医学英语(阅读一分册)翻译及答案(2)

微米，肉眼勉强可以看得到，不需要显微镜的帮助。

The study of cells is the branch of biology called cytology. The science that deals with cells on the smallest structural and functional level is called molecular biology. 研究关于“细胞”是生物学的分支，成为细胞生物学。在最微小水平针对细胞的结构及功能的研究成为分子生物学。 All cells consist of protoplasm, the “living jelly.” The protoplasm of a typical cell forms three vital parts----the cell membrane, the cytoplasm, and the nucleus. The membrane encloses the other cell structures. Much of the chemical work of the cell is done in the cytoplasm, which surrounds the nucleus. The nucleus, enclosed by its own membrane, is the control center of the cell. (see Figure 1-1) 所有细胞都是以“原生质”，又称“生命胶质”所形成的。典型细胞的原生质形成了三个重要部分，细胞膜、细胞质和细胞核。细胞膜圈住了细胞的其他结构。大部分的化学反应都在细胞核周围，细胞质完成的。被自己的膜包围的细胞核是细胞的控制中心。 the cells Membrane细胞膜

Cells can survive only in a liquid medium that brings in food and carries away waste. For one-celled organisms this fluid is an external body of water----the ocean, a lake, or a stream. For many-celled plants and animals, however, the medium is part of the organism----in plants, the sap; in animals, the blood. 细胞只能存活在能供养分又能排除废物的液体媒介中。对单细胞生物来说，这就是细胞外的液体，如：大海里、河里或水流中。在对多细胞生物而言，这种媒介就是生物体的一部分，植物以汁液的形式，动物以血液的形式。

The cell membrane is semipermeable, or differentially permeable----some substances can pass through it, but others cannot. This characteristic enables the cell to admit useful substances and to reject harmful substances from the surrounding fluid as well as to force out, or excrete waste products into the fluid. 细胞膜是半渗透性或区别性的渗透膜，即某些物质能渗透。这个特殊性使细胞对细胞周围只吸收了需要的物质而排除掉有害的物质，包括细胞内的废物通过液体化后排出细胞外。

The cell membrane is an extremely thin but tough band of protein and phospholipid molecules. Phospholipids are chemicals similar to stored fat. On the evidence of electron micrographs, biologistsbelieve that it has pores through which certain small molecules pass intact. Substances probably pass through the cell membrane in several ways. Small chambers located on the cell membrane called caveolae gather chemical signals and channel them into the cells. The caveolae may also help distribute proteins throughout the cell. Large molecules enter the cell by a process called diffusion, in which they may be dissolved by substances in the cell membrane. They can then through the membrane without difficulty. Some cells take in large molecules by means of pinocytosis. In this process, the cell membrane forms a pocket around large molecules floating against it. The molecule-and-fluid-filled pocket then breadsloose from the membrane to become a bubblelike vacuole, and the vacuole then drifts into the cytoplasm. Finally, the vacuole wall breaks up and the molecules are released into the cytoplasm. 细胞膜是一种非常薄但确以很坚固的蛋白磷脂膜形成。磷脂是一种类似于储存的脂肪的蛋白物质。通过电子显微镜，生物学家相信细胞膜有孔，使较小的物质完全可以通过。物质可通过多种方式从细胞膜进入。细胞膜上的结构，称“小穴”，可接受化学信号再传到细胞内。小穴还可能参于细胞蛋白的分配。大的分子可通过“渗滤”进入细胞内，或被细胞膜内体分解，使它们更容易的进入细胞内。有些细胞可通过“胞饮”方式吞饮较大的物质。这个过程是通过细胞膜在大物质形成了“带”把它包围着，将它以泡状的“液泡”引入细胞质，最后包围解散，大物质成功的进入细胞内。 The cytoplasm细胞质

The cytoplasm is mainly water. Its water content varies from a minimum of about 65 percent to a

maximum of about 95 percent. The solids in the cytoplasm include granular proteins, carbohydrates, droplets of fat, and pigments. The cytoplasm is thus a colloidal system. 细胞质主要成分是“水”。水分含量有百分之65到最高，百分之95。细胞质内的固体包括蛋白颗粒、碳水化合物、脂肪小滴和色素。细胞质是胶体性的。

The cytoplasm may be either watery or syrupy, depending on the concentration of solids dispersed in the fluid. When the solid content decreases, these structures seem to vanish. Changes in concentration also produce an apparent steaming of the cytoplasm from place to place within the cell. This occurs, for example, when food molecules enter the cell. 细胞质可能是水性或糖浆性，根据散在细胞质内固体的浓度。当固体成分浓度增多，膜状和纤维状结果在细胞质显出。而当固体成分浓度减少时，膜状和纤维状的结构就消失。浓度的变化还可以表现细胞质内局部流动的变化。食物分子进入时可见。

Most of the cell’s constant work of keeping alive is performed in the cytoplasm. Here food molecules are changed into the material needed for energy and materials for growth or stiffening of the cell membrane are manufactures needed by the rest of the organism. For example, plant cells containing chlorophyll manufacture glucose----a plant food----from carbon dioxide and water. 大部分为了细胞存活的工作都在此处（细胞质）完成的。在此处，食物物质将被转化成提供细胞能量的材料和提供细胞生长的材料，或细胞膜的增强剂所生产。多细胞植物的细胞质还是生产了对其他生物提供食物的物质。列如：植物叶绿素所产生的葡萄糖，植物的食物，从水和二氧化碳合成。

One of the cytoplasm’s key energy transactions occurs in the sausage-shaped mitochondria. Each mitochondrion has an inner and an outer membrane. Like the cell membrane, the membranes of the mitochondrion are semipermeable. Food molecules that pass into the cytoplasm are taken into the mitochondria and oxidized, or burned, for energy. 细胞质能量转换的要点发生在锥状形的线粒体。每个线粒体都有内膜和外膜。像细胞膜一样，线粒体的膜也是半渗透性。进入线粒体的食物分子被氧化提供出能量。

The endoplasmic reticulum, a network of membranous tubes, runs through the cytoplasm. In the opinion of some biologists, this network is a continuous structure that begins at the cell membrane, twists through the cytoplasm, and ends at the membrane surrounding the nucleus. Located along the endoplasmic reticulum as well as elsewhere in the cytoplasm are numerous ribosomes. These tiny granules consist in part of ribonucleic acid (RNA). Proteins are manufactured at the ribosomes. The Golgi complex, or Golgi apparatus, is a membranous structure composed of stacks of thin sacs. Newly made proteins move from the endoplasmic reticulum to the Golgi complex, where they are stored for later secretion. 胞浆网，在细胞质中由膜所形成管状的网。有些生物学家认为这是一种连续性结构，始点为细胞膜，在细胞膜内扭绞，终点为细胞核的膜。分布于胞浆网包括细胞质中某处的是核糖体。这些小颗粒是核糖核酸所形成的。蛋白质是在核糖体合成的。高尔基体是膜状囊包堆成层形成的。新合成的蛋白从胞浆网移动到高尔基体储存，为了后来分泌所用。

Vacuoles drift through the cytoplasm and usually carry food molecules in solution. Lysosomes are structures somewhat similar in appearance to vacuoles but denser. They appear to have a digestive function. Each lysosome is filled with digestive enzymes and encased in a membrane. Lysosomes are believed to break down food substances brought into the cell by pinocytosis. It has been suggested that the Golgi complex plays a part in the formation of lysosomes. 在细胞质内游动的液泡一般是带着食物分子的溶液。溶酶体是一种有点像液泡的结构，但较稠。它是用来消化的。每个溶酶体的膜内都是添装着消化酶。我们认为它是消化

通过“胞饮”方式的大物质。也认为高尔基体对溶酶体的形成有关系。

The Nucleus细胞核

Near the center of the cell is a roundish or oval-shaped nucleus. The nucleus controls the growth and division of the cell. It also contains the structures that transmit hereditary traits. 细胞的中央，圆形或椭圆形的就是细胞核。细胞核控制细胞的生长和分化。也装着遗传信息。

Enclosed by a two-layered membrane, the nucleus contains a liquid called nucleoplasm as well as strands of deoxyribonucleic acid (DNA) covered with a coating of protein. A strand of DNA consists of a long series of genes, which are the units of heredity of plants and animals. Genes determine the characteristics of a cell. They do this by regulating the production of RNA, which in turn controls the manufacture of specific proteins. 被两层膜圈住着，细胞核内含有称为“核质（浆）”的液体和脱氧核糖核酸的蛋白层。脱氧核糖核酸缕是很长的基因系列所组成的，它是植物和动物的遗传信息。基因决定了细胞的特征。它是通过调节核糖核酸，使核糖核酸产出特异的蛋白。

Human cells, for example, make only proteins unique to human beings DNA strands are usually too thinly strung out to be seen with an optical microscope. Because the strands are readily stained with dyes, they are called chromatin. When a cell begins to divide, however, the chromatin thickens into the form of chromosomes. 列如：人的细胞，只产出人独特拥有的蛋白。脱氧核糖核酸缕一般都很细小过光学显微镜能观察到。因为脱氧核糖核酸缕能够染色后部分被染，称“染色质”。细胞分化过程中，染色体拾起变厚形成了“染色体”。

A nucleus not undergoing division has at least one nucleolus. The nucleolus contains a concentration of RNA. Biologists think RNA is made initially in the nucleus according to a DNA “blueprint” and stored there until needed for protein manufacture. 细胞核分化核仁不会减少，最少要有一个核仁。核仁含有丰富的核糖核酸。生物学家认为核糖核酸原本在核仁里，根据脱氧核糖核酸的蓝图造出而藏在此处直到有蛋白合成的需要。

the nucleus of animal cells is a spherical structure called the centrosome, from which asters radiate. The centrosome contains a pair of rodded structure called centrioles, which usually lie at right angles to each other. Although centrioles and centrosomes have not been seen in plant cells, biologists believe that plant cells contain similar structures. 靠近动物的细胞核的圆形结构叫“中心体”，可见呈放射状散发的星体。中心体内含有一对棍状结构，称为“中心粒”，一般都形成正确固定的角度。无法在植物细胞发现中心体和中心粒，但生物学家认为植物应该有存在类似功能的其他结构。 Tissues组织

Cells are organized into tissues that perform specific functions. The four basic tissue types are as follows: 多细胞组成了组织，为了特异的功能。四种基本的组织：

Epithelial tissues----covers and protects body structures and lines organs, vessels, and cavities. 上皮组织 : 覆盖及保护着身体结构和分清器官、导管和空腔。

Connective tissues----supports and binds body structures. It contains fibers and other nonliving material between the cells; included are fat tissues, cartilage, bone and blood. 结缔组织: 支柱和联结着身体结构。包括细胞之间的纤维和其它无生物结构。包括脂肪组织、软骨、骨头和血液。

Muscle tissues----contracts to produce movement. The three types are：skeletal or voluntary muscle that moves the skeleton; the cardiac muscle of the heart; and the smooth muscle that forms the walls of the abdominal organs. Cardiac and smooth muscle can function without conscious control and are thus described as involuntary muscle. 肌肉组织: 通过收拾来产生动

作。分为三种：骨骼肌，作用于一般骨骼移动。心机，心脏的肌肉。平滑肌，形成胃肠道壁的肌肉。心机和平滑肌是非意识性，不随意性肌肉。

Nervous tissue——makes up the brain, spinal cord, and nerves. It coordinates and controls body responses by transmitting electrical impulses. 神经组织: 组成大脑、脊椎和神经。它是通过动作电位来超空身体。

The simplest tissues are membranes. Mucous membranes secrete thick fluid called mucus that protects underlying tissues. Serous membranes secrete a thin, watery fluid. They line body cavities and cover organs. 最简单的组织就是膜。粘液膜分泌出粘稠的胶液，起得组织保护作用。粘液组织分泌出较稀的粘液，起得身体导管的分界和覆盖着各个器官。

Human diseases

In this passage you will learn: 1.disease and pathology 2.the classification of diseases 3.germs’ invasion of the human body 4.the body’s defense against invasion 5.the body’s immunity to diseases

The brief survey of the human body in Chapter One has given us a glimpse into two different studies that are considered the fundamentals of medical sciences, namely anatomy and physiology. However, the picture is not complete without considering pathology, the science that deals with the structural and functional changes produced by the disease. In fact, the modern approach to the study of disorder emphasizes the close relationship of the pathological and physiological aspects and the need to understand the fundamentals of each in treating any body diseases. 第一章中，通过对人体的概论，即解剖学与生理学，我们对两种被认为是医学基础的不同学科有了一个大致的印象。然而如果我们不考虑病理学，这门涉及由疾病带来的结构和功能变化的学科，上述的人体概论就不是完整的。实际上，现代对疾病的研究方法强调了病理学与生理学方面的密切关系，强调了我们在治疗任何人体疾病方面需要了解病理学与生理学基础的重要性。

Then what is a disease? It may be defined as a condition that impairs the proper function of the body or of one of its parts. Every living thing, both plants and animals, can succumb to disease. People, for example, are often infected by tiny bacteria, but bacteria, in turn, can be infected by even more minute viruses. 那么什么是疾病呢？它可能被定义为正常的功能或是部分功能遭受损害时的一种状态。每一种生物、植物和动物，都会受制于疾病。例如，人类常常被微小的细菌所感染，但是，反过来说，细菌又能够被甚至更加微小的病毒所感染。

Hundreds of different diseases exist. Each has its own particular set of symptoms and signs, clues that enable a physician to diagnose the problem. A symptom is something a patient can detect, such as fever, bleeding, or pain. A sign is something a doctor can detect, such as a swollen blood vessel or an enlarged internal body organ. 许多种疾病存在于世。每一种都有其特定的症状、征兆和线索，医生能以此诊断疾病之所在。症状是病人自己就能觉察到的，比如，高烧、流血，或是疼痛。而征兆则是医生能够观察到的，比如，血管扩张或是体内器官肿大。

Diseases can be classified differently. For instance, an epidemic disease is one that strikes many persons in a community. When it strikes the same region year after year it is an endemic disease. An acute disease has a quick onset and runs a short course. An acute heart attack, for example, often hits without warning and can be quickly fatal. A chronic disease has a slow onset and runs a sometimes years-long course. The gradual onset and long course of rheumatic fever makes it a chronic ailment. Between the acute and chronic, another type is called subacute. 疾

病可以划分为不同的种类，例如，流行病是一种在某一社区内侵袭许多人的疾病。当它年复一年地袭击同一社区，就成了一种地方病。急性病发作快，但病程短，举个例子来说，急性心脏病发作常常没有前兆，而且会很快致命。慢性病发作则慢，但病程有时会长达几年之久。风湿热正是由于发病慢、病程长而成为一种慢性失调病（慢性病）。而介于急性与慢性之间的另一种类型，就被称为亚急性。

Diseases can also be classified by their causative agents. For instance, an infectious, or communicable, disease is the one that can be passed between persons such as by means of airborne droplets from a cough or sneeze. Tiny organisms such as bacteria and fungi can produce infectious diseases. So can viruses. So can tiny worms. Whatever the causative agent might be, it survives in the person it infects and is passed on to another. Sometimes, a disease-producing organism gets into a person who shows no symptoms of the disease. The asymptomatic carrier can then pass the disease on to someone else without even knowing he has it. 疾病也可以依其病原体来划分，例如，传染病也叫作可传播的疾病，就是一种通过咳嗽和打喷嚏造成的空气小粒来传播的疾病。极小的有机体，如，细菌和真菌可导致传染病。病毒和小虫子也不例外。不论病原体会是什么样，只要它存活于人体内就能够传染给别人。有时，一个致病的有机体侵人人体后，该人却没有显示带病的症状。于是无症状的病原携带者甚至在自己也不知情的情况下就把疾病传染给了他人。

Noninfectious diseases are caused by malfunctions of the body. These include organ or tissue degeneration, erratic cell growth, and faulty blood formation and flow. Also included are disturbances of the stomach and intestine, the endocrine system, and the urinary and reproductive systems. Some diseases can be caused by diet deficiencies, lapses in the body's defense system, or a poorly operating nervous system. 非传染性疾病是由身体功能失调引起的。这包括血管或组织退化、异常细胞生成，以及异常的血液生成和血液循环。当然其中也包括胃、肠、内分泌系统和泌尿生殖系统的紊乱。一些疾病也可能是由饮食不足、身体抵抗力下降、或是神经系统工作不造成的。

Disability and illnesses can also be provoked by psychological and social factors. These ailments include drug addiction, obesity, malnutrition, and pollution-caused health problems. 心理因素和社会因素也会引发残废和疾病，这些病包括吸毒成性、肥胖、营养不良和由污染造成的健康问题。

Furthermore, a thousand or more inheritable birth defects result from alternations in gene patterns. Since tiny genes are responsible for producing the many chemicals needed by the body, missing or improperly operating genes can seriously impair health. Genetic disorders that affect body chemistry are called inborn errors of metabolism. Some forms of mental retardation are hereditary. 而且，有上千种乃至为数更多的遗传性出生缺陷是由于基因变化而造成的。由于小小的基因负责着生产许多身体所需的化学物质，它的遗失或是工作状态不良都会严重损害健康。因基因失调而被影响了的身体化学反应被称之为先天性代谢失调。一些眢力发育迟缓就是因遗传而造成的。

How Germs Invade the Body病菌是怎样侵袭身体

Humans live in a world where many other living things compete for food and places to breed. The pathogenic organisms, or pathogens, often broadly called germs, that cause many diseases are able to invade the human body and use its cells and fluids for their own needs. Ordinarily, the body's defense system can ward off these invaders.人类生活在有一个有许多其它生物竞争食物和求得繁衍的世界里。很多致病的有机体或病原体，通常被我们广义地称为病菌的东西能侵入人体并利用其细胞和组织液来供它们自身的需求。一般来讲，身体防御系统能够阻止这

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