西医英语,第8章免疫系统

医学英语综合教程第二版Unit8第一篇：医学英语综合教程第二版Unit 8诊断学接诊患者的一般方法成功的诊疗要求医生考虑患者常见的复杂的个人、家族因素的和经济条件，保持积极开放的医患关系。

诊断第一步是采集病史和查体，这两项很容易被疏漏和请人代劳。

问诊应实现三大功能：收集信息，对患者情绪给与适当的安慰、指导病人已对其行为产生有益的影响。

通过了解病人的顾虑（心理社会问题）、给予病人倾诉的空间（不要始终占据主动），患者的满意度可以提高。

要确定诊断手段必须遵循诊断检验选取的原则，这些原则确立的基础是检验的特点（敏感性和特异性）、发病率与患病率、可能给病人带来的危害、检验的必要性和性价比。

成功的治疗需要按病人的实际情况进行个体化设计并且得以与良好的医患关系的形成。

指导原则成功的诊疗需建立在“诚实、仁爱、公正、不以医术牟利、保障不以医术作恶”的伦理原则。

西医在重要的医疗决策中——例如绝症病人何时终止治疗等，越来越重视病人的意见。

总之，医生的作用不只是下诊断和开处方；医生具有移情能力，帮助患者及其家属分担重病和死亡带来的压力是更重要的。

“有时能治疗，常常缓解病痛，总是给以安慰”——这句五百年前的法国谚语今天仍然适用。

Francis Peabody也谈到：“治好病人的秘密是关心他们”。

健康维护和疾病预防防病壁纸并更重要。

预防医学分为一级、二级、三级预防。

一级预旨在去除和降低疾病的风险因子（例如，免疫接种，戒烟）。

二级预防推动疾病的早期检测或先兆状态（例如：常规的宫颈巴氏涂片已检测侵袭性癌或者宫颈部位的原位癌，或者结核菌素皮试以确定肺结核病人是否需要化学预防）。

三级预防措施目标是控制已发疾病（例如部分切除乳腺与化疗已清除或控制乳腺局部癌症）。

截至目前，一级预防是最有效最经济的疾病控制手段，然而大多数医生在（向病人宣教）可预防的疾病是做的仍然不够。

医生可以有效降低疾病风险因子，健康维护与疾病预防往往始于门诊。

活动不足与静态的生化方式常见慢性病患者死亡的原因中28%由静态的生活方式导致。

第八章免疫系统免疫是机体对抗原物质产生的一种生物学反应，称为免疫应答。

其生理功能是识别、清除抗原物质，如病原体及其产物、自身的衰老细胞和恶变的细胞等。

将执行免疫功能的组织结构统称为免疫系统(immune system)。

免疫系统由免疫细胞、淋巴组织、免疫器官组成。

免疫系统和其它系统一样，也受神经—内分泌系统的调节。

一、免疫细胞参与免疫应答的细胞主要有两大类，即淋巴细胞和抗原提呈细胞。

淋巴细胞是免疫系统中的核心成分，是参与特异免疫应答的主要细胞。

抗原提呈细胞具有捕获抗原的能力，在免疫应答中起重要作用。

此外，红细胞、有粒白细胞、肥大细胞、血小板等在一些免疫应答中亦具有一定的作用。

(一)淋巴细胞淋巴细胞在体内分布很广，普遍存在于血液、淋巴液、淋巴组织及免疫器官内．人类淋巴细胞主要来源于骨髓的淋巴干细胞。

近十几年来研究发现，淋巴细胞是机体内种类繁多、功能各异的一个复杂的细胞群体。

根据它们的发育过程、细胞膜表面标记、寿命长短及功能不同，将淋巴细胞分为T细胞、B细胞、K细胞和NK细胞四类。

1、T细胞(T淋巴细胞) 在循环血中，T细胞约占淋巴细胞总数75%。

T细胞来源于骨髓的淋巴干细胞，在胚胎时期到达胸腺，在胸腺微环境的培育下增殖、分化成具有免疫活性的小淋巴细胞，称胸腺依赖淋巴细胞(thymus dependent lymphocyte，，T细胞)。

该细胞经血液循环移至周围淋巴组织或免疫器官的胸腺依赖区定居，经抗原刺激后，T细胞再次分裂、分化，形成大量效应性T细胞和部分记忆T细胞。

效应性T细胞具有与相应抗原发生免疫应答的能力。

目前已知效应性T细胞至少可分为三个亚群：①辅助性T细胞，形状似小淋巴细胞，数量较多，它可协助T细胞或B细胞识别抗原，引起和增强免疫应答。

②抑制性T细胞，体积略大，数量较少，它能抑制免疫应答，与辅助性T细胞共同凋节免疫应答强弱。

②细胞毒性T细胞．与抑制性T细胞形态相似，它受抗原澈活后可大量增殖，是行使细胞免疫的主要效应细胞，其主要功能是直接杀伤靶细胞或分泌淋巴因子间接杀伤靶细胞。

CHAPTER 5 IMMUNE SYSTEMI. INTRODUCTION1. As we perform our everyday activities, we are exposed to different types of harmful agents that can cause disease or injury. Good thing we have a built-in mechanism to protect us from these agents. This mechanism is provided to us by our immune system.2. The immune system is a collection of structures, cells, and cell products that can fight external or internal agents harmful to the body. These components and other protective factors of the body will be the topic of this chapter.3. Immunology is the study of the normal functions and diseases of the immune system. Below are some of the most common words used in immunology:TERM DESCRIPTIONImmune (immun/o) An individual’s ability of being insusceptible to or being protected from a harmful agent, disease or some other condition.Immunity condition or state of being immune; also used to refer to the resistance of thebody to develop a certain diseasePathogen This refers to any agent that can cause disease, especially infectious ones. Antigen any foreign body or agent that can cause an immune reaction/response inside ourbodies. It could be infectious or non-infectious.II. FORMS OF IMMUNITY: INNATE AND ADAPTIVE1. The immune system has two levels of immunity – innate and adaptive. The two differs in the components and mechanisms by which they provide protection to the body.2. Innate immunity is provided by structures and cells that exist naturally in our bodies. This form of immunity is NONSPECIFIC and usually occurs immediately after the time of contact with the pathogen. Below are the components of this type of immunity.2.1. Physical and Chemical Barriers – These are structures or substances in the body that can offer some protection against pathogens.2.1.1. The skin is an important physical barrier that protects the entire body from external pathogens.2.1.2. The acid in the stomach serves as a natural killer or destroyer of pathogens that enter the digestive tract.2.2. White Blood Cells (Leukocytes)– They act as phagocytes that ingest pathogens, and therefore, stop them from doing further injury in the body. (Please read on the functions of these cells in the chapter about the circulatory system – lymphatic system.)2.3. Natural killer cells – These are a type of lymphocytes that directly attack and cause destruction of virus-infected cells and cancer cells.2.4. The Complement System – This system contains protein substances (in the form of enzymes and antibodies) that either cause direct lysis (destruction) of the pathogens, or make them easily available for engulfment by phagocytes. (This is also considered part of adaptive immunity.)2.5. Natural microbial flora – This refers to the microbes (mostly bacteria) that naturally live naturally on/in any part of the body and do not cause any form of harm or disease unless some factors lead them to. In their natural habitats, they produce substances that help protect the body from other forms of pathogens. However, should it happen that they get into or invade other areas not their own, diseases may occur.3. Adaptive or acquired immunity is provided by lymphocytes of the body. This form of immunity is capable of providing body defenses that are SPECIFIC to certain pathogens/antigens. There are two types of this form of immunity.3.1. Cell – mediated immunity – This type is brought about by the activity of T lymphocytes. T – lymphocytes can attack cells (killer T cells), or help other immune cells improve their functions (helper T- cells). Cytokines are substances that helper T-cells produce and functions enhance the immune capabilities of other defense cells.3.2. Humoral – mediated immunity – This type is brought about by the activity ofB lymphocytes. B lymphocytes transform into plasma cells that are capable of producing antibodies.3.2.1. Antibodies are protein substances that can inactivate the action ofantigens. An antibody (immunoglobulin) is highly specific for its antigen, similar to a lock and its key.3.2.2. Antibodies are formed whenever antigens enter the body.3.2.3. There are types of antibodies (immunoglobulins) produced by plasmacells. Please see the table below for details.Type Description Where most commonly foundBlood and body fluidsIg G Most abundant antibody in the body; late responseantibody; signifies previous infectionBlood and lymphIg M Early response antibody (first line); signifies arecent infectionIg A Provide mucosal immunity GIT, GUT, membranes &secretions (tears, saliva, breastmilk)Ig D An antigen receptor for B cells On B cellsIg E Related to allergic and parasitic reactions Tissues of the body3.3. Both types of adaptive immunity produce memory cells that go into action in the event of attacks caused by the same type of antigen.III. CLASSIFICATION OF IMMUNITY1. Immunity can be classified in other ways. It could be active or passive; natural or artificial.2. Active immunity occurs when the body develops defenses against an antigen after being exposed to it. The immunity that results is said to be long-term.2.1. Natural active immunity occurs in the setting of an incidental contact with a pathogen, like an infection acquired from the environment.2.2. Artificial active immunity occurs after intentional administration of an antigen or part of an antigen, in the hope of developing resistance against it in the future. An example is vaccination for hepatitis B.3. Passive immunity occurs when an individual is provided with formed substances to protect him from an antigen. These substances have been produced by another source. This type of immunity is of short-term duration.3.1. Natural passive immunity is exemplified by the transfer of antibodies from the mother to her fetus during pregnancy.3.2. Artificial passive immunity is exemplified by the provision of an anti-toxin for tetanus right after an injury.IV. PROBLEMS OF THE IMMUNE SYSTEM1. Like other systems in the body, the immune system can also be affected by diseases. Commonly observed disease processes of the system include immunodeficiency and hypersensitivity.2. Immunodeficiency, in simple terms, is the condition wherein the immune system is either weak or has lost its ability to defend the body. Damage to any component of the immune system can lead to this condition.2.1. Agammaglobulinemia is the most common primary immunodeficiency disease. It is a genetic disorder that is characterized by the inability of B lymphocytes to produce immunoglobulins. It commonly affects males.2.2. The human immunodeficiency virus (HIV)is an agent that destroys some T cells of the body. This ultimately leads to the popular condition known as AIDS.3. Hypersensitivity is an excessively abnormal reaction experienced by an individual after being exposed to a certain stimulus. The white blood cells, in this case, are in a hyperactive state. Asthma is a common example of a hypersensitive reaction.3.1. Hypersensitive reactions are classified into 4 types. Please see the table below for details.Type Description ExamplesI - Immediate or Anaphylactic Mediated by IgE; reaction usually produces signs andsymptoms in 15-30 min.Asthma, Allergic rhinitisII – Cytotoxic Mediated by IgM & IgG; could happen to minutes tohours; involves direct assault and destruction of thetargeted cells Autoimmune Hemolytic Anemia; pemphigusIII – Immune- complex Involves an antigen-antibody complex that deposits ontissues; variable duration (hours, days, weeks)Serum sicknessIV – Delayed Mediated by T cells & macrophages; the reaction isrelatively slowTuberculosis (TB)3.2. Autoimmunity refers to the phenomenon wherein the immune system mistakes parts of the body (cells and tissues included) for antigens. The immune system sees these parts of the body as foreign, and therefore, attacks them. It’s like the body is attacking itself (this is why we use the prefix “auto-” which means “self”).For further reading, please see the list of references included at the last part of this book.POST-READING LEARNING ACTIVITIESI. CHAPTER SUMMARYMake a summary of the chapter using a concept map or numbered outline. Make your summary concise and easily retrievable for future use. Use the space provided below for this purpose.II. COGNITIVE AND SKILL RELATED EXERCISESA. Writing Medical Terms - Identify the term briefly described in each item. Write the best answer. Be careful of your spelling.Brief Description Answer Brief Description Answer1. acute allergic reaction to an antigen 6. antibody-producing cells2. diseases wherein the immune system attacks the body’s own cells 7. defense cells that directly attack cancer and virus-infected cells3. surgical removal of the spleen 8. tumor of the lymph glands4. general term for defense cells that can engulf and digest unwanted materials 9. movement of defense cells through intact blood vessel walls5. cells that are capable of “remembering” antigens 10. defense cells that respond first to any injuryB. Word Analysis - Break each term into its component parts. Next, provide the meaning of each part. Lastly, write the formal definition of the term.e.g. extracardiac extra/cardi/acextra-= outside; cardi- = heart; -ac = adjective suffix1. interleukin2. immunoglobulin3. thymectomy4. monoclonal5. immunosuppressionC. Acronyms - Write out the full meanings of the following abbreviations/acronyms. (Hint: Search for those abbreviations that are related to the topic covered in this chapter.)1. ELISA2. SLE3. IgM4. PMN5. MCTDD. Diagramming Processes - Create a diagram showing the phenomena/mechanisms involved in the processes given below. Use short phrases and arrows for your diagram. You may make use of other symbols if deemed necessary. Provide a legend for the symbols that you would be using.1. type II hypersensitivity2. autoimmune mechanism (select a disease)E. Drawing/Illustration - Create illustrations/drawings for the items given below. Make your drawings as sensible and realistic as possible. LABEL your drawings properly.1. mature white blood cells of the body2. agglutination3. phagocytosis4. antigen presentationF. Application – Supply the needed answers.After transplant procedures, it is pretty common to given immunosuppressive drugs to eliminate or minimize the effects of graft-versus-host reaction. Glucocorticoids are one of the classes of drugs used for this purpose. Let us suppose you are planning to give glucocorticoids to your patient after kidney transplant. How are you going to explain to him the effects of these drugs on his immune system? Use a diagram for your answers.III. REFLECTION AND ATTITUDE BUILDING1. In what ways was this chapter relevant to you as a medical student, and, in your future career as a doctor? (Recall the details you have learned and exercises you did in this chapter.)2. Was this chapter able to encourage you to search greater meaning in your study of medicine? Why do you say so?3. Do you have suggestions on how to enhance further your learning of the topic given in this chapter? Kindly cite at least two of them.4. General Comments: Write as freely and as much as possible. You may write about the following: problems you encountered while studying this lesson, the teaching and learning methods used, or things not covered by the chapter but are relevant to you. Thank you very much.。

第8章免疫系统器官淋巴细胞来源初级淋巴器官胸腺结构功能胸腺激素法氏囊结构功能肠道黏膜集合淋巴结结构功能淋巴腺复合体骨髓次级淋巴器官淋巴结结构淋巴细胞循环种属差异对抗原应答反应血淋巴结脾脏白髄结构对抗原应答反应其他次级淋巴器官尽管抗原是由树突状细胞、巨噬细胞和B细胞捕获和加工的，获得性免疫应答实际上主要是由淋巴细胞完成的。

淋巴细胞是一种小而圆的细胞，主要存在于脾脏、淋巴结和胸腺等器官内（图8-1），因此将这些器官称为淋巴器官。

淋巴细胞表面有抗原受体，能对抗原作出识别和应答。

（因此也可认为它们是“抗原致敏”细胞。

）淋巴细胞最终可产生抗体及细胞介导的免疫应答。

淋巴器官为淋巴细胞、抗原递呈细胞和外来抗原之间相互作用提供了所需环境，同时也是淋巴细胞加工抗原的场所。

必须谨慎调节免疫应答过程。

淋巴细胞须经过选择，以使它们的受体只能结合外来抗原。

每个淋巴细胞的应答反应也需进行调节，使它们既能充分发挥功效但又不会对机体环境造成损害。

可根据功能的不同对淋巴器官进行分类。

淋巴器官的功能有：产生淋巴细胞；调节淋巴细胞生产；提供捕获、加工抗原的环境；增加加工过抗原与抗原致敏细胞间相互接触及作用的机会（图8-2）。

图8-1. 猪的主要淋巴组织。

图8-2. 淋巴器官是淋巴细胞群发生、发育及发挥功效的场所。

淋巴细胞的来源淋巴干细胞首先形成于胎儿网膜、肝脏和卵黄囊。

在胎儿晚期和成年动物，这些干细胞主要存在于骨髓中。

成年哺乳动物的骨髓具有多种功能。

骨髓是重要的造血器官，出生后一切血细胞，包括淋巴细胞均源于骨髓中干细胞。

在一些哺乳动物，如灵长类，骨髓还是一个初级淋巴器官（是新生淋巴细胞发育成熟的场所）。

与脾脏、肝脏和淋巴结一样，骨髓含有许多树突状细胞和巨噬细胞，可除去血液中的外来物质。

骨髓中还含有大量的抗体生成细胞，是抗体的主要产生来源。

由于这些多样功能，可将骨髓分为造血部分和脉管部分。

这两部分交替分布，像蛋糕片一样，呈楔形分布于长骨内。