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Introduction to Physiology


Introduction



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


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


生理学简介



介绍



生理学是研究生物体功能的科学 。


它研


究生物体如何进行各种活动,如何饮食,如


何运动,如何适应不断改变的环境,如何繁


殖后代。这门学科包罗万象,涵盖 了生物体


整个生命过程。


生理学成功地解释了生物体

< p>
如何进行日常活动,


基于的观点是生物体好


比是结 构复杂而灵巧的机器,


其操作受物理


chemistry.


Although


some


processes


are


similar


across


the


whole


spectrum


of


biology



the


replication


of


the


genetic


code


for


or


example



many


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 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 physiological 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


process


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 diseases.


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


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


parts


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, autonomic 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 molecules to smaller ones to liberate energy for their activities.


和化学规律控制。



尽管从生物学整个 范畴看,


生物体某些


活动过程是相似的


——


如基因编码的复制


——


但许多过程 还是某些生物体群组特有


的。


鉴于此有必要将这门学科分成不同 部分


研究,如细菌生理学、植物生理学和动物生


理学。



要研究一种动物如何活动,


首先需要了


解它的构成。


要充分了解一个生物体的生理


学 活动就必须掌握全面的解剖学知识。


一个


生物体的各部分起着什 么作用可通过实验


观察得知。


尽管我们对志愿者进行了许多重< /p>


要的生理调查,但是实验条件需要精确控


制,

所以我们当前大多生理知识还是源于对


其它动物如青蛙,兔子,猫和狗等的研究。< /p>


当我们明确大多数动物物种的特定生理过


程存在共同之处时,


相同的生理原理适用于


人类也是合理的。通过这种方法,我们获得< /p>


了大量的知识,


从而让我们对人类生理学有


了更深入的了解,


为我们有效治疗许多疾病


提供了一个坚实的 基础。



机体的基本组成物质是细胞,


细胞结合


在一起形成组织。


组织的基本类型有上皮组

< p>
织,结缔组织,神经组织和肌组织,每类组


织都有各自的特征。

< p>
许多结缔组织中细胞量


相对较少,但是有大量的细胞外基质。相比


而言,


光滑的肌组织由大量密密麻麻的肌细


胞通 过特定的细胞连接组成。各种器官如


脑,心脏,肺,小肠和肝等由不同种类的组


织聚集而成。


这些器官是不同生理系统的组


成部 分。心脏和血管组成心血管系统;肺,


器官,支气管,胸壁和膈肌组成呼吸系统;


骨骼和骨骼肌组成骨骼肌系统;


大脑,


脊髓,


自主神经和神经中枢以及周围躯体神经组


成神经系统等等。



细胞在形体和功能上差异很大,


但是它< /p>


们有某些共同的特征。第一,它们由限制膜


包被,即细胞质膜;第 二,细胞有把大分子


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 provide 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


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


embryological


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. The 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 tissue contains nerve cells and glial cells.


The Principal Organ Systems


The cardiovascular system


The 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 the 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


arranged


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


for


the


heartbeat,


howthe


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 system


分解为小分子来释放活动所需能量的能力;


第三,在生命过程中 某个阶段,细胞体内存


在一个以脱氧核糖核酸


(DNA)


形式包含基


因信息的细胞核。



活体细胞不断转化物质。


它们为其它活


动提供能量分 解葡萄糖和脂肪,


比如自身生


长和修复所需的蛋白质运动和合成 。


这些化


学变化统称为新陈代谢。


把大 分子分解为小


分子的过程称为分解代谢,


小分子合成大分


子的过程称为合成代谢。



细胞在进化过程中 不断分化进行不同


的功能活动。有些细胞具有收缩能力(如肌


细 胞)



有些可以传导电信号


(如神经细 胞)



进一步进化的细胞能够分泌不同物质如荷


尔蒙(如内分泌细胞)或酶。胚胎发育过程


中,


分化的 过程由于很多不同细胞来源于受


精卵而再次发生。


< p>
大多数组织包含有不同的细胞类型。



如,血液中 含红细胞,白细胞和血小板。红


细胞运输全身的氧气。


白细胞在 抵御感染时


起重要作用,


血小板是血液凝集过程中重要


的成分。结缔组织有多种不同类型,但有一


个共同特征,


即细胞分布在丰富的细胞外基


质中。神经组织含神经细胞和神经胶质细


胞。



主要的器官系统



心血管系统



大型多细胞动物体的细胞 不能从外界


环境中获取直接所需的氧气和营养物质。



些氧气和营养物质必须转运到细胞。


这是血


液的 主要功能之一,


血液凭借心脏的泵血作


用在血管内流动循环。心 脏、血管和结缔组


织组成了心血管系统。


心脏包括四个腔,


两个心房和两个心室


构成了一对并排存在 的泵。


右心室将脱氧的


血液泵至肺中,


肺中的血液吸收空气中的氧


气,


而左心室把从肺回流来的有氧血 液泵出


至身体其它部位,供应给各组织。生理学家


研究促使心脏 跳动的因素,


心脏如何泵送血


液使其循环,

心脏如何根据各组织所需分配


血液。


血浆和组织间的流动液 体交换流入淋


巴系统,最终回流到血液中。



The energy required for performing the various activities of the body


呼吸系统



is ultimately derived from respiration. This process involves the oxidation


of


foodstuffs


to


release


the


energy


they


contain.


The


oxygen


needed


for


机体进行各项活动所需的能量最终来


this process is absorbed from the air in the lungs and carried to the tissues


源于呼吸。这一过程包括食物(主要是糖类


by the blood. The carbon dioxide produced by the respiratory activity of


和脂肪)的氧化,释放它们所含的能量。这


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


the


volume


of


air


breathed


adjusted


to


meet


the


requirements


of


the


body? What limits the rate of oxygen uptake in the lungs?


The digestive system


The 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


gastrointestinal


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


一过程中,氧气来自于肺中的空气,经由血


液 到达全身各组织。


组织呼吸活动中释放的


二氧化碳由肺动脉中的 血液运送至肺,


然后


呼气排出体外。需回答的基本问题如下:空


气是如何进出肺的?呼吸的空气量如何适


应机体所需?限制肺吸 收氧气频率的因素


是什么?



消化系统



机体所需营养物质来源于饮 食。


食物经


口腔进入体内,


在胃肠道内 经酶将其分解成


小分子物质。


这些消化物通过肠壁吸收入血


both for their growth and repair and for the production of energy. In the


case of the digestive system, 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 tract


The chief function of the kidneys is 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


physiological


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 system


Reproduction


is


one


of


the


fundamental


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


individuals


are


mixed


to


produce


offspring that differ genetically from their parents.


The musculoskeletal system


This


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


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 systems


The activities of the different organ systems need to be coordinated


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


液,通过门静 脉进入肝脏。经肝脏作用后,


这些营养物质能够满足组织生长修复及能

< br>量需求。在消化系统部分,重要的生理学问


题是:


食物是 如何消化的?食物如何被个体


分解消化?个体营养物质如何吸收?食物

< br>如何在肠内转运的?未消化的残留如何从


体内排出?



泌尿系统



肾脏主要功能是控制细胞外 液体的形


成。在这一过程中,肾脏也会把不可挥发的


废物排出去 。


为行使这一功能,


在排出之前,


肾脏 产生含有各种成分的尿液并将其暂时


储存在膀胱中。


这一部分主 要的生理学问题


是:


肾脏如何调节血液中的成分?如何排出


有毒废物?如何应对像脱水这样的应激反


应?以及尿液可以存储和排 出体外的机制


是什么?



生殖系统



生殖是活生物体的一个基本 特征。


生殖


腺产生专门的性细胞,被称为配子。性生殖


的核心是雌雄配子即精子和卵子的产生和


融合,


因此两个独立个体的基因特征融合而


产生一个基因上与双亲不同的后代。



运动系统



这一系统由骨、 骨骼肌、关节和它们的


相关组织组成。其主要功能是提供运动需


要,维持姿势及呼吸运动。它也为内脏器官


提供物理支持。这一部分,肌肉收缩机制是< /p>


主要问题。



内分泌系统和神经系统



不同器官系统 的活动需要协作和调节,


以便共同作用满足机体需要。


人体有两 大调


节系统:神经系统和内分泌系统。神经系统


system. The nervous system uses electrical signals to transmit information


very rapidly to specific cells. Thus the nerves pass electrical signals to the


skeletal muscles to control their 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 regulation of the menstrual cycle and other aspects of reproduction.


The


immune


system


provides


the


body’s


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


to


recognize


that


the


activity


of


the


body


as


a


whole


is


通过电信号迅速将信息传导给特定细胞。



样神经将 电信号传递给骨骼肌以控制收缩。


内分泌系统分泌化学物质


―< /p>


激素。


激素通过


血流到达施与调节作用的 细胞。


激素在许多


不同器官中起着重要作用,

< br>在月经期调节和


其它生殖方面尤其重要。



免疫系统通过杀死入侵的有机体,


清除


致病或损伤细 胞为机体提供防御功能。



虽然研究各器官如何行使功能很有益


处,


但我们必须认识到机体作为一个整体所

做的活动依赖于各器官系统间错综复杂的


相互作用。如果一部分无法正常工作,全身


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 internal environment is impaired which in turn leads to


disorders of function elsewhere.


Homeostasis


Complex 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 stabilize


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


depends


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 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?


The concept of balance


In the course of a day, an adult consumes approximately 1 kg of food


and drinks 2~3 liters of fluid. In a month, this is equivalent to around 30


kg of food and 60~90 liters of fluid. Yet, in general, body weight remains


remarkably constant. Such individuals are said to be in balance; 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 andmuscle


tissue


is


broken


down


to


provide


glucose


for


the


generation


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


其它器官系统也会受到影响。例如,如果肾


脏出现问题,内部环境的调节受损,结果导< /p>


致其它器官系统功能紊乱。



稳态



各种复杂机制共同作用调节细胞 外液


的形成,


不同个体细胞有自身机制调节内在


组成成分。


尽管外界环境和动物活动不停变


化,调节机 制维持着体内环境的稳定。内部


环境的稳定被称为稳态,


它是机 体能够正常


发挥作用所必须的。



例如 ,


心脏的跳动依赖于心肌细胞有节


律的收缩。这一活动依赖于电 信号,而电信


号反过来依赖存在于细胞外和细胞内液体


中钠和钾 离子的浓度。


如果细胞外液中钾离


子过多,心肌细胞兴奋性增强 ,可能出现不


规律的收缩。因此,要维持心脏正常跳动,


细胞外 液中钾离子的浓度就必须控制在一


定范围内。



机体如何调节物质成分



平衡的概念



一天中,


一个成人需要消耗约


1


千克食


物,


2~3


升液体。以一个月计算,这相当于

< br>约


30


千克食物,


60~90< /p>


升液体。


然而,


一般

来说,机体体重是基本不变的。这类个体可


以说处于平衡状态。

食物和液体的摄入量相


当于正常机体活动消耗的能量加上尿液和

粪便中丢失的能量。在一些情况下,如饥饿


状态,摄入量与机体所需量并不相当,肌 组


织断裂,提供葡萄糖产生能量。蛋白质的摄


入低于肌组织断裂 的速度,


机体处于负氮平


衡。同样地,如果机体组织正处于生长 期,


如生长期的儿童,


孕妇和早期训练阶段的运


动员,


那么蛋白质的日常摄入量比正常机体


所需要的多 。


相反,


此时个体处于


正氮

< p>
平衡。



tissues


are


being


built


up,


as


is


the


case


for


growing


children,


pregnant


women


and


athletes


in


the


early


stages


of


training,


the


daily


intake


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 requirements


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


example, the concentration of glucose in the plasma is about


4~5mmol/L


between


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


circulating


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 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 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


compared


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


.the


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 reaches 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


conditions


in


the


extracellular


fluid,


which


is


called


the


internal 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


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


平衡的概念可以应用到机体的任何构


成成分上,包括水和盐,而且平衡在机体调


节其自身成分上是非常重要的 。


摄入必须等


于所需,为维持机体平衡,任何多余的能量


都必须排出。此外,因为机体的每种化学成


分都有一个可取的浓度范围 ,


控制机制维持


这个范围。例如,两餐间血糖浓度大约为


4~5mmol/L


。进食后不久,血糖含量超过这

< br>一范围,刺激胰腺分泌胰岛素,降低浓度。


随着葡萄糖浓度的下降,胰岛素分泌减 少。


在此情况下,


循环胰岛素水平的改变都是为


了使血浆中的葡萄糖维持在一个合适的范


围内。这种调节称为负反馈机制。在胰 岛素


分泌期间,


葡萄糖像肝糖原或脂肪一样被储


存。



负反馈调节是在机体出现紊乱时,


将一


些变量控制在限定范围内的一个控制系统。


虽然 上面的例子讲到血糖,


但这一基本原则


可以应用到其它生理变量 中如体温、


血压和


血浆的渗透浓度。


负 反馈调节需要一种能对


不确定的变量做出反应而对其它生理变量


不应答的传感器。因此,渗透压感受器应该


能对机体体液渗透的变化而不是体温和血


压的变化产生应答。


感受器传递的信息必须


和理想水平(系统的调定点)以比较者的身


份,


以某种方式进行 比较。


如果两者不相符,


一个错误信号就会传递给效应器,


效应器是


一种能使变量保持在理想水平的系统。

负反


馈的这些特点可以通过检测一种简单的加


热系统来理解 。被控制的变量是室温,它可


以由一个温度计检测到,


效应器是 一种加热


器。当室温降低到调定点以下时,温度计就


可以监测到 温度的变化而开启加热器,


对室


内进行加温,

< br>直到室温升高到先前调好的调


定点,加热器关闭。



总而言之,


机体实际上是由


100


万亿细


胞有序组成了不同的功能结构,


其中一些 被


称为器官。


每个功能结构都在维持细胞外液

< br>稳态方面发挥其作用,这称之为内环境。只


要内部环境处于正常状态,

< p>
机体细胞继续生


存并正常运行。每个细胞都从稳态中获益,


反过来,每个细胞都为稳态做出贡献。这种


相互作用促使机体持续自主运行,< /p>


直至一个


或多个功能系统不能正常运转。此时,机体


所有细胞都会受损。


功能极度异常会导致死


亡,轻微 的功能异常导致疾病的发生。



dysfunction leads to death; moderate dysfunction leads to sickness.





The Other Side of Antibiotics


Antibiotics


have


eliminated


or


controlled


so


many


infectious


diseases that virtually everyone has benefited from their use at one time


or another. Even without such personal experience, however, one would


have


to


be


isolated


indeed


to


be unaware


of


the


virtues,


real


and


speculative,


of


these


“miracle”


drugs.


The


Am


erican


press,


radio,


and


television have done a good job of reporting the truly remarkable story


of


successes


in


the


chemical


war


on


germs.


What’s


more,


any shortcomings on their part have been more than made up for by the


aggressive


public


relations


activity


of


the


pharmaceutical companies


抗生素的另一面



抗生素已经消除或控 制了很多传染


病,实际上每个人都从这种或那种使用中


受益。即 使没有这样的个人经验,人们也


不得不孤立地认识到这些



奇迹



药物的优


点 ,真实性和推测性。美国新闻界,广播


电台和电视台在报道有关细菌化学战争成


功的真实故事方面做得很好。更重要的是,


制造和销售抗生素的制药公司 的积极的公


共关系活动已经弥补了他们的缺点。



which manufacture and sell antibiotics.


In


comparison,


the


inadequacies


and


potential


dangers


of


these


remarkable


drugs


are


much


less


widely


known.


And


the


lack of


such


knowledge


can


be


bad,


especially


if


it


leads


patients


to


pressure


their


doctors


into


prescribing


antibiotics


when


such


medication


isn’t


really


needed, or leads them to switch doctors until they find one who is, so to


speak, antibiotics-minded.


Because


the


good


side


of


the


antibiotics


story


is


so


very


well-known,


there


seems


more


point


here


to


a


review


of


some


of the


immediate and long-


range problems that can come from today’s casual


use


of


these


drugs.


It


should


be


made


clear


in advance


that


calamities


from the use of antibiotics are rare in relation to the enormous amounts


of the drugs administered. But the potential hazards, so little touched on


generally,


do


need


a


clear


statement.


The


antibiotics


are


not,


strictly speaking, exclusively prescription drugs. A number of them are


permitted


in


such


over-the-counter


products


as


nasal


sprays, lozenges,


troches, creams, and ointments. Even if these products do no harm, there


is


no


point


whatsoever


in


using


them.


If you


have


an


infection


serious


enough


to


warrant


the


launching


of


chemical


warfare,


you


need


much


bigger doses of the antibiotics than any of the non-prescription products


are allowed to contain.


Over-the-counter


products,


however,


account


for


only


a


small


percentage of total antibiotics production. It is


the prescription dosages


that


give


people


trouble.


These


drugs



even


allowing


for


the


diverse


abilities


of


the


many narrow-spectrum


ones


and


the


versatility


of


the


broad- spectrum


ones



are


not


the


cure- alls,


they


often


are


billed


as


being. There are wide gaps in their ability to master contagious diseases.


Such important infections as mumps, measles, common colds, influenza,


and infectious hepatitis still await conquest. All are virus infections and


despite


intense


efforts,


very


little progress


has


been


made


in


chemotherapy


against


viruses.


Only


small


progress


has


been


achieved


against fungi. Many strains


of bacteria and fungi are naturally resistant


to


all


currently


available


antibiotics


and


other


chemotherapeutic


drugs.


Some microorganisms


originally


sensitive


to


the


action


of


antibiotics,


especially


staphylococcus,


have


developed


resistant


strains.


This


acquired resistance imposes on the long range value of the drugs a very


important


limitation,


which


is


not


adequately met


by


the


frequent


introduction of new antimicrobial agents to combat the problem.


相比之下,这些显着 的药物的不足之


处和潜在的危险是广为人知的。缺乏这样


的知识 可能是不好的,特别是如果它导致


病人迫使他们的医生处方抗生素,当这种


药物是不是真的需要,或导致他们切换到


医生,直到他们找到一个谁可以说, 抗生




-


头脑。



因为抗生素故事的好处是如此 众所周


知,在这里似乎更重要的是要回顾一下当


今随便使用这些 药物可能产生的一些近期


和远期问题。应该预先说明,使用抗生素


造成的灾难与所投入的大量药物有关。但


是一般来说很少涉及的潜在危害确实需要


一个明确的说法。严格来说,抗生素不是


完全处方药。它们中的一些 允许用于鼻腔


喷雾剂,锭剂,锭剂,霜剂和软膏等非处


方产品。 即使这些产品没有坏处,使用它


们也没有任何意义。如果感染的严重程度


足以保证发动化学战争,则需要比任何非


处方产品所含的抗生素剂量大得多的抗 生


素。



然而,非处方药产品仅占抗生 素总产


量的很小比例。这是给人们麻烦的处方剂


量。这些药物, 即使考虑到许多窄谱药物


的多样性和广谱药物的多样性,也不是治


愈所有的药物,


他们往往被称为



药 物





握传 染病的能力差距很大。像腮腺炎,麻


疹,感冒,流行性感冒和传染性肝炎等重

< p>
要感染仍在等待征服。所有这些都是病毒


感染,尽管付出了巨大的努力,但 在化学


疗法方面进展甚微。真菌只取得小的进展。


许多细菌和真 菌菌株对所有目前可用的抗


生素和其他化学治疗药物都具有天然的抗

性。一些原本对抗生素作用敏感的微生物,


特别是葡萄球菌,已经产生了耐药菌株。


这种获得的耐药性对药物的远距离价值提


出了一个非常重要的限 制,而这种限制并


不能通过频繁引入新的抗菌剂来解决这个


It


has


been


pretty


well


established


that


the


increase


in


strains


of


bacteria resistant to an antibiotic correlates directly with the duration and


extent


of


use


of


that


antibiotic


in


a


given


location.


In


one


hospital


a


survey showed that, before erythromycin had been widely used there, all


strains of staphylococci taken from patients and personnel were sensitive


to


its


action.


When


the


hospital


started


extensive


use


of


erythromycin,


however, resistant staphylococcus strains began to appear.


The


development


of


bacterial


resistance


can


be


minimized


by


a


more


discriminating


use


of


antibiotics,


and


the


person taking


the


drug


can help here. When an antibiotic must be used, the best way to prevent


the development of resistance is to wipe out the infection as rapidly and


thoroughly as possible.


Ideally, this


requires a bactericidal drug, which


问题。



已经确定的是,对抗生素耐药的细菌


菌株的增加直接与在给定位 置使用抗生素


的持续时间和程度相关。在一家医院进行


的一项调 查显示,在红霉素被广泛使用之


前,所有从患者和人员中获得的葡萄球菌


菌株对其作用敏感。当医院开始广泛使用


红霉素时,耐药葡萄球菌菌株开始出现 。



细菌耐药性的发展可以通过更加区分


使用抗生素来最小化,服用这种药物的人


可以在这里帮助。当必须使用抗生素时,


防止抗药性发展的最好方法是尽可能迅速


destroys, rather than a bacteriostatic drug, which inhibits. And the drug


must


be


taken


in


adequate


dosage


for


as


long


as


it


is necessary


to


eradicate


the


infection


completely.


The


doctor,


of


course,


must


choose


the


drug,


but


patients


can


help


by


being sure


to


take


the


full


course


of


treatment recommended by


the doctor, even though symptoms seem to


disappear before all the pills are gone. In rare instances the emergence of


resistance


can


be


delayed


or


reduced


by


combinations


of


antibiotics.


Treatment


of


tuberculosis


with


streptomycin


alone


results


in


a


high


degree of resistance, but if para-aminosalicylic acid or isoniazid is used


with


streptomycin


the


possibility


that


this


complication


will


arise


is


greatly reduced.


In


hospital


treatment


of


severe


infections,


the


sensitivity


of


the


infecting


organism


to


appropriate


antibiotics


is determined


in


the


laboratory before treatment


is started. This enables the


doctor to select


the most effective drug or drugs; it determines whether the antibiotic is


bactericidal


or


bacteriostatic


for


the


germs


at


hand; and


it


suggests


the


amount needed to destroy the growth of the bacteria completely. In either


hospital or home, aseptic measures can help to reduce the prevalence of


resistant strains of germs by preventing cross infection and the resultant


spreading of organisms.


Every


one


of


the


antibiotics


is


potentially


dangerous


for


some


people.


Several


serious


reactions


may


result


from


their use.


One


is


a


severe,


sometimes


fatal,


shock-like


anaphylactic


action,


which


may


strike


people


who


have


become


sensitized


to penicillin.


Anaphylactic


reaction happens less frequently and is less severe when the antibiotic is


given


by


mouth.


It


is most


apt


to


occur


in


people


with


a


history


of


allergy,


or


a


record


of


sensitivity


to


penicillin.


Very


small


amounts


of penicillin, even the traces which get into the milk of cows for a few


days


after


they


are


treated


with


the


antibiotic


for mastitis,


may


be


sufficient


to


sensitize;


hence,


the


strong


campaign


by


food


and


drug


officials keeps such milk off the market.


To


minimize


the


risk


of


anaphylactic


shock


in


illnesses


where


injections of penicillin are the preferred treatment, a careful doctor will


question the patient carefully about allergies and previous reactions. In


case


of


doubt


another antibiotic


will


be


substituted


if


feasible,


or


other


precautionary measures will be taken before the injection is given.


Other


untoward


reactions


to


antibiotics


are


gastrointestinal


彻底地消灭感染。理想情 况下,这需要一


种杀菌药物,而不是一种抑制抑制药物的


杀菌药 物。只要有必要彻底根除感染,必


须服用足够的药物。当然,医生必须选择


药物,但即使在所有药丸消失之前症状似


乎消失,患者仍然可以通过确保服用 医生


推荐的整个治疗过程来提供帮助。在极少


数情况下,抵抗的 出现可以通过抗生素的


组合来延迟或减少。单独使用链霉素治疗


结核病会导致高度的耐药性,但是如果对


氨基水杨酸或异烟肼与链霉素一起使用,


则会出现这种并发症的可能性大大降低。



在 医院治疗严重感染时,在开始治疗


之前,在实验室中确定感染生物对适当抗


生素的敏感性。这使医生能够选择最有效


的药物或药物


;


它决定了抗生素是否对手边


的细菌具有杀菌或抑菌作用


;


它提示了完全


消灭细菌生长所需的量。在 医院或家中,


无菌措施可以通过预防交叉感染和生物体


的扩散来 帮助减少耐药菌株的流行。



每一种抗生素都对某些人有潜在危


险。他们的使用可能会导致一些严重的反


应。一种是严重的,有 时是致命的,类似


休克的过敏反应,可能会引起对青霉素敏


感的 人。口服抗生素时,过敏反应发生频


率较低,严重程度较轻。最容易发生在有

< p>
过敏史或对青霉素有敏感记录的人群中。


非常少量的青霉素,甚至在用抗生 素治疗


乳腺炎之后进入母牛乳中几天的痕迹可能


足以致敏。因此 ,食品和药物官员的强力


运动使这种牛奶不在市场上。



为了尽量减少注射青霉素是首选治疗


的疾病过敏性休克的风险,谨慎的 医生会


仔细询问病人有关过敏和以前的反应。如


果有疑问,如果 可行,另一种抗生素将被


替代,或在注射前采取其他预防措施。



对抗生素的其他不良反应是使用四环


disorders



such


as


sore


mouth,


cramps,


diarrhea,


or


anal itch



which


occur most frequently after


use of the tetracycline group but have also


been


encountered


after


use


of


penicillin and


streptomycin.


These


reactions


may


result


from


suppression


by


the


antibiotic


of


bacteria


normally


found


in


the gastrointestinal


tract.


With


their


competition


removed,


antibiotic- resistant


staphylococci


or


fungi,


which


are


also


normally present,


are


free


to


flourish


and


cause


what


is


called


a


super- infection. Such infections can be extremely difficult to cure.


A


few


antibiotics


have


such


toxic


effects


that


their


usefulness


is


strictly


limited.


They


include


streptomycin


and dihydrostreptomycin,


which


sometimes


cause


deafness,


and


chloramphenicol,


which


may


injure


the


bone


marrow.


Drugs


with


such serious


potential


dangers


as


素组后最频繁出现的胃肠疾病



-


例如口


疮,痉挛,腹泻或肛门瘙痒 ,但在使用青


霉素和链霉素后也遇到过。这些反应可能


是由抗生 素抑制胃肠道中正常发现的细菌


引起的。通过消除竞争,抗生素抗性葡萄


球菌或真菌(通常也存在)可以自由繁殖


并引起所谓的超感染。这种感染可能极 难


治愈。



一些抗生素有这样的毒性作 用,它们


的用途是严格限制的。它们包括有时引起


耳聋的链霉素 和二氢链霉素,以及可能伤


害骨髓的氯霉素。只有在生命受到威胁的

these should be used only if life is threatened and nothing else will work.


All the possible troubles that can result from antibiotic treatment should


not


keep


anyone


from


using


one


of


these


drugs


when


it


is


clearly indicated. Nor should they discourage certain preventive uses of


antibiotics which have proved extremely valuable.





情况下才能使用这类具有如此严重潜在危


险的药物,否则就不能起作用 。在抗生素


治疗中可能产生的所有可能的麻烦都不应


该使任何人 在使用这些药物时明确指出。


他们也不应该阻止某些已被证明非常有价

< br>值的抗生素的预防性用途。



Discovery of Insulin, and the Making of a


Medical Miracle


Background


Insulin


is


a


hormone


that


regulates


the


amount


of


glucose


(sugar) in the blood and is required for the body to function normally.


Insulin is produced by β


-cells in the pancreas, also called the islets of


Langerhans.


These


cells


continuously


release


a


small


amount


of


insulin into the body, but release surges of the hormone in response to


胰岛素的发现和医学奇迹的建立



背景



胰岛素是一种调节血液中葡萄糖


(糖)



量的激素,

< br>是人体正常功能所必需的。


胰岛素


由胰腺中的

< p>
β


细胞产生,也称为朗格罕氏胰


岛。这些细胞不断 释放少量的胰岛素进入人


体,但随着血糖水平的升高而释放激素的激

增。



体内的某些细胞会将摄入的食物转化为


a rise in the blood glucose level.


Certain cells in the body change the food ingested into energy,


or


blood


glucose,


that


cells


can


use.


Every


time


a


person


eats,


the


blood


glucose


rises.


Raised


blood


glucose


triggers


the


cells


in


the


islets


of


Langerhans


to


release


the


necessary


amount


of


insulin.


Insulin allows the blood glucose to be transported from the blood into


the cells. Cells have an outer wall, called a membrane, which controls


what enters and exits the cell. Researchers do not yet know exactly


how insulin works, but they do know insulin binds to receptors on the


cell


membrane.


This


activates


a


set


of


transport


molecules


so


that


glucose


and


proteins


can


enter


the


cell.


The


cells


can


then


use


the


glucose as energy to carry out its functions. Once transported into the


cell, the blood glucose level is returned to normal within hours.


Without insulin, the blood glucose builds up in the blood and the


cells are starved of their energy source. Some of the symptoms that


may


occur


include


fatigue,


constant


infections,


blurred


eye


sight,


numbness, tingling in the hands or legs, increased thirst, and slowed


healing of bruises or cuts. The cells will begin to use fat, the energy


source stored for emergencies. When this lasts for too long a time the


body produces ketones, chemicals produced by the liver. Ketones can


poison


and


kill


cells


if


they


build


up


in


the


body


over


an


extended


period of time. This can lead to serious illness and coma.


People


who


do


not


produce


the


necessary


amount


of


insulin


have


diabetes.


There


are


two


general


types


of


diabetes.


The


most


severe


type,


known


as


Type


or


juvenile-onset


diabetes,


is


when


the


body


does


not


produce


any


insulin,


Type


I


diabetics


usually


inject


themselves


with


different


types


of


insulin


three


to


four


times


daily.


Dosage is taken based on the person's blood glucose reading, taken


from a glucose meter. Type n diabetics produce some insulin, but it is


either


not


enough


or


their


cells


do


not


respond


normally


to


insulin.


This usually occurs in obese or middle aged and older people. Type II


diabetics do not necessarily need to take insulin, but they may inject


insulin once or twice a day.


How Insulin Almost Wasn't Discovered


Before


the


discovery


of


insulin,


diabetes


was


a


feared


disease


that


most


certainly


led


to


death.


Patients


wasted


away,


grew


weak,


and


suffered


indescribably


before


their


inevitable


death.


They


had


细胞可以利用的能 量或血糖。


每人一吃,


血糖


就会升高。


升高的血糖引发朗格汉斯胰岛中的


细胞释放必要量的胰岛素。< /p>


胰岛素允许血液从


血液运输到细胞。细胞有一个外壁,称为膜,< /p>


它控制着什么进入和离开细胞。


研究人员尚不

清楚胰岛素是如何工作的,


但他们知道胰岛素


与细胞膜上的 受体结合。


这激活了一组转运分


子,


使 葡萄糖和蛋白质可以进入细胞。


然后细


胞可以使用葡萄糖作为能 量来执行其功能。



旦运送到细胞中,


血糖水平在数小时内恢复正


常。



如果 没有胰岛素,


血液中的血糖会积聚在


血液中,

< br>细胞就会缺乏能量来源。


可能发生的


一些症状包括疲劳, 感染持续,视力模糊,手


脚麻木,


手脚刺痛,

< br>口渴增加,


伤口愈合减慢。


细胞将开始使用脂肪,紧急情 况下储存的能


源。当这种持续时间太长时,身体会产生酮,


肝脏 产生的化学物质。


如果酮在体内长时间累


积,

< br>酮可以毒杀细胞。


这可能导致严重的疾病


和昏迷。



不产生必需量的胰岛素的人患有糖尿病。


有 两种一般类型的糖尿病。


最严重的类型,


类型或青少年型糖尿病,


是当身体不产生任何


胰岛素时,< /p>


I


型糖尿病患者通常每天注射不同


类型的 胰岛素三至四次。


根据从葡萄糖计取得


的人的血糖读数来服用剂 量。



n


型糖尿病患者


会产生一些胰岛素,


但这或者是不够的,


或者


他们的细胞对胰岛素没有正常的反应。


这通常


发 生在肥胖或中年人和老年人。



II


型 糖尿病


患者不一定需要服用胰岛素,


但可以每天注射

< p>
一次或两次胰岛素。



胰岛素几乎没有被发现



在发现胰岛素 之前,


糖尿病是一种可怕的


疾病,最可能导致死亡。病人浪费了 ,变得虚


弱,


在不可避免的死亡之前难以形容。


他们渴


望饥渴,


但饥饿只是让事情变得更糟,


继续减


肥。医生知道,糖会加重糖尿病患者的病情,

最有效的治疗方法是将病人的糖摄入量控制


insatiable


thirst


and


hunger,


but


trying


to


satisfy


their


hunger


only


made things worse, and they continued to lose weight. Doctors knew


that


sugar


worsened


the


condition


of


diabetic


patients


and


that


the


most


effective


treatment


was


to


put


the


patients


on


very


strict


diets


where


sugar


intake


was


kept


to


a


minimum.


At


best,


this


treatment


could buy patients a few extra years, but it never saved them. In some


cases, the harsh diets even caused patients to die of starvation.


During the nineteenth century, observations of patients who died


of diabetes often showed that the pancreas was damaged. In 1869, a


German


medical


student,


Paul


Langerhans,


found


that


within


the


pancreatic tissue that produces digestive juices there were clusters of


cells


whose


function


was


unknown.


Some


of


these


cells


were


eventually


shown


to


be


the


insulin-producing


beta


cells.


Later,


in


honor


of


the


person


who


discovered


them,


the


cell


clusters


were


named the islets of Langerhans.


In


1889


in


Germany,


physiologist


Oskar


Minkowski


and


physician


Joseph


von


Mering,


showed


that


if


the


pancreas


was


removed from a dog, the animal got diabetes. But if the duct through


which


the


pancreatic


juices


flow


to


the


intestine


was


ligated-surgically tied off so the juices couldn't reach the intestine-the


dog


developed


minor


digestive


problems


but


no


diabetes.


So


it


seemed that the pancreas must have at least two functions:



?



To produce digestive juices


?



To produce a substance that regulates the sugar glucose.



This hypothetical internal secretion was the key.


If a substance


could actually be isolated, the mystery of diabetes would be solved.


Progress, however, was slow.


In


1920,


an


unknown


Canadian


surgeon


named


Frederick


Banting


approached


Professor


John


Macleod,


the


head


of


the


University


of


Toronto's


physiology


department,


with


an


idea


about


finding


that


secret. He


theorized


that


the pancreatic digestive


juices


could


be


harmful


to


the


secretion


of


the


Pancreas


produced


by


the


islets


of


Langerhans.


He


therefore


wanted


to


ligate


the


pancreatic


ducts in order to stop the flow of nourishment to the pancreas. This


would cause the pancreas to degenerate, making it shrink and lose its


ability to secrete the digestive juices. The cells thought to produce an


antidiabetic


secretion


could


then


be


extracted


from


the


pancreas


without


being


harmed.


Unfortunately,


Macleod,


a


leading


figure


in


the


study


of


diabetes


in


Canada,


didn't


think


much


of


Banting's


theories and rebuffed his suggestion. Despite this, Banting managed


to


convince


Macleod


that


his


idea


was


worth


trying.


Macleod


gave


Banting


a


laboratory


with


a


minimum


of


equipment


and


ten


dogs.


Banting


also


got


an


assistant,


a


medical


student


by


the


name


of


Charles Best. The experiment was set to start in the summer of 1921.


Banting


and


Best


began


their


experiments


by


removing


the


pancreas from a dog. This resulted in the following:



?



It's blood sugar rose.


?



It became thirsty drank lots of water, and urinated more often.


?



It


became


weaker


and


weaker


Experimenting


on


another


dog, < /p>


在非常严格的水平。


充其量,


这种治疗可 以多


买几年的病人,


但从来没有挽救过。


在某些情


况下,严酷的饮食甚至导致病人死于饥饿。



在十九世纪期间,


死于糖尿病的病人的观


察结 果常常表明胰脏已经受损。



1869


年,一


位德国医学学生


Paul Langerhans


发现,


在产生


消化液的胰腺组织内,有功能未 知的细胞簇。


其中一些细胞最终被证明是产生胰岛素的


β


细胞。后来,为了纪念发现他们的人,细胞群


被命名为朗格汉斯岛。< /p>



1889


年在德国,生理学家奥斯卡< /p>


·


闵可夫


斯基(


Oskar Minkowski


)和医师约瑟夫


·

< p>


·



林(


Joseph von Mering


)发现,如果将胰脏从


狗身上取下,动物就会患上糖尿病。但是,如


果将胰液流入肠道的导管结扎在外 科手术中,


使得汁液不能到达肠道,


那么狗就会产生轻微


的消化问题,


但不会产生糖尿病。


所以胰腺似


乎至少有两个功能:



?



产生消化液



?



生产调节糖分的物质。



这个假设的内 分泌是关键。


如果一个物质


实际上可以孤立,

< br>糖尿病的奥秘将被解决。



进展缓慢。

< br>


1920












·




(< /p>


Frederick Banting



的未知加拿大外科医生向


多伦多大学生理学系主任约翰


·


麦克劳德



John


Macleod


)教授提供了一个关于如何找到这个


秘密的想 法。


他推论胰腺消化液可能对朗格汉


斯胰岛产生的胰腺分泌有害 。


因此,


他想结扎


胰管,


以阻止营养物流向胰腺。


这会导致胰腺


退化,使其萎 缩,失去分泌消化液的能力。认


为产生抗糖尿病分泌物的细胞然后可以从胰


腺中提取而不受伤害。


不幸的是,


加拿大糖尿


病研究领域的领军人物麦克劳德(


Macleod


对班廷的理论并没有太多的想法,


并且拒绝了

< p>
他的建议。


尽管如此,


万津设法说服了麦克劳


德,


他的想法值得尝试。


麦克劳德给班廷一 个


实验室,


配备了最少的设备和十只狗。


班廷还


找到了一位名叫查尔斯


·


贝斯 特的医学助理。


实验定于


1921


年夏 天开始。



万津和最好的开始他们的实验,

从狗取出


胰腺。这导致了以下结果:



?



血糖升高



?



口渴,多喝水,多喝水。



?



变得越来越弱对另一只狗进行试验 ,


万津


和贝佳手术结扎胰腺,停止营养的流动,


使胰腺退化。


过了一段时间,


他们将胰脏


切除,


将其切片并冻结在水和盐的混合物


中。当冰块 半冻时,将其磨碎并过滤。分


Banting


and


Best


surgically


ligated


the


pancreas,


stopping


the


flow of nourishment,


so that the pancreas degenerated. After a


while,


they


removed


the


pancreas,


sliced


it


up


and


froze


the


pieces in a mixture of water and salts. When the pieces were half


frozen, they were ground up and filtered. The isolated substance


was named “isletin”.



The extract was injected into the diabetic dog. Its blood glucose


level


dropped,


and


it


seemed


healthier


and


stronger.


By


giving


the


diabetic dog a few injections a day, Banting and Best could keep it


healthy and free of symptoms. Banting and Best showed their result


to


Macleod,


who


was


impressed


but


he


wanted


more


tests


to


prove


that their pancreatic extract really worked. For the increased testing,


离的物质被命名为“通报”。



将提取 物注射到糖尿病狗中。


其血糖水平


下降,


似乎更健康和更强。


通过给糖尿病狗每


天注射几次,


Banting



Best

可以保持健康和


没有症状。



Ba nting



Best


向麦克劳德展示 了


他们的成果,


他对此印象深刻,


但他 想要进行


更多的测试来证明他们的胰脏提取物确实有


效。为了增 加测试,


Banting



Best< /p>


认识到他


们需要比他们的狗能够提供更多的器官供应,

< p>
并且他们使用来自牛的胰脏来主演。


有了这个


新的 来源,


他们设法产生足够的提取物,


让几


只糖尿病的狗保持活着。


新的结果使麦克劳德


Banting and Best realized that they required a larger supply of organs


than their dogs could provide, and they starred using pancreases from


cattle. with this new source, they managed to produce enough extract


to


keep


several


diabetic


dogs


alive.


The


new


results


convinced


Macleod


that


they


were


onto


something


big.


He


gave


them


more


funds


and


moved


them


to


a


better


laboratory


with


proper


working


conditions.


He


also


suggested


that


they


should


call


their


extract



Now,


the


work


proceeded


rapidly.


In


late1921,


a


third


person biochemist Bertram Collip, joined the team. Collip was given


the task of trying topuri4 the insulin so that it would be clean enough


for


testing


on


humans.


During


the


intensified


testing,


the


team


also


realized


that


the


process


of


shrinking


the


pancreases


had


been


unnecessary.


Using


whole


fresh


pancreases


from


adult


animals


worked just as well.


In


1922


the


insulin


was


tested


on


Leonard


Thompson,


a


14-year-old


diabetes


patient


who


lay


dying


at


the


Toronto


General


Hospital.


He


was


given


an


insulin


injection.


At


first


he


suffered


a


severe,


allergic


reaction


and


further


injections


were


cancelled.


The


scientists


worked


hard


on


improving/


the


extract


and


then


a


second


dose of injections were administered on Thompson. The results were


spectacular.


The


scientists


went


to


the


other


wards


with


diabetic


children,


most


of


them


comatose


and


dying


from


diabetic


keto-acidosis.


They


reacted


just


as


positively


as


Leonard


to


the


insulin extract.


Banting and Macleod were awarded the Nobel Prize in 1923 for


the practical extraction of insulin. They were incensed that the other


members


of


their


team


were


not


included,


and


they


immediately


shared their prize money with Best and Collip. They sold the original


patent to the University of Toronto for one half dollar. They were not


looking for fame or fortune; they wanted to keep sick children from


dying.


They


did


eventually


benefit


financially,


but


that


was


the


last


thing on their minds.


Very


soon


after


the


discovery


of


insulin,


the


medical


firm


Eli


Lilly started large-scale production of the extract. As early as in 1923,


the


firm


was


producing


enough


insulin


to


supply


the


entire


North


American continent. Although insulin doesn't cure diabetes, it's one


of


the


biggest discoveries


in


medicine.


When


it


came,


it


was


like


a


相信他们正在做一些大事。


他给了他们更多的


资金,


把他们搬到了一个有适当工作条件的更


好的实验室。

< p>
他还建议,


他们应该叫他们的提


取物



胰岛素




现在,


工作进展迅速。



1 921


年底,第三人称生物化学家


Bertram

< p>
Collip



入了队伍。



Collip


被赋予尝试


topu ri4


胰岛素


的任务,


以便它足够干净 ,


可以在人体上进行


测试。


在加强检测 过程中,


团队也意识到缩小


胰腺的过程是不必要的。

< p>
使用来自成年动物的


全新鲜的胰腺也同样如此。



1922


年,在


14

< br>岁的多伦多综合医院死亡




尿








·






Leonard


Thompson


)身上测试了胰岛素。他被给了胰

< p>
岛素注射。起初,他遭受了严重的过敏反应,


取消了进一步的注射。科学家 努力改善


/


提取


物,

< br>然后在汤普森进行第二次注射。


结果是壮


观的。科学家去 了另一个病房与糖尿病的孩


子,他们大多是昏迷和死于糖尿病酮酸中毒。


他们的反应和


Leonard


一样积极。



万津和麦克劳德在


1923


年被授予诺贝尔


奖,用于实际提取胰岛素。他们被激怒,其他


队员不包括在内,他们立即用


Best



Collip


分享他们的奖金。


他们把原来的专利卖给了多< /p>


伦多大学半美元。


他们不是为了名利,


他 们想


让生病的孩子免于死亡。


他们最终在经济上受


益,但这是他们心中的最后一件事。



在发现胰岛素后不久,医药公司


Eli


Lilly


就开始大规模生产提取物。早在


1923


年,该


公司就生产出足够的胰岛素供应整个北美大


陆。


虽然胰岛素不能治愈糖尿病,


但这是医学


界最大的发现之一。


一旦到来,


就像是一个奇


迹。


患有严重糖尿病,


只剩下几天生活的人得< /p>


救了。


只要不断得到胰岛素,


他们就能过 上几


乎正常的生活。



使用人胰岛素



1982


年,礼来公司生产了一种人胰岛素


miracle. People with severe diabetes and only days left to live were



Humulin?


),成 为首个获得批准的基因工


saved. And as long as they kept getting their insulin, they could live


程药物产品。


这一重要成就是


20

< br>世纪


50


年代


an almost normal life.


由沃森和克里克对


DNA


进行的经典结构研究


以及由桑格公司提供的胰岛素开始的 一个广


Working with human insulin

泛的基础和应用科学进展网络的结果。


研究人


In


1982,


the


Eli


Lilly


Corporation


produced


a


human


insulin


员不需要依赖动物,


就可以生产出无限制供应


(Humulin?)


that


became


the


first


approved


genetically


engineered


的基因工程胰岛素。

< br>它也没有包含任何动物污


pharmaceutical product. This important achievement was the result of

< p>
染物。


使用人体胰岛素也消除了将任何潜在动


a vast network of basic and applied scientific advances that began in


物疾病转移到胰岛素中的担忧。尽管 从


20



the 1950s with the classic structural studies on DNA by Watson and



80


年代开 始,公司仍然出售少量由动物产


Crick


and


on


insulin


by


Sanger.'


Without


needing


to


depend


on


生的胰岛素(主要是猪),但是胰岛素使用者


animals, researchers could produce genetically engineered insulin in


越来越多地转向通过重组


DNA


技术形成的人


unlimited


supplies.


It


also


did


not


contain


any


of


the


animal


contaminants.


Using


human


insulin


also


took


away


any


concerns


about


transferring


any


potential


animal


diseases


into


the


insulin.


While companies still sell a small amount of insulin produced from


animals



mostly


porcine



from


the


1980s


onwards,


insulin


users


increasingly


moved


to


a


form


of


human


insulin


created


through


recombinant DNA technology.


Insulin


is


a


protein


consisting


of


two


separate


chains


of


amino


acids,


an


A


above


a


B


chain,


that


are


held


together


with


disulfide


bonds.


The


insulin


A


chain


consists


of


21


amino


acids


and


the


B


chain


has


30.


Before


becoming


an


active


insulin


protein,


insulin


is


first produced as preproinsulin. This is one single long protein chain


with


the


A


and


B


chains


not


yet


separated,


a


section


in


the


middle


linking the chains together and a signal sequence at one end telling


the


protein


when


to


start


secreting


outside


the


cell.


After


preproinsulin,


the


chain


evolves


into


proinsulin,


still


a


single


chain


but


without


the


signaling


sequence.


Then


comes


the


active


protein


insulin, the protein without the section linking the A and B chains. At


each


step,


the


protein


needs


specific


enzymes


to


produce


the


next


form of insulin.


Lilly


has


prepared


human


insulin


by


two


different


means'


by


transforming


human


proinsulin


into


human


insulin.


In


the


first


method,


the


two


insulin


chains


are


produced


separately.


Manufacturers


need


the


two


mini- genes:


one


that


produces


the


A


chain and one for the B chain. Since the exact DNA sequence of each


chain


is


known,


they


synthesize


each


mini-gene's


DNA


and


insert


them


into


plasmids.


The


recombinant,


newly


formed,


plasmids


are


then transformed into bacterial cells. During a fermentation process,


the millions of bacteria harboring the recombinant plasmid replicate


roughly


every


20


minutes


through


cell


division,


and


each


expresses


the


insulin


gene.


After


multiplying,


the


cells


are


taken


out


of


the


fermentation tanks and broken open to extract the protein chains. The


two


chains


are


then


mixed


together


and


joined


by


disulfide


bonds


through


the


reduction-reoxidation


reaction.


Although


the


chain


combination


procedure


worked


quite


well,


the


proinsulin


approach


required


fewer


processing


steps


and,


consequently,


superseded


the


胰岛素形式。



胰岛素是一种蛋白质,


由两条独立的氨基


酸链组成,一条


B< /p>


链以上的


A


链与二硫键结


合在一起。胰岛素


A


链由


21


个氨基酸组成,


B


链有


30


个。


在成为活性胰岛素蛋白质之前,


胰岛素首先作为前胰岛素原产生。


这是一个单


链长的 蛋白质链,


A


链和


B

< br>链还没有分开,



间的一段链接在一起,


信号序列的一端告诉蛋


白质何时开始在细胞外分泌。前胰岛素原后,

< p>
链发展成胰岛素原,


仍然是单链,


但没有信号


序列。然后是活性蛋白质胰岛素,不含连接


A



B


链的部分的蛋白质。


在每个步骤 中,


蛋白


质都需要特定的酶来产生下一种形式的胰岛

< p>
素。



礼来公司通过两种不同的方式来制备人


胰岛素



-


最初 是通过链式结合的方法,自


1986


年以来,

< br>通过将人胰岛素原转化成人胰岛


素,


第一种方法是分别生 产两种胰岛素链,



因:一个产生


A< /p>


链和一个


B


链,由于每条链


的确切的


DNA


序列是已知的,他们合成每个


小基因的


DNA


并将它们插入到质粒中,然后


转化新形成的重组质粒在发酵过程中,


携带重

< br>组质粒的数百万个细菌通过细胞分裂大约每



20


分钟复制一次,每个细胞表达胰岛素基



;


倍增后,将细胞从发酵罐中取出,打开提


取蛋白质链,


然后将两条链混合在一起,


通过


还原

< p>


-


再氧化反应通过二硫键连接,尽管链


组合过程起作用胰岛素原方法需要较少的处


理步骤,因此在

< p>
1986


年取代了链式方法。将


编码胰岛素原的序 列插入到非致病性大肠杆


菌细菌中。


细菌经过发酵过程,


再生产胰岛素


原。然后用酶将


A


链和


B


链之间的连接顺序


剪 切掉,得到的胰岛素被纯化。



未来



胰岛素的未来有很多可能性。


由于胰岛素


首先被合成,


糖尿病患者需要定期用注射器将

-


-


-


-


-


-


-


-



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