醫(yī)學英語翻譯

1、-作者xxxx-日期xxxx醫(yī)學英語翻譯【精品文檔】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 ha

2、ve held this belief, but curiously, 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

3、 the conviction that the body is too complicated to understand. “在我看來，”托馬斯杰佛遜于1814年寫道：“對人來說，沒有什么知識會比了解自身的架構(gòu)、部件、以及他們的功能和運動更能使他滿足?！痹诮芊疬d前后的杰出思想家均持有這個觀點，但激發(fā)人好奇心的是，這個觀點并不為普羅大眾所由衷地接受。人們對自己的身體（這個對他自身來說最為寶貴的財富）的態(tài)度其實是充滿矛盾的。一方面，人們對身體感到非常著迷，另一方面，卻又對其深感敬畏，這在一定程度上是受古代禁忌的影響，也在一定程度上反映了人們確信肉體過于復雜而難以理解。 The possible

4、 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 ow

5、n kind. The biologist sees it as an organism which can alter the future as a result of the experience of the past. 研究人體的方法可謂紛繁多樣。對憤世嫉俗者來說，人體賤如粘土陋室；對吟詩作賦者來說，人體尊如靈魂的宮殿；對內(nèi)科醫(yī)生來說，人體是脆弱多病的軀殼。精神病學家視其為理智和個性的居所。遺傳學家當其為自我繁衍的機器。生物學家視其為能借過往的經(jīng)驗來改變未來的生命體。 All the specialized scientific views of the body are valid

6、. All, however, must start 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. 所有有關(guān)人體的專

7、業(yè)科學的觀點都是有依據(jù)的，然而，所有的這些都必須有同一個前提：那就是對研究人體的基本結(jié)構(gòu)和功能的解剖學和生理學的認識。我們對身體的了解的基本原則是，所有生物都是由結(jié)構(gòu)和功能基本相似的細胞構(gòu)成的。A Swarm of Tiny Specialists Studies 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

8、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. 關(guān)于細胞的研究細胞是什么，它

9、是干什么的和如何復制的已經(jīng)表明細胞本身就是一個令人難以置信的復雜世界。細胞的一大精妙之處在于其體積之微細與其活性之大之間的反差。每個細胞是如此渺小，以至于在一個半英寸立方體大小的人體組織中可能發(fā)現(xiàn)數(shù)以萬計的細胞。然而，每個細胞都堪比一個繁忙到難以想象的并有著高度的分工的化學實驗室。 The cell has two main parts: a nucleus, containing the genetic material deoxyribonucleic acid (DNA), and a surrounding semifluid cytoplasm. Bounding the cytop

10、lasm is the cell membrane, which 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 contain

11、ing DNA split. It is in the cytoplasm, 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 s

12、ynthesis of proteinalong with reproduction, a major function of most cells. Another packages the manufactured protein for transport wherever needed in the body. 細胞有兩個主要部分：含有遺傳物質(zhì)脫氧核糖核酸（DNA）的細胞核，以及周圍呈半流質(zhì)的細胞質(zhì)。包圍著細胞質(zhì)的是細胞膜，它包含著細胞內(nèi)容物,并將不需要的物質(zhì)隔離在外，然而它允許營養(yǎng)物質(zhì)和代謝廢物通過。細胞核細胞的控制中心調(diào)控細胞質(zhì)的主要活動；然而，它最美妙的時刻是當細胞分裂時，包含D

13、NA的染色體分裂繁殖。細胞日復一日的工作是在細胞質(zhì)中完成的。各種組件或細胞器，都是一個個卓越的技術(shù)專家。其中一個功能是分解從細胞膜進入細胞的營養(yǎng)物質(zhì)，并將其轉(zhuǎn)化成能量。另一個功能是提供蛋白質(zhì)合成的場所伴隨著細胞復制的全過程，這是大多數(shù)細胞的主要功能。再一個功能是加工包裝制造的蛋白質(zhì) ，并將其運輸?shù)缴眢w所需的各個部位。 To operate efficiently, the cell thus requires specific help from the body as a whole: food to provide raw material for the release of energ

14、y, 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 kilterin short, to keep the body alive and healthy. 為了工作的高效運行，細胞需

15、要得到身體的特定的幫助，總的來說：食物提供可釋放能量的原材料，氧氣幫助分解食物，水用于運輸無機物，比如鈣、鈉。一旦這些需要得到滿足，細胞自身就會通過錯綜復雜的機制，來保持正常運作所必須的平衡確使身體處于正常狀態(tài)簡而言之，就是保持身體的活力和健康。 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

16、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 bodys usethe hormones produced in the endocrine glands, or the digestive enzymes poured into the intesti

17、ne 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.細胞擁有一定的共性，但是大部分的人體細胞具有他們特化的特征和功能。那些構(gòu)成骨的細胞能沉積鈣鹽，這些細胞連鎖成堅固而無活動能力的塊狀固體。相比之下，血液中那些可以抵抗細菌侵略的白細胞，卻能在身體內(nèi)自由流動。某些細胞能產(chǎn)生特殊的化學物質(zhì)供身體使用如內(nèi)分泌腺產(chǎn)生的激

18、素，由胰腺分泌并進入腸道的消化酶。還有些細胞在肺或腎臟形成非常薄的膜，使其能夠過濾或交換已被溶解的身體燃料和廢物。 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

19、 together by reason of underlying similarities. 根據(jù)它們各自的特點和所要求的功能，細胞形成不同種類的組織：骨、肌肉、血液、神經(jīng)、結(jié)締組織和上皮組織。構(gòu)成這些組織的細胞是不同的，但因潛在的相似之處而同屬一類。 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

20、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 t

21、he 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，腸道的肌纖維比腿部細長的肌纖維更圓、更短，但是當這兩種細胞

22、都受到化學或電刺激時，它們都會發(fā)生強有力地收縮。構(gòu)成骨組織的細胞是有相當程度的不同，它們可以在一處形成脆骨，而在另一處形成疏松而有彈性的軟骨；然而，所有的細胞能儲存鈣鹽，使骨成為鈣化的結(jié)構(gòu)。支撐皮下脂肪的疏散網(wǎng)狀細胞和維持膝關(guān)節(jié)在恰當位置的密集膠囊狀細胞，都共同參與構(gòu)成了結(jié)締組織。盡管可能有所不同，所有的神經(jīng)細胞都能接受并傳導電化學沖動；盡管可能有所不同，所有的血細胞都能在循環(huán)流體血漿中自由地漂浮。 The most versatile cells are those of the various kinds of epithelium. Forming the bodys external

23、coatingthe skinepithelial 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 tr

24、ansparent 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 bodys chemical reactions. 最萬能的細胞是各種各樣的上皮細胞。它們共同構(gòu)成人體的外套皮膚

25、，上皮細胞保護皮膚里面的物質(zhì)不受外界侵害。它們還構(gòu)成口腔、胃黏膜、腸黏膜、血管內(nèi)皮和參與肺呼吸以及腎排泄的膜。 覆布于眼角膜上的上皮細胞，它們變成一種透明的擋風玻璃，使得光束自由地進入到視網(wǎng)膜。其他的上皮細胞分泌保護性的粘液保持腸、肺和鼻腔不至于變干燥。還有一些上皮細胞能夠產(chǎn)生高效能的激素來調(diào)節(jié)人體化學反應(yīng)。Interlock and Overlap The tissues comprise the structural materials of the bodys organ systems. These, in turn, may be compared to a number of co

26、rporations with interlocking directorates. 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, endocri

27、ne, 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 urogenitalunder the resounding

28、 title of splanchnological system. 人體器官系統(tǒng)的物質(zhì)結(jié)構(gòu)由組織組成。換言之，這就像互相之間交叉任職的董事的若干公司。事實上這些相互依賴的器官系統(tǒng)在他們數(shù)量多少的問題上也曾引發(fā)了一些爭論。備受推崇的Gray解剖學-曾被被醫(yī)學生使用了上百年的時間-列舉出了十個系統(tǒng)：神經(jīng)系統(tǒng)，消化系統(tǒng)，呼吸系統(tǒng)，血管系統(tǒng)，泌尿生殖系統(tǒng)，內(nèi)分泌系統(tǒng)，骨骼系統(tǒng)，肌肉系統(tǒng)，關(guān)節(jié)和皮膚系統(tǒng)。而另一些權(quán)威人士則因關(guān)節(jié)和骨頭是密不可分的而將他們歸為一類，或是將感覺器官從神經(jīng)系統(tǒng)分離出來，或是將所有的內(nèi)臟器官-呼吸器官，消化器官，內(nèi)分泌器官以及泌尿器官混在一塊，冠以內(nèi)臟系統(tǒng)這一聲勢浩大的名稱。

29、 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 on

30、e point or another. The wonder is that breakdowns are the exception rather than the rule. 然而比給他們的命名更為重要的是他們各個系統(tǒng)之間會相互影響這個事實，其中一個系統(tǒng)的衰弱可以損害或毀滅其他系統(tǒng)。當然，理想狀態(tài)下，所有的系統(tǒng)都是能一直完美地執(zhí)行他們的任務(wù)的。而不幸的是，自然狀態(tài)下是不可能出現(xiàn)這么完美的情況的。在所有系統(tǒng)當中，他們總會因這個方面或那個方面的故障而受到損害。神奇的是，出現(xiàn)故障倒是例外而不是常規(guī)情況 Within the healthy body itself there is no abso

31、lute 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

32、varies. One of the practitioners major 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

33、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.在健康的人體內(nèi)對于“正?！币矝]有確切的標準可言。變化不僅僅發(fā)生在個體之間，也可以發(fā)生在個體內(nèi)部，有時候每個小時都不同，這要看他們當時的運動狀態(tài)。醫(yī)生私下開玩笑說，即使是一個狒狒，它也可以在醫(yī)學院校畢業(yè)，前提是他學會很深沉地說“因人而異”。令從醫(yī)者最頭痛的問題之一就是要確認一個人的情況是真正生

34、病了還是處于正常的變化范圍之中。有些范圍內(nèi)的波動可能是已經(jīng)被一些統(tǒng)計資料所確認的。健康的心臟重量范圍是240360g，健康的肝臟重量在10002000g之間，血糖濃度水平是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 throug

35、h 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 comp

36、licated” machine” is called anatomy.人體是一個非常復雜并且高效的機器。它通過呼吸系統(tǒng)吸入并且吸收氧氣。然后這富含氧的血液通過心血管系統(tǒng)被分布到所有的組織。消化系統(tǒng)將能消化的食物轉(zhuǎn)變成能量并且將剩余的廢物排出。骨骼-肌系統(tǒng)組成了人體的輪廓。全身最大的器官皮膚,幾乎覆蓋整個軀體。這門研究機體復雜構(gòu)造的科學被稱為“解剖學” One of the major systems is the skeletal-muscular system. The body is supported and given shape by this structure, consist

37、ing 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. 主要的系統(tǒng)之一是骨骼-肌系統(tǒng)。人體由這個結(jié)構(gòu)作支撐并構(gòu)成形態(tài)，這一結(jié)構(gòu)由200多塊骨和肌肉及與之相連的肌腱組成。它們很堅固但是能夠通過彎曲關(guān)節(jié)。它們也能像防護物一樣，保護內(nèi)部重要的器官

38、免受傷害。 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 b

39、ody 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. 人體的骨骼像鋼鐵一樣堅韌但是骨骼更輕更柔韌。這些骨骼由礦物質(zhì)，有機物，水構(gòu)成-它們通過一種被稱為膠原的類似結(jié)合劑的物質(zhì)連結(jié)起來，并且充滿了紅骨髓和黃骨髓。紅骨髓產(chǎn)生一種能夠運輸氧氣到達全身各處的血紅細胞，然而黃骨髓由脂肪細胞組成

40、。有一種堅韌的膜被稱為骨膜，它覆蓋了大部分骨的表面，使骨頭能得到血液的滋養(yǎng)。 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

41、 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

42、 to the pelvis. Bones are united by joints and held together by ligaments. 身體中一個主要的骨骼結(jié)構(gòu)是脊柱。它貫穿人體背部并且保護脊髓，有很多重要的神經(jīng)位于這里。脊柱是由屬于結(jié)締組織的韌帶連接起來的椎骨組成的，并且相鄰椎骨由椎間盤分隔開。在脊柱的頂部是顱骨，顱骨包裹并且保護腦。在頸部以下連著脊柱的是12對肋骨，共同構(gòu)成了胸廓。脊柱的底部是骶骨，骶骨把脊柱和骨盆連接在一起。骨骼通過關(guān)節(jié)聯(lián)合并且通過韌帶連結(jié)。 Muscles are special fibrous tissues found throughout the b

43、ody. 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

44、heart, are involuntary and are operated automatically by the central nervous system.肌肉是遍布身體的特殊纖維組織。它們通過收縮來回應(yīng)神經(jīng)信號從而控制運動和許多器官功能. 骨骼肌能被意識控制，所以稱為隨意肌。它們通過一個叫肌腱的結(jié)實纖維組織緊緊附著于骨上。其他肌肉，例如胃肌和心肌，都是非隨意肌，由中樞神經(jīng)系統(tǒng)控制，自動運作. The most important muscles in the body is the heart. Without the heart and its cardiovascular (

45、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. 心肌是人體最

46、重要的肌肉，沒有心肌和它的心血管循環(huán)系統(tǒng)，人類將不可能生存。心臟大概兩個拳頭那么大，平均每分鐘收縮72次或接近38000000次每年。這種有節(jié)奏的收縮稱之為脈搏, 并且可以在手腕的橈動脈處感覺到。 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 sy

47、stole, 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 durin

48、g 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.人的心臟由四個腔室組成, 兩個心房和兩個心室, 每個腔都是由許多層心肌環(huán)繞，盤旋排列而成。（心臟）在收縮階段，被稱為收縮期，富含氧的血液從左心室泵出進入主動脈，然后從那里通過動脈運送到全身

49、所有的器官。二氧化碳是這個過程中產(chǎn)生的廢物，通過血液收集。血液在心臟舒張期通過靜脈和腔靜脈回流到右心房。從那，血液被泵入右心室并通過肺動脈被送到肺部，在那二氧化碳被移除，氧氣被加入。 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 b

50、ody!這個（心臟）系統(tǒng)的其余部分則是由小動脈，小靜脈及最微小的血管毛細血管構(gòu)成，總的來說，人體中的血管長度遠遠超過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 ,

51、which controls the rate at which energy is produced（the metabolic rate）.心血管系統(tǒng)也參與運輸一些由內(nèi)分泌系統(tǒng)的腺體分泌且直接進入血漿的激素。這些激素控制身體的許多功能。例如，甲狀腺分泌甲狀腺素，這種激素控制著能量產(chǎn)生的速度（代謝率）。 The respiratory system starts at the nasal passage, where air is breathed in during inspiration. There the air is filtered and its temperature reg

52、ulated. 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 redistribut

53、ed along the circulatory system. The entire process is called respiration and occurs at the rate of about 16 to 20 times per minute. 呼吸系統(tǒng)始于鼻腔通道，即吸氣時空氣進入的地方。在那里（鼻腔）空氣被過濾，溫度被調(diào)節(jié)。然后，空氣通過喉和氣管進入支氣管和細支氣管，最后進入肺部被稱作肺泡的小氣泡里面。被用過的血液清除二氧化碳并通過呼氣過程排出。凈化后的血液隨后被氧化并且隨著循環(huán)系統(tǒng)被重新分配。這整個過程稱為呼吸，它發(fā)生的頻率在每分鐘16到20次之間。 The larg

54、est 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 u

55、p 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

56、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 type

57、s of glands-sweat glands and oil glands. The innermost subcutis contains fat cells, blood vessels, and nerves. 人體最大的器官就是包裹在人體表層的皮膚（一般人的皮膚面積平均約為20平方英尺）。皮膚加上與之相關(guān)的結(jié)構(gòu)（頭發(fā)，指甲，皮脂腺和汗腺，以及專門能使身體感受觸摸，冷，熱，痛苦和壓力的感受器）共同組成了皮膚系統(tǒng)。皮膚能保護機體免受微生物和其他雜質(zhì)的傷害，防止體液流失，及調(diào)節(jié)體溫。 三層組織組成皮膚-表皮，真皮，和皮下組織(皮下層)。表皮是在不斷增長的，在表皮下層新形成的細胞會不斷地替

58、代外層死亡的細胞。頭發(fā)，指甲和腳趾甲都是表皮的特化形式。在表皮中也發(fā)現(xiàn)了被稱為黑色素的著色色素。中間層（或真皮層）是皮膚的兩種主要腺體，汗腺和皮脂腺的所在地。 最里面的皮下組織包含脂肪細胞，血管和神經(jīng)。 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 foods carbohydrates. This taking of food into the body for digestion is called ingestion. 另一個主要的身體復合體是消化系統(tǒng)，該系統(tǒng)對食物進行加工處理，以便食物能被作為能量使用。該過程開始于口腔，食物被牙齒嚼碎和粉碎。在口腔里，由唾液腺分泌的唾液提供的酶