却又对其深感敬畏，这在一定程度上是受古代禁忌的影响，也在一定程度上反映了人们确信肉体过于复杂而难以理解。The possible approaches to a study of
4、 the body are legion. To the cynic, the body is no more than a tenement of clay; to the poet, a palace of the soul; to the physician, an all-too-ailing hulk. The psychiatrist sees it as a housing for the mind and personality. The geneticist sees it as a perpetuator of its own kind. The biologist see
5、s it as an organism which can alter the future as a result of the experience of the past.研究人体的方法可谓纷繁多样。对愤世嫉俗者来说，人体贱如粘土陋室；对吟诗作赋者来说，人体尊如灵魂的宫殿；对内科医生来说，人体是脆弱多病的躯壳。精神病学家视其为理智和个性的居所。遗传学家当其为自我繁衍的机器。生物学家视其为能借过往的经验来改变未来的生命体。All the specialized scientific views of the body are valid. All, however, must start
6、from the same premise: an awareness of the bodys basic structure and functionsits anatomy and physiology. And the bedrock principle of our present understanding of the body is that all living matter is composed of cells basically similar in structure and function.所有有关人体的专业科学的观点都是有依据的，然而，所有的这些都必须有同一个
7、前提：那就是对研究人体的基本结构和功能的解剖学和生理学的认识。我们对身体的了解的基本原则是，所有生物都是由结构和功能基本相似的细胞构成的。A Swarm of Tiny SpecialistsStudies of the cellwhat it is , what it does and how it reproduces itself have revealed it to be a fantastically complex world in itself. One of the major wonders of the cell is the disparity between its
8、minuteness and the prodigiousness of its activity. Each cell is so tiny that millions of them may be found in a half-inch cube of human body tissue. Yet each comprises an almost unimaginably busy chemical laboratory with a highly ordered division of labor.关于细胞的研究细胞是什么，它是干什么的和如何复制的已经表明细胞本身就是一个令人难以置信的
9、复杂世界。细胞的一大精妙之处在于其体积之微细与其活性之大之间的反差。每个细胞是如此渺小，以至于在一个半英寸立方体大小的人体组织中可能发现数以万计的细胞。然而，每个细胞都堪比一个繁忙到难以想象的并有着高度的分工的化学实验室。The cell has two main parts: a nucleus, containing the genetic material deoxyribonucleic acid (DNA), and a surrounding semifluid cytoplasm. Bounding the cytoplasm is the cell membrane, whic
10、h keeps the cell contents in and undesirable material out, yet permits passage of both proper nutrients and wastes. The nucleuscell headquartersgoverns the major activities of the cytoplasm; its finest hour, however, comes at reproduction time, when chromosomes containing DNA split. It is in the cyt
11、oplasm, that the cells day to day business is carried on. Each of its various components, or organelles, is a specialist of surpassing skill. One type breaks down the food given entry by the cell membrane and converts it into energy .Another provides the site for the synthesis of proteinalong with r
12、eproduction, a major function of most cells. Another packages the manufactured protein for transport wherever needed in the body.细胞有两个主要部分：含有遗传物质脱氧核糖核酸（DNA）的细胞核，以及周围呈半流质的细胞质。包围着细胞质的是细胞膜，它包含着细胞内容物,并将不需要的物质隔离在外，然而它允许营养物质和代谢废物通过。细胞核细胞的控制中心调控细胞质的主要活动；然而，它最美妙的时刻是当细胞分裂时，包含 DNA 的染色体分裂繁殖。细胞日复一日的工作是在细胞质中完成的。
13、各种组件或细胞器，都是一个个卓越的技术专家。其中一个功能是分解从细胞膜进入细胞的营养物质，并将其转化成能量。另一个功能是提供蛋白质合成的场所伴随着细胞复制的全过程，这是大多数细胞的主要功能。再一个功能是加工包装制造的蛋白质 ，并将其运输到身体所需的各个部位。To operate efficiently, the cell thus requires specific help from the body as a whole: food to provide raw material for the release of energy, oxygen to help break down th
14、e food, water to transport inorganic substances like calcium and sodium. Once its needs are satisfied, the cell itself provides the intricate mechanism for maintaining the balance essential to keep it in kilterin short, to keep the body alive and healthy.为了工作的高效运行，细胞需要得到身体的特定的帮助，总的来说：食物提供可释放能量的原材料，氧
15、气帮助分解食物，水用于运输无机物，比如钙、钠。一旦这些需要得到满足，细胞自身就会通过错综复杂的机制，来保持正常运作所必须的平衡确使身体处于正常状态简而言之，就是保持身体的活力和健康。Cells share certain common characteristics, but most of the bodys cells develop specialized features and abilities. The cells that form bone collect calcium salts; these cells are locked together in solid chun
16、ks, immobile. By contrast, the white cells of the blood, which fight off invading bacteria, roam freely about the body. Other cells make special chemicals for the bodys usethe hormones produced in the endocrine glands, or the digestive enzymes poured into the intestine from the pancreas. Still other
17、 cells form the incredibly thin membranes in the lung or kidney that permit the filtering or exchange of dissolved body fuels and wastes.细胞拥有一定的共性，但是大部分的人体细胞具有他们特化的特征和功能。那些构成骨的细胞能沉积钙盐，这些细胞连锁成坚固而无活动能力的块状固体。相比之下，血液中那些可以抵抗细菌侵略的白细胞，却能在身体内自由流动。某些细胞能产生特殊的化学物质供身体使用如内分泌腺产生的激素，由胰腺分泌并进入肠道的消化酶。还有些细胞在肺或肾脏形成非常薄的
18、膜，使其能够过滤或交换已被溶解的身体燃料和废物。According to their particular features and their intended functions, cells form different types of tissue: bone, muscle, blood, nerve tissue, connective tissue and epithelium. The cells that make up each of these are not identical, but belong together by reason of underlying
19、similarities. 根据它们各自的特点和所要求的功能，细胞形成不同种类的组织：骨、肌肉、血液、神经、结缔组织和上皮组织。构成这些组织的细胞是不同的，但因潜在的相似之处而同属一类。For example, the cells of bowel muscle are rounder and shorter than the long, spindly cells of leg muscle, yet both kinds contract forcefully when stimulated by a chemical or electrical impulse. The cells th
20、at make up bone tissue differ sufficiently to make brittle bone in one place and spongy, resilient cartilage in another, yet all store the salts which give bone its calcified structure. The loose network of cells that supports the fatty padding under the skin and the dense capsule of cells that hold
21、s the knee joint in place are both forms of connective tissue. All nerve cells, varied as they may be, receive and conduct electrochemical impulses. All blood cell, varied as they may be, float freely in a circulating fluid, plasma.例如，肠道的肌纤维比腿部细长的肌纤维更圆、更短，但是当这两种细胞都受到化学或电刺激时，它们都会发生强有力地收缩。构成骨组织的细胞是有相当
22、程度的不同，它们可以在一处形成脆骨，而在另一处形成疏松而有弹性的软骨；然而，所有的细胞能储存钙盐，使骨成为钙化的结构。支撑皮下脂肪的疏散网状细胞和维持膝关节在恰当位置的密集胶囊状细胞，都共同参与构成了结缔组织。尽管可能有所不同，所有的神经细胞都能接受并传导电化学冲动；尽管可能有所不同，所有的血细胞都能在循环流体血浆中自由地漂浮。The most versatile cells are those of the various kinds of epithelium. Forming the bodys external coatingthe skinepithelial cells prote
23、ct things inside from things outside. They also form the lining of the mouth, stomach and bowel, the inner surface of blood vessels, and the membranes that permit the lungs to breathe and the kidneys to excrete. Over the cornea of the eye they become a sort of transparent windshield, to permit the f
24、ree entry of light to the retina. Other epithelial cells secrete a protective mucus to keep intestines, lungs and nasal passages from drying out. Still others manufacture powerful hormones that regulate the bodys chemical reactions. 最万能的细胞是各种各样的上皮细胞。它们共同构成人体的外套皮肤，上皮细胞保护皮肤里面的物质不受外界侵害。它们还构成口腔、胃黏膜、肠黏膜、
25、血管内皮和参与肺呼吸以及肾排泄的膜。 覆布于眼角膜上的上皮细胞，它们变成一种透明的挡风玻璃，使得光束自由地进入到视网膜。其他的上皮细胞分泌保护性的粘液保持肠、肺和鼻腔不至于变干燥。还有一些上皮细胞能够产生高效能的激素来调节人体化学反应。Interlock and OverlapThe tissues comprise the structural materials of the bodys organ systems. These, in turn, may be compared to a number of corporations with interlocking directora
26、tes. Indeed the interdependence of the organ systems has led to some disagreement over how many there are. The venerable Grays Anatomyused by medical students for more than 100 yearslists 10 systems: nervous, digestive, respiratory, vascular, urogenital, endocrine, skeletal, muscular, joints and ext
27、ernal covering. Other authorities categorize joints and bones together because they are so closely related, or separate the sense organs from the nervous system, or lump all the internal organs respiratory, digestive, endocrine and urogenitalunder the resounding title of splanchnological system. 人体器
28、官系统的物质结构由组织组成。换言之，这就像互相之间交叉任职的董事的若干公司。事实上这些相互依赖的器官系统在他们数量多少的问题上也曾引发了一些争论。备受推崇的 Gray 解剖学-曾被被医学生使用了上百年的时间-列举出了十个系统：神经系统，消化系统，呼吸系统，血管系统，泌尿生殖系统，内分泌系统，骨骼系统，肌肉系统，关节和皮肤系统。而另一些权威人士则因关节和骨头是密不可分的而将他们归为一类，或是将感觉器官从神经系统分离出来，或是将所有的内脏器官-呼吸器官，消化器官，内分泌器官以及泌尿器官混在一块，冠以内脏系统这一声势浩大的名称。Far more important than their labels
29、 is the fact that the systems interact; the breakdown of one can damage or destroy the others. Ideally, of course, all systems would do their jobs perfectly all the time. Unfortunately, nature permits no such perfection. All of them suffer from malfunctions at one point or another. The wonder is tha
30、t breakdowns are the exception rather than the rule. 然而比给他们的命名更为重要的是他们各个系统之间会相互影响这个事实，其中一个系统的衰弱可以损害或毁灭其他系统。当然，理想状态下，所有的系统都是能一直完美地执行他们的任务的。而不幸的是，自然状态下是不可能出现这么完美的情况的。在所有系统当中，他们总会因这个方面或那个方面的故障而受到损害。神奇的是，出现故障倒是例外而不是常规情况Within the healthy body itself there is no absolute criterion for “normal“. Variation
31、s occur not only between individuals, but within the individual himself, sometimes from hour to hour, depending on his activity at the time. Doctors privately joke that even a baboon could get through medial school if he learned to say, with enough profundity, “It varies.“ One of the practitioners m
32、ajor headaches is to determine whether a patients condition reflects an actual illness or merely a variation within a broad range of normal. The breadth of this range may be indicated by a few statistics. The weight of the healthy heart is considered to be anywhere between 240 and 360 grams; the wei
33、ght of the healthy liver, between 1,000 and 2,000 grams; the level of sugar in the blood, between 70 and 130 milligrams.在健康的人体内对于“正常” 也没有确切的标准可言。变化不仅仅发生在个体之间，也可以发生在个体内部，有时候每个小时都不同，这要看他们当时的运动状态。医生私下开玩笑说，即使是一个狒狒，它也可以在医学院校毕业，前提是他学会很深沉地说“因人而异” 。令从医者最头痛的问题之一就是要确认一个人的情况是真正生病了还是处于正常的变化范围之中。有些范围内的波动可能是已经被一些
34、统计资料所确认的。健康的心脏重量范围是 240360g，健康的肝脏重量在 10002000g 之间，血糖浓度水平是70130mg。Unit 2Reading AHuman Anatomy The human body is a remarkably complex and efficient machine. It takes in and absorbs oxygen through the respiratory system. Then the oxygen-enriched blood is distributed through the cardiovascular system t
35、o all tissues. The digestive system converts digestible food to energy and disposes of the rest. The skeletal-muscular system gives form to the body. And covering almost the entire mass is the skin, the largest organ of the body. The science of the structure of this complicated” machine” is called a
36、natomy.人体是一个非常复杂并且高效的机器。它通过呼吸系统吸入并且吸收氧气。然后这富含氧的血液通过心血管系统被分布到所有的组织。消化系统将能消化的食物转变成能量并且将剩余的废物排出。骨骼-肌系统组成了人体的轮廓。全身最大的器官皮肤,几乎覆盖整个躯体。这门研究机体复杂构造的科学被称为“解剖学 ”One of the major systems is the skeletal-muscular system. The body is supported and given shape by this structure, consisting of more than 200 bones an
37、d the muscles and tendons which are connected to them. They are strong but can bend at their joins. They also serve as a shield, protecting the vital internal organs from injury.主要的系统之一是骨骼-肌系统。人体由这个结构作支撑并构成形态，这一结构由 200 多块骨和肌肉及与之相连的肌腱组成。它们很坚固但是能够通过弯曲关节。它们也能像防护物一样，保护内部重要的器官免受伤害。Bones are as strong as
38、steel but much lighter and more flexible. They are composed of minerals, organic matter, and water, held together by a cement-like substance called collagen, and are filled with red and yellow bone marrow. The red marrow produces the red blood cells used throughout the body to transport oxygen, whil
39、e the yellow marrow consists of fat cells. A tough membrane called the periosteum covers most of the bone surface and allows bones to be nourished by blood.人体的骨骼像钢铁一样坚韧但是骨骼更轻更柔韧。这些骨骼由矿物质，有机物，水构成-它们通过一种被称为胶原的类似结合剂的物质连结起来，并且充满了红骨髓和黄骨髓。红骨髓产生一种能够运输氧气到达全身各处的血红细胞，然而黄骨髓由脂肪细胞组成。有一种坚韧的膜被称为骨膜，它覆盖了大部分骨的表面，使骨头能
40、得到血液的滋养。A major bone structure in the body is the vertebral (spinal) column. It runs up and down the back and protects the spinal cord, where many of the major nerves are located. It is composed of bony vertebrae which are held together by ligament of connective tissue and separated from each other
41、by spinal discs. At the top of the vertebral column is the skull, which surrounds and protects the brain. Attached to the vertebral column below the neck are the 12 pairs of ribs, comprising the rib cage. At the bottom is the sacrum, which connects the vertebral column to the pelvis. Bones are unite
42、d by joints and held together by ligaments.身体中一个主要的骨骼结构是脊柱。它贯穿人体背部并且保护脊髓，有很多重要的神经位于这里。脊柱是由属于结缔组织的韧带连接起来的椎骨组成的，并且相邻椎骨由椎间盘分隔开。在脊柱的顶部是颅骨，颅骨包裹并且保护脑。在颈部以下连着脊柱的是 12 对肋骨，共同构成了胸廓。脊柱的底部是骶骨，骶骨把脊柱和骨盆连接在一起。骨骼通过关节联合并且通过韧带连结。Muscles are special fibrous tissues found throughout the body. They control movement and
43、many organic functions by contracting in response to nerve signals. Skeletal muscles are called voluntary because they can be consciously controlled. They are attached to bones by tough fibrous tissues called tendons. Other muscles, such as the stomach muscled and the heart, are involuntary and are
44、operated automatically by the central nervous system.肌肉是遍布身体的特殊纤维组织。它们通过收缩来回应神经信号从而控制运动和许多器官功能. 骨骼肌能被意识控制，所以称为随意肌。它们通过一个叫肌腱的结实纤维组织紧紧附着于骨上。其他肌肉，例如胃肌和心肌，都是非随意肌，由中枢神经系统控制，自动运作.The most important muscles in the body is the heart. Without the heart and its cardiovascular (circulatory) system, human life
45、would not be possible. The heart is roughly the size of two fists. It contracts at an average rate of 72 times per minute or nearly 38,000,000 times a year. These rhythmic contractions are called the pulse rate and can be felt in the radial artery of the wrist. 心肌是人体最重要的肌肉，没有心肌和它的心血管循环系统，人类将不可能生存。心脏
46、大概两个拳头那么大，平均每分钟收缩 72 次或接近 38000000 次每年。这种有节奏的收缩称之为脉搏, 并且可以在手腕的桡动脉处感觉到。The human heart consists of four chambers ，two atria and two ventricles .Each is made up of several layers of cardiac muscles arranged in circles and pirals. During the contraction phase, called the systole, oxygenated blood is pu
47、mped out of the left ventricle into the aorta and from there through the arteries to all organs of the body. Carbon dioxide, a waste product of this process ,is collected in the blood. The blood is passed back to the right atrium through the veins and the vena cava during the diastole (or relaxation
48、) period of the heart. From there, it is pumped into the right ventricle and to the pulmonary artery to be sent to the lungs where carbon dioxide is removed and oxygen is added.人的心脏由四个腔室组成, 两个心房和两个心室, 每个腔都是由许多层心肌环绕，盘旋排列而成。 （心脏）在收缩阶段，被称为收缩期，富含氧的血液从左心室泵出进入主动脉，然后从那里通过动脉运送到全身所有的器官。二氧化碳是这个过程中产生的废物，通过血液收集
49、。血液在心脏舒张期通过静脉和腔静脉回流到右心房。从那，血液被泵入右心室并通过肺动脉被送到肺部，在那二氧化碳被移除，氧气被加入。The rest of the system consists of arterioles (small arteries), venules (small veins), and capillaries, the smallest of blood vessels. In total, there are more than 70000 miles of blood vessels in the human body!这个（心脏）系统的其余部分则是由小动脉，小静脉及最微小的血管毛细血管构成，总的来说，人体中的血管长度远远超过70000英里！The cardiovascular system also carries hormones which are secreted by glands of the endocrine system directly into the bloodstream. These hormones control many functions of the body. The
