藥學(xué)英語第五版原文翻譯

1、精選優(yōu)質(zhì)文檔-傾情為你奉上Introduction to PhysiologyIntroduction Physiology is the study of the functions of living matter. It is concerned with how an organism performs its varied activities: how it feeds, how it moves, how it adapts to changing circumstances, how it spawns new generations. The subject is vast

2、and embraces the whole of life. The success of physiology in explaining how organisms perform their daily tasks is based on the notion that they are intricate and exquisite machines whose operation is governed by the laws of physics and chemistry.Although some processes are similar across the whole

3、spectrum of biologythe replication of the genetic code for or examplemany are specific to particular groups of organisms. For this reason it is necessary to divide the subject into various parts such as bacterial physiology, plant physiology, and animal physiology.To study how an animal works it is

4、first necessary to know how it is built. A full appreciation of the physiology of an organism must therefore be based on a sound knowledge of its anatomy. Experiments can then be carried out to establish how particular parts perform their functions. Although there have been many important physiologi

5、cal investigations on human volunteers, the need for precise control over the experimental conditions has meant that much of our present physiological knowledge has been derived from studies on other animals such as frogs, rabbits, cats, and dogs. When it is clear that a specific physiological proce

6、ss has a common basis in a wide variety of animal species, it is reasonable to assume that the same principles will apply to humans. The knowledge gained from this approach has given us a great insight into human physiology and endowed us with a solid foundation for the effective treatment of many d

7、iseases.The building blocks of the body are the cells, which are grouped together to form tissues. The principal types of tissue are epithelial, connective, nervous, and muscular, each with its own characteristics. Many connective tissues have relatively few cells but have an extensive extracellular

8、 matrix. In contrast, smooth muscle consists of densely packed layers of muscle cells linked together via specific cell junctions. Organs such as the brain, the heart, the lungs, the intestines, and the liver are formed by the aggregation of different kinds of tissues. The organs are themselves part

9、s of distinct physiological systems. The heart and blood vessels form the cardiovascular system; the lungs, trachea, and bronchi together with the chest wall and diaphragm form the respiratory system; the skeleton and skeletal muscles form the musculoskeletal system; the brain, spinal cord, autonomi

10、c nerves and ganglia, and peripheral somatic nerves form the nervous system, and so on.Cells differ widely in form and function but they all have certain common characteristics. Firstly, they are bounded by a limiting membrane, the plasma membrane. Secondly, they have the ability to break down large

11、 molecules to smaller ones to liberate energy for their activities. Thirdly, at some point in their life history, they possess a nucleus which contains genetic information in the form of deoxyribonucleic acid (DNA).Living cells continually transform materials. They break down glucose and fats to pro

12、vide energy for other activities such as motility and the synthesis of proteins for growth and repair. These chemical changes are collectively called metabolism. The breakdown of large molecules to smaller ones is called catabolism and the synthesis of large molecules from smaller ones anabolism. In

13、 the course of evolution, cells began to differentiate to serve different functions. Some developed the ability to contract (muscle cells), others to conduct electrical signals (nerve cells). A further group developed the ability to secrete different substances such as hormones or enzymes. During em

14、bryological development, this process of differentiation is re-enacted as many different types of cell are formed from the fertilized egg. Most tissues contain a mixture of cell types. For example, blood consists of red cells, white cells, and platelets. Red cells transport oxygen around the body. T

15、he white cells play an important role in defense against infection and the platelets are vital components in the process of blood clotting. There are a number of different types of connective tissue but all are characterized by having cells distributed within an extensive noncellular matrix. Nerve t

16、issue contains nerve cells and glial cells.The Principal Organ SystemsThe cardiovascular systemThe cells of large multicellular animals cannot derive the oxygen and nutrients they need directly from the external environment. The oxygen and nutrients must be transported to the cells. This is one of t

17、he principal functions of the blood, which circulates within blood vessels by virtue of the pumping action of the heart. The heart, blood vessels, and associated tissues form the cardiovascular system.The heart consists of four chambers, two atria and two ventricles, which form a pair of pumps arran

18、ged side by side. The right ventricle pumps deoxygenated blood to the lungs where it absorbs oxygen from the air, while the left ventricle pumps oxygenated blood returning from the lungs to the rest of body to supply the tissues. Physiologists are concerned with establishing the factors responsible

19、for the heartbeat, how the heart pumps the blood around the circulation, and how it is distributed to perfuse the tissues according to their needs. Fluid exchanged between the blood plasma and the tissues passes into the lymphatic system, which eventually drains back into the blood.The respiratory s

20、ystemThe energy required for performing the various activities of the body is ultimately derived from respiration. This process involves the oxidation of foodstuffs to release the energy they contain. The oxygen needed for this process is absorbed from the air in the lungs and carried to the tissues

21、 by the blood. The carbon dioxide produced by the respiratory activity of the tissues is carried to the lungs by the blood in the pulmonary artery where it is excreted in the expired air. The basic questions to be answered include the following: How is the air moved in and out of the lungs? How is t

22、he volume of air breathed adjusted to meet the requirements of the body? What limits the rate of oxygen uptake in the lungs?The digestive systemThe nutrients needed by the body are derived from the diet. Food is taken in by the mouth and broken down into its component parts by enzymes in the gastroi

23、ntestinal tract. The digestive products are then absorbed into the blood across the wall of the intestine and pass to the liver via the portal vein. The liver makes nutrients available to the tissues both for their growth and repair and for the production of energy. In the case of the digestive syst

24、em, key physiological questions are: How is food ingested? How is it broken down and digested? How are the individual nutrients absorbed? How is the food moved through the gut? How are the indigestible remains eliminated from the body?The kidneys and urinary tractThe chief function of the kidneys is

25、 to control the composition of the extracellular fluid. In the course of this process, they also eliminate non-volatile waste products from the blood. To perform these functions, the kidneys produce urine of variable composition which is temporarily stored in the bladder before voiding. The key phys

26、iological questions in this case are: how do the kidneys regulate the composition of the blood? How do they eliminate toxic waste? How do they respond to stresses such as dehydration? What mechanisms allow the storage and elimination of the urine? The reproductive systemReproduction is one of the fu

27、ndamental characteristics of living organisms. The gonads produce specialized sex cells known as gametes. At the core of sexual reproduction is the creation and fusion of the male and female gametes, the sperm and ova (eggs), with the result that the genetic characteristics of two separate individua

28、ls are mixed to produce offspring that differ genetically from their parents.The musculoskeletal systemThis consists of the bones of the skeleton, skeletal muscles, joints, and their associated tissues. Its primary function is to provide a means of movement, which is required for locomotion, for the

29、 maintenance of posture, and for breathing. It also provides physical support for the internal organs. Here the mechanism of muscle contraction is a central issue. The endocrine and nervous systems.The endocrine and nervous systemsThe activities of the different organ systems need to be coordinated

30、and regulated so that they act together to meet the needs of the body. Two coordinating systems have evolved: the nervous system and the endocrine system. The nervous system uses electrical signals to transmit information very rapidly to specific cells. Thus the nerves pass electrical signals to the

31、 skeletal muscles to control their contraction. The endocrine system secretes chemical agents, hormones, which travel in the bloodstream to the cells upon which they exert a regulatory effect. Hormones play a major role in the regulation of many different organs and are particularly important in the

32、 regulation of the menstrual cycle and other aspects of reproduction.The immune system provides the bodys defenses against infection both by killing invading organisms and by eliminating diseased or damaged cells.Although it is helpful to study how each organ performs its functions, it is essential

33、to recognize that the activity of the body as a whole is dependent on the intricate interactions between the various organ systems. If one part fails, the consequences are found in other organ systems throughout the whole body. For example, if the kidneys begin to fail, the regulation of the interna

34、l environment is impaired which in turn leads to disorders of function elsewhere.HomeostasisComplex mechanisms are at work to regulate the composition of the extracellular fluid and individual cells have their own mechanisms for regulating their internal composition. The regulatory mechanisms stabil

35、ize the internal environment despite variations in both the external world and the activity of the animal. The process of stabilization of the internal environment is called homeostasis and is essential if the cells of the body are to function normally.Taking one example, the beating of the heart de

36、pends on the rhythmical contractions of cardiac muscle cells. This activity depends on electrical signals which, in turn, depend on the concentration of sodium and potassium ions in the extracellular and intracellular fluids. If there is an excess of potassium in the extracellular fluid, the cardiac

37、 muscle cells become too excitable and may contract at inappropriate times rather than in a coordinated manner. Consequently, the concentration of potassium in the extracellular fluid must be kept within a narrow range if the heart is to beat normally.How Does The Body Regulate Its Own Composition?T

38、he concept of balanceIn the course of a day, an adult consumes approximately 1 kg of food and drinks 23 liters of fluid. In a month, this is equivalent to around 30 kg of food and 6090 liters of fluid. Yet, in general, body weight remains remarkably constant. Such individuals are said to be in balan

39、ce; the intake of food and drink matches the amounts used to generate energy for normal bodily activities plus the losses in urine and feces. In some circumstances, such as starvation, intake does not match the needs of the body and muscle tissue is broken down to provide glucose for the generation

40、of energy. Here, the intake of protein is less than the rate of breakdown and the individual is said to have a negative nitrogen balance. Equally, if the body tissues are being built up, as is the case for growing children, pregnant women and athletes in the early stages of training, the daily intak

41、e of protein is greater than the normal body turnover and the individual is in positive nitrogen balance.This concept of balance can be applied to any of the body constituents including water and salt and is important in considering how the body regulates its own composition. Intake must match requi

42、rements and any excess must be excreted for balance to be maintained. Additionally, for each chemical constituent of the body there is a desirable concentration range, which the control mechanisms are adapted to maintain. For example, the concentration of glucose in the plasma is about 45mmol/L betw

43、een meals. Shortly after a meal, plasma glucose rises above this level and this stimulates the secretion of the hormone insulin by the pancreas, which acts to bring the concentration down. As the concentration of glucose falls, so does the secretion of insulin. In each case, the changes in the circu

44、lating level of insulin act to maintain the plasma glucose at an appropriate level. This type of regulation is known as negative feedback. During the period of insulin secretion, the glucose is being stored as either glycogen or fat.A negative feedback loop is a control system that acts to maintain

45、the level of some variable within a given range following a disturbance. Although the example given above refers to plasma glucose, the basic principle can be applied to other physiological variables such as body temperature, blood pressure, and the osmolality of the plasma. A negative feedback loop

46、 requires a sensor of some kind that responds to the variable in question but not to other physiological variables. Thus an osmoreceptor should respond to changes in osmolality of the body fluids but not to changes in body temperature or blood pressure. the information from the sensor must be compar

47、ed in some way with the desired level by some form of comparator. if the two do not match ,an error signal is transmitted to an effector, a system that can act to restore the variable to its desired level .these features of negative feedback can be appreciated by examining a simple heating system .t

48、he controlled variable is room temperature, which is sensed by a thermostat. the effector is a heater of some kind .when the room temperature falls below the set point, the temperature difference is detected by the thermostat which switches on the heater .this heats the room until the temperature re

49、aches the per set level whereupon the heater is switched off.To summarize, the body is actually a social order of about 100 trillion cells organized into different functional structures, some of which are called organs. each functional structures its share to the maintenance of homeostatic condition

50、s in the extracellular fluid, which is called the internal environment.as long as normal conditions are maintained in this internal environment ,the cells of the body continue to live and function properly. Each cell benefits from homeostasis, and in turn, each cell contributes its share toward the

51、maintenance of homeostasis. This reciprocal interplay provides continuous automaticity of the body until one or more functional systems lose their ability to contribute their share of function. When this happens, all the cells of the body suffer. Extreme dysfunction leads to death; moderate dysfunct

52、ion leads to sickness. 生理學(xué)簡介介紹生理學(xué)是研究生物體功能的科學(xué)。它研究生物體如何進行各種活動，如何飲食，如何運動，如何適應(yīng)不斷改變的環(huán)境，如何繁殖后代。這門學(xué)科包羅萬象，涵蓋了生物體整個生命過程。生理學(xué)成功地解釋了生物體如何進行日?；顒樱诘挠^點是生物體好比是結(jié)構(gòu)復(fù)雜而靈巧的機器，其操作受物理和化學(xué)規(guī)律控制。盡管從生物學(xué)整個范疇看，生物體某些活動過程是相似的如基因編碼的復(fù)制但許多過程還是某些生物體群組特有的。鑒于此有必要將這門學(xué)科分成不同部分研究，如細菌生理學(xué)、植物生理學(xué)和動物生理學(xué)。要研究一種動物如何活動，首先需要了解它的構(gòu)成。要充分了解一個生物體的生理學(xué)活動就必

53、須掌握全面的解剖學(xué)知識。一個生物體的各部分起著什么作用可通過實驗觀察得知。盡管我們對志愿者進行了許多重要的生理調(diào)查，但是實驗條件需要精確控制，所以我們當(dāng)前大多生理知識還是源于對其它動物如青蛙，兔子，貓和狗等的研究。當(dāng)我們明確大多數(shù)動物物種的特定生理過程存在共同之處時，相同的生理原理適用于人類也是合理的。通過這種方法，我們獲得了大量的知識，從而讓我們對人類生理學(xué)有了更深入的了解，為我們有效治療許多疾病提供了一個堅實的基礎(chǔ)。機體的基本組成物質(zhì)是細胞，細胞結(jié)合在一起形成組織。組織的基本類型有上皮組織，結(jié)締組織，神經(jīng)組織和肌組織，每類組織都有各自的特征。許多結(jié)締組織中細胞量相對較少，但是有大量的細胞外

54、基質(zhì)。相比而言，光滑的肌組織由大量密密麻麻的肌細胞通過特定的細胞連接組成。各種器官如腦，心臟，肺，小腸和肝等由不同種類的組織聚集而成。這些器官是不同生理系統(tǒng)的組成部分。心臟和血管組成心血管系統(tǒng)；肺，器官，支氣管，胸壁和膈肌組成呼吸系統(tǒng)；骨骼和骨骼肌組成骨骼肌系統(tǒng)；大腦，脊髓，自主神經(jīng)和神經(jīng)中樞以及周圍軀體神經(jīng)組成神經(jīng)系統(tǒng)等等。細胞在形體和功能上差異很大，但是它們有某些共同的特征。第一，它們由限制膜包被，即細胞質(zhì)膜；第二，細胞有把大分子分解為小分子來釋放活動所需能量的能力；第三，在生命過程中某個階段，細胞體內(nèi)存在一個以脫氧核糖核酸(DNA)形式包含基因信息的細胞核?；铙w細胞不斷轉(zhuǎn)化物質(zhì)。它們?yōu)槠?/p>

55、它活動提供能量分解葡萄糖和脂肪，比如自身生長和修復(fù)所需的蛋白質(zhì)運動和合成。這些化學(xué)變化統(tǒng)稱為新陳代謝。把大分子分解為小分子的過程稱為分解代謝，小分子合成大分子的過程稱為合成代謝。細胞在進化過程中不斷分化進行不同的功能活動。有些細胞具有收縮能力（如肌細胞），有些可以傳導(dǎo)電信號（如神經(jīng)細胞）。進一步進化的細胞能夠分泌不同物質(zhì)如荷爾蒙（如內(nèi)分泌細胞）或酶。胚胎發(fā)育過程中，分化的過程由于很多不同細胞來源于受精卵而再次發(fā)生。大多數(shù)組織包含有不同的細胞類型。比如，血液中含紅細胞，白細胞和血小板。紅細胞運輸全身的氧氣。白細胞在抵御感染時起重要作用，血小板是血液凝集過程中重要的成分。結(jié)締組織有多種不同類型，但

56、有一個共同特征，即細胞分布在豐富的細胞外基質(zhì)中。神經(jīng)組織含神經(jīng)細胞和神經(jīng)膠質(zhì)細胞。主要的器官系統(tǒng)心血管系統(tǒng)大型多細胞動物體的細胞不能從外界環(huán)境中獲取直接所需的氧氣和營養(yǎng)物質(zhì)。這些氧氣和營養(yǎng)物質(zhì)必須轉(zhuǎn)運到細胞。這是血液的主要功能之一，血液憑借心臟的泵血作用在血管內(nèi)流動循環(huán)。心臟、血管和結(jié)締組織組成了心血管系統(tǒng)。心臟包括四個腔，兩個心房和兩個心室構(gòu)成了一對并排存在的泵。右心室將脫氧的血液泵至肺中，肺中的血液吸收空氣中的氧氣，而左心室把從肺回流來的有氧血液泵出至身體其它部位，供應(yīng)給各組織。生理學(xué)家研究促使心臟跳動的因素，心臟如何泵送血液使其循環(huán)，心臟如何根據(jù)各組織所需分配血液。血漿和組織間的流動液體

57、交換流入淋巴系統(tǒng)，最終回流到血液中。呼吸系統(tǒng)機體進行各項活動所需的能量最終來源于呼吸。這一過程包括食物（主要是糖類和脂肪）的氧化，釋放它們所含的能量。這一過程中，氧氣來自于肺中的空氣，經(jīng)由血液到達全身各組織。組織呼吸活動中釋放的二氧化碳由肺動脈中的血液運送至肺，然后呼氣排出體外。需回答的基本問題如下：空氣是如何進出肺的？呼吸的空氣量如何適應(yīng)機體所需？限制肺吸收氧氣頻率的因素是什么？消化系統(tǒng)機體所需營養(yǎng)物質(zhì)來源于飲食。食物經(jīng)口腔進入體內(nèi)，在胃腸道內(nèi)經(jīng)酶將其分解成小分子物質(zhì)。這些消化物通過腸壁吸收入血液，通過門靜脈進入肝臟。經(jīng)肝臟作用后，這些營養(yǎng)物質(zhì)能夠滿足組織生長修復(fù)及能量需求。在消化系統(tǒng)部分，

58、重要的生理學(xué)問題是：食物是如何消化的？食物如何被個體分解消化？個體營養(yǎng)物質(zhì)如何吸收？食物如何在腸內(nèi)轉(zhuǎn)運的？未消化的殘留如何從體內(nèi)排出？泌尿系統(tǒng)腎臟主要功能是控制細胞外液體的形成。在這一過程中，腎臟也會把不可揮發(fā)的廢物排出去。為行使這一功能，在排出之前，腎臟產(chǎn)生含有各種成分的尿液并將其暫時儲存在膀胱中。這一部分主要的生理學(xué)問題是：腎臟如何調(diào)節(jié)血液中的成分？如何排出有毒廢物？如何應(yīng)對像脫水這樣的應(yīng)激反應(yīng)？以及尿液可以存儲和排出體外的機制是什么？生殖系統(tǒng)生殖是活生物體的一個基本特征。生殖腺產(chǎn)生專門的性細胞，被稱為配子。性生殖的核心是雌雄配子即精子和卵子的產(chǎn)生和融合，因此兩個獨立個體的基因特征融合而產(chǎn)

59、生一個基因上與雙親不同的后代。 運動系統(tǒng)這一系統(tǒng)由骨、骨骼肌、關(guān)節(jié)和它們的相關(guān)組織組成。其主要功能是提供運動需要，維持姿勢及呼吸運動。它也為內(nèi)臟器官提供物理支持。這一部分，肌肉收縮機制是主要問題。內(nèi)分泌系統(tǒng)和神經(jīng)系統(tǒng)不同器官系統(tǒng)的活動需要協(xié)作和調(diào)節(jié)，以便共同作用滿足機體需要。人體有兩大調(diào)節(jié)系統(tǒng)：神經(jīng)系統(tǒng)和內(nèi)分泌系統(tǒng)。神經(jīng)系統(tǒng)通過電信號迅速將信息傳導(dǎo)給特定細胞。這樣神經(jīng)將電信號傳遞給骨骼肌以控制收縮。內(nèi)分泌系統(tǒng)分泌化學(xué)物質(zhì)激素。激素通過血流到達施與調(diào)節(jié)作用的細胞。激素在許多不同器官中起著重要作用，在月經(jīng)期調(diào)節(jié)和其它生殖方面尤其重要。免疫系統(tǒng)通過殺死入侵的有機體，清除致病或損傷細胞為機體提供防御功能。雖然研究各器官如何行使功能很有益處，但我們必須認識到機體作為一個整體所做的活動依賴于各器官系統(tǒng)間錯綜復(fù)雜的相互作用。如果一部分無法正常工作，全身其它器官系統(tǒng)也會受到影響。例如，如果腎臟出現(xiàn)問題，內(nèi)部環(huán)境的調(diào)節(jié)受損，結(jié)果導(dǎo)致其它器官系統(tǒng)功能紊亂。穩(wěn)態(tài)各種復(fù)雜機制共同作用調(diào)節(jié)細胞外液的形成，不同個體細胞有自身機制調(diào)節(jié)內(nèi)在組成成分。