医学英语翻译

Unit1
The 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 curiously, it is not one that the average person wholeheartedly shares. Man’s attitude toward his own body—his single most precious possession—is 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 body 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 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 sees 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 from the same premise: an awareness of the body’s basic structure and functions—its 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 Specialists
Studies of the cell—what 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 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, which keeps the cell contents in and undesirable material out, yet permits passage of both proper nutrients and wastes. The nucleus—cell headquarters—governs the major activities of the cytoplasm; its finest hour, however, comes at reproduction time, when chromosomes containing DNA split. It is in the cytoplasm, that the cell’s 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 protein—along
with reproduction, 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。

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 the 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 kilter—in 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 body's cells develop specialized features and abilities. The cells that form bone collect calcium salts; these cells are locked together in solid chunks, 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 body's use—the hormones produced in the endocrine glands, or the digestive enzymes poured into the intestine from the pancreas. Still other 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 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 that 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 holds 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 body’s external coating—the skin—epithelial cells protect 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 free 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 hormon es that regulate the body’s 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、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 Overlap
The tissues comprise the structural materials of the body’s organ systems. These, in turn, may be compared to a number of corporations with interlocking directorates. Indeed the interdependence of the organ systems has led to some disagreement over how many there are. The venerable Gray’s Anatomy—used by medical students for more than 100 years—lists 10 systems: nervous, digestive, respiratory, vascular, urogenital, endocrine, skeletal, muscular, joints and external 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 urogenital—under the resounding title of splanchnological system.
人体器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 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 that 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". Variations 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 practitioner’s major headaches is to determine whether a pa tient’s 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 weight 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统计资料所确认的。

健康的心脏重量范围是240~360g，健康的肝脏重量在1000~2000g之间，血糖浓度水平是70~130mg。

Unit 2
Reading A
Human 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 to 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 anatomy.
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 and 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 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, while 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 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 united 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 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 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 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。

心脏大概两个拳头则大，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 pumped 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) 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。

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 thyroid gland, for example, secrets thyroxin ,which controls the rate at which energy is produced（the metabolic rate）.
心血管系统也参与运输一些由内分泌系统的腺体分泌且直接进入血浆的
激素。

这些激素控制身体的许多功能。

例如，甲状腺分泌甲状腺素，这种激素
控制着能量产生的速度（代谢率）。

The respiratory system starts at the nasal passage, where air is breathed in during inspiration. There the air is filtered and its temperature regulated. It passes through the larynx and trachea into the bronchi and bronchioles, and ends in little air pockets called alveoli within the lungs. The used blood is cleansed of carbon dioxide, which is expelled in the process known as expiration. The cleansed blood is then oxygenated and redistributed along the circulatory system. The entire process is called respiration and occurs at the rate of about 16 to 20 times per minute.
呼吸系统始于鼻腔通道，即吸气时空气进入的地方。

在那里（鼻腔）空气被过滤，温度被调节。

然后，空气通过喉和气管进入支气管和细支气管，最后进入肺部被称作肺泡的小气泡里面。

被用过的血液清除二氧化碳并通过呼气过程排出。

净化后的血液随后被氧化并且随着循环系统被重新分配。

这
整个过程称为呼吸，它发生的频率在每分钟16到20次之间。

The largest organ in the body is the outer covering called
Skin.(the average man about 20 square feet of it. ) The skin plus its associated structures (hair, nails, sebaceous and sweat glands, and specialized sensory receptors that enable the body to be aware of touch, cold, heat, pain, and pressure) make up the integumentary system. Skin protects the body from microbes and other impurities, prevents the loss of body fluids, and regulates body temperature. Three layers of tissue make up the skin-the epidermis, the dermis, and the subcutis (subcutaneous layer) The epidermis is in constant growth, with its outer layer of dead cells continuously being replaced as new cells are formed in the lower layer. Hair, fingernails, and toenails are specialized forms of epidermis. The coloring pigment called melanin is also found in the epidermis. The middle layer (or dermis) is the location for two main types of glands-sweat glands and oil glands. The innermost subcutis contains fat cells, blood vessels, and nerves.
人体最大的器官就是包裹在人体表层的皮肤（一般人的皮肤面积平均约为20平方英尺）。

皮肤加上与之相关的结构（头发，指甲，皮脂腺和汗腺，以及专门能使身体感受触摸，冷，热，痛苦和压力的感受器）共同组成了皮肤系统。

皮肤能保护机体免受微生物和其他杂质的伤害，防止体液流失，及调节体温。

三层组织组成皮肤--表皮，真皮，和皮下组织(皮下层)。

表皮是在不断增长的，在表皮下层新形成的细胞会不断地替代外层死亡的细胞。

头发，指甲和脚趾甲都是表皮的特化形式。

在表皮中也发现了被称为黑色素的着色色素。

中间层（或真皮层）是皮肤的两种主要腺体，汗腺和皮脂腺的所在地。

最里面的皮下组织包含脂肪细胞，血管和神经。

Another major body complex is the digestive system, which processes the food so that it can be used for energy. The process begins in the mouth, where food is chopped and crushed by the teeth. In the mouth, saliva, excreted by the salivary glands, provides enzymes that help to break down the food`s carbohydrates. This taking of food into the body for digestion is called ingestion.
另一个主要的身体复合体是消化系统，该系统对食物进行加工处理，以便食物能被作为能量使用。

该过程开始于口腔，食物被牙齿嚼碎和粉碎。

在口腔里，由唾液腺分泌的唾液提供的酶有助于分解食物中的碳水化合物。

这种为了消化而获取食物进入身体称为摄入。

After food has been chewed, it passes through the esophagus into the stomach. Peristaltic movements in the walls of the esophagus help push the food along the alimentary canal. The muscular walls of the stomach continue the mixing process while secreting hydrochloric acid from the glands in the stomach lining. After 30 minutes to three hours in the stomach, the food is converted into a semiliquid state and passes into the small intestine, a tube about 20 feet long located in the lower abdomen. Here, enzymes from pancreatic fluid and bile from the liver complete the digestive process. Nutrients are absorbed into the blood through the villi, which line the walls of the digestive organs. What cannot be absorbed is passed out through the large intestine as feces. Liquid wastes are eliminated through the urinary system. They are picked up by the blood and removed by the kidneys. From there they pass through the ureter, bladder, and urethra, and are excreted from the body as urine.
食物被嚼碎后经过食管进入胃。

食道壁的蠕动有利于把食物推向消化道中。

胃壁肌肉在此过程继续搅拌同时盐酸从胃粘膜中的腺体分泌出来。

在胃里经过30分钟—3小时，食物转换成半液体状态，进入小肠，一条长约20英尺长，位于下腹部的管道。

在这里，来自胰液的酶和来自肝脏的胆汁完成消化过程。

营养物质通过排列于消化器官壁的绒毛被吸收进血液。

那些不能被吸收的作为粪便通过大肠被排出。

液体废物通过泌尿系统被消除。

它们被血液带走，然后被肾移除。

从那里它们再经过输尿管，膀胱，和尿道，然后以尿的形式从身体排出。

Closely associated with the urinary system is the reproductive system，by which human life is carried on to future generations. Sperm cells are produced in the testicles of the male and ejaculated through the penis into the female vagina. The fertilization of the female’s ovum (egg) by the male’s sperm is called conception. It usually occurs
in one of the fallopian tubes, which the sperm reaches through active movement from the place of deposition. Normally, the fertilized egg then travels to the uterus where it becomes an embryo, is implanted, and develops for about 280 days (until childbirth）.
与泌尿系统紧密联系的是生殖系统，通过生殖系统人类生命得以世代延续。

精子细胞在男性睾丸里产生，并通过阴茎射精进入女性阴道。

女性的卵子与男性的精子结合叫做受精. 受精通常发生在其中一条输卵管中，精子从存放处通过主动的运动到达输卵管。

在正常情况下，受精卵接着游移到子宫，在此植入并变成胚胎，然后发育约280天左右（直至分娩）。

The nervous system controls all other systems and bodily movements. Nerves carry sensory impulses to the central nervous system and motor impulses from the central nervous system. Most impulses are those that control muscles. Sensory impulses affect the senses that enable human beings to feel, see, taste, and so forth.
神经系统控制着其他所有系统和身体运动。

神经将感觉冲动传至中枢神经系统，并将运动冲动从中枢神经系统传出。

大部分运动冲动控制着肌肉，而感觉冲动影响感官，这些感官能使人类去感知，去看，去品尝等等。

The nervous system is divided into the central nervous system (the brain and spinal cord) and the peripheral nervous system, which consist of the nerves that connect muscles and sensory organs with the central nervous system. The central nervous system is responsible for sending impulses to the voluntary muscles. The autonomic system, a part of the peripheral nervous system, regulates the involuntary muscles and organs
神经系统分为中枢神经系统（脑和脊髓）和周围神经系统，包括把肌肉和感觉器官与中枢神经系统连接起来的神经。

中枢神经系统负责把冲动传递给随意肌。

自主神经系统即周围神经系统的一部分，调节不随意肌和器官。

The brain is not only the most important component of the nervous system; it is also the controller of all bodily activities, thoughts, and emotions. It is composed of the pons, medulla oblongata, cerebellum,
and cerebrum. The cerebellum is the area of the brain that coordinates the voluntary muscles; the medulla oblongata controls the involuntary muscles; the pons is where many important nerves originate.
脑不仅是神经系统中最重要的组成成分，而且是躯体活动、思维和情感的控制者。

它由脑桥、延髓、小脑、大脑组成。

小脑是脑中协调随意肌的部位，延髓控制不随意肌，脑桥是许多重要神经的起源处。

It is the cerebrum that gives humans their ability to think, remember, and conceptualize. It is divided vertically into two halves known as the right and left hemispheres. The left hemisphere processes verbal functions, while the right hemisphere is involved in nonverbal activities and is the seat of human creativity. Many scientists believe that, in each individual, one of the two hemispheres is dominant, and that the individual has greater intellectual strength in the dominant hemisphere.
正是大脑赋予了人以思考，保持记忆和形成概念的能力。

它纵向可分为左右两个半球。

左半球处理语言功能，而右半球涉及非语言活动并且它是人类创造力的所在地。

很多科学家相信，在每个个体的两个大脑半球中有一个占优势的，并且那个占有优势的大脑半球有较大的智力潜能。

It is amazing how well each system functions and coordinates with other systems to enable humans to live, reproduce, and create.
令人感到神奇的是每个系统的功能以及各个系统之间的协调配合，使人类得以生活、繁殖和创造。

Unit3
Body defense mechanisms。