Unit 1

Reading A 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 action s. ‖ 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、功能和作用更能使他满足。‖包括杰佛逊在内的杰出思想家均持有这个观点,但有趣的是,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,态度其实是充满矛盾的。一方面,人们被肉体的奥妙所深深着迷,另一方面,却又对其深感敬畏,这在一定程度上与远古的忌禁遥相呼应,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.

( 研究人体的途径可谓纷繁多样。对愤世嫉俗者来说,人体贱为粘土陋室;对吟诗作赋者来说,人体尊为灵魂的宫殿;对救死扶伤者来说,人体悲为脆弱多病的躯壳。精神病学家视其为思想和性格的居所。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 t he 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.


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.


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.



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.

(为了高效的运转,因而细胞需要得到身体的帮助:食物提供可释放能量的原材料,氧气帮助分解食物,水分转运无机物,比如钠、钾。一旦这些需要得到满足,细胞本身就会提供复杂的机制,使其维持正常运作必须的平衡状况——总之,能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 from the incredibly thin membranes in the lung or kidney that permit the filtering or exchange of dissolved body fuels and wastes.



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.


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.


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 hormones that regulate the body’s chemical reactions.



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.


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.



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 patient’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.