医学专业英语Chapter5RespiratorySystem

1、精品文档Chapter 5Respiratory SystemIn this passage you will learn: The organs of the respiratory system The structure and function of these organs The mechanism of breathing The gas transport and cleaning systemAll living animals must take in oxygen and get rid of carbon dioxide. In the vertebratesanima

2、ls with backbones that get their oxygen from the air, both tasks are performed by special gas-exchange organs called lungs. The lungs provide a place where oxygen can reach the blood and carbon dioxide can be removed from it. They are equipped with tubes and a bellows system for drawing in air from

3、the outside, while the pulmonary veins and arteries circulate blood through from inside. The lungs also have a cleaning system that traps, ejects, or destroys irritants and other harmful substances that travel in with the air.In the simpler cold-blooded amphibians and reptiles, the lungs are two bal

4、loon-like sacs. In active animals that require large amounts of oxygen, especially the warm-blooded birds and mammals , the lungs are a spongy labyrinth of sacs that supply an enormous surface area for the transfer of gases. In the adult human the total lung surface, if flattened out, would be large

5、r than a badminton court, about 100 square yards (83 square meters).Air enters the body through the nose and passes through the nasal cavity, which is lined with a mucous membrane and fine hairs (cilia) to help filter out foreign bodies, as well as to warm and moisten the air. Paranasal sinuses are

6、hollow, air-containing spaces within the skull that communicate with the nasal cavity. They, too, have a mucous membrane lining and function to provide the lubricating fluid mucus. as well as to lighten the bones of the skull and help produce sound.After passing through the nasal cavity, the air nex

7、t reaches the pharynx (throat). There are three divisions of the pharynx. The nasopharynx is the first division, and it is nearest to the nasal cavities. It contains the adenoids, which are masses of lymphatic tissue. The adenoids (also known.精品文档as the pharyngeal tonsils) are more prominent in chil

8、dren, and if enlarged, they can obstruct air passageways . Below the nasopharynx and closer to the mouth is the second division of the pharynx, the oropharynx. The palatine tonsils, two rounded massed of lymphatic tissue, are located in the oropharynx. The third division of the pharynx is the hypoph

9、arynx (also called the laryngopharynx).It is in the hypopharyngeal region that the pharynx, serving as a common passageway for food from the mouth and air from the nose, divides into two branches, the larynx (voice box) and the esophagus.The esophagus leads into the stomach and carries food to be di

10、gested. The larynx contains the vocal cords and is surrounded by pieces of cartilage for support. Sounds are produced as air is expelled past the vocal cords, and the cords vibrate. The tension of the vocal cords determines the high or low pitch of the voice.Since food entering from the mouth and ai

11、r entering from the nose mix in the pharynx, what prevents the passing of food or drink into the larynx and respiratory system after it has been swallowed? Even with a small quantity of solid or liquid matter finding its way into the air passages, breathing could be seriously blocked. A special dete

12、rrent to this event is provided for by a flap of cartilage attached to the root of the tongue that acts like a lid over the larynx. This flap of cartilage is called the epiglottis. The epiglottis lies over the entrance to the larynx. In the act of swallowing, when food and liquid move through the th

13、roat, the epiglottis closes off the larynx, so that these things cannot enter.On its way to the lungs, air passes from the larynx to the trachea (windpipe), a vertical tubeabout 4 12inches long and 1 inch in diameter. The trachea is kept open by 16-20 C-shaped ringsof cartilage separated by fibrous

14、connective tissue that stiffens the front and sides of the tube. Inthe region of the mediastinum, the trachea divides into two branches called bronchi. Each bronchus leads to a separate lung and divides and subdivides into smaller and finer tubes, somewhat like the branches of a tree (see Figure 6-1

15、) .精品文档DiaphragmFigure 6-1The smallest of the bronchial branches are called bronchioles. At the end of the bronchioles are clusters of air sacs called alveoli. Each alveolus is made of a one-cell layer of epithelium. Thevery thin wall allows for the exchange of gases between the alveolus and the cap

16、illaries thatsurround and come in close contact with it. The blood that flows through the capillaries accepts the oxygen from the alveolus and deposits carbon dioxide into the alveolus to be exhaled. Oxygen is combined with a hemoglobin in erythrocytes and carried to all parts of the body.Each lung

17、is enveloped in a double-folded membrane called the pleura. The outer layer of thepleura, nearest the ribs, is the parietal pleura, and the inner layer, closest to the lung, is the visceral pleura. The pleura is moistened with a serous secretion that facilitates the movements of the lungs within the

18、 thorax.The two lungs are not quite mirror images of each other. The right lung, which is the slightlylarger of thetwo, is divided into three lobes, ordivisions, and the left lung is dividedinto twolobes. It is possible for one lobe of the lung to be removed without damage to the rest, which can con

19、tinue to function normally; The uppermost part of the lung is called the apex, and the lowerarea is the base. The hilum of the lung is the midline region where blood vessels, nerves, and bronchial tubes enter and exit the organ.The lungs extend from the collarbone to the diaphragm in the thoracic ca

20、vity. The diaphragmis a muscular partition that separates the thoracic from the abdominal cavity and aids in the process of breathing. The diaphragm contracts and descends with each inhalation (inspiration) .The downward movement of the diaphragm enlarges the area in the thoracic cavity.精品文档and redu

21、ces the internal air pressure, so that air flows into the lungs to equalize the pressure. When the lungs are full, the diaphragm relaxes and elevates, making the area in the thoracic cavity smaller, and thus increasing the air pressure in the thorax. Air then is expelled out of the lungs to equalize

22、 the pressure; this is called exhalation (expiration) . Other parts are also involved in theprocess. The cycle of respiration really begins when the phrenic nerve stimulates the diaphragm to contract and flatten. Also, the intercostal muscles between the ribs aid in inspiration by pulling the ribs u

23、p and out. The measure of how easily the lungs expand under pressure is compliance.Breathing is regulated unconsciously by center in the brainstem. These centers adjust the rate and rhythm of breathing according to changes in the composition of the blood, especially the concentration of carbon dioxi

24、de.Gas Transport. Oxygen is carried in the blood bound to hemoglobin in red blood cells. The oxygen is released to the cells as needed. Carbon dioxide is carried in several ways, but is mostlyconverted to an acid called carbonic acid. The amount of carbon dioxide that is exhaled is important in regu

25、lating the acidity or alkalinity of the blood. If too much carbon dioxide is exhaledby hyperventilation, body fluids tend to become more alkaline, a condition termed alkalosis. If too little carbon dioxide is exhaled as a result of hypoventilation, body fluids tend to become more acid, a condition t

26、ermed acidosis.The cleaningsystem of the lungs has four main components. Liningthe trachea andbronchial tree are cells that secrete mucus, which traps pollutants and bacteria. Also in the bronchi are cells containing tiny cilia, that project into the blanket of mucus and with constant wavelike motio

27、ns push the mucus up out of the airways. Irritating chemicals, stagnant and excessive mucus, and large bits of foreign matter are forcibly ejected as sputum from the bronchi by a cough. Thisthird important cleaning device like breathing, under partial voluntary control is a rapidmuscle contraction a

28、nd bronchial-tube constriction that generates a wind force far stronger than a tornado. Small harmful substances that make their way into the alveoli are destroyed by the fourthline of defense, the macrophages. These are patrolling cells that swallow up foreign particles or destroy them with enzymes

29、.New Words and Phrases.精品文档.精品文档ExercisesA. Discuss the following topics:.精品文档1. Imagine you were lecturing in front of rural health workers on the topic of respiratory system, draw a picture to illustrate the whole system.2. Describe their structures and functions.3. How can epiglottis prevent the

30、passing food and drink into the respiratory system?4. What role does the diaphragm play in the process of breathing?5. What are the four components of the cleaning system? How do they function?B. Fill in the blanks with the words given below and change their forms if necessary.alveolusdiaphragmthora

31、cic cavityparietal pleuramediastinumcapillaryhemoglobingas exchangevisceral pleurapleural spaceThe lungs are two cone-shaped, spongy organs consisting of alveoli, blood vessels, elastic tissue and nerves. Each of the two lungs consists of smaller divisions called lobes; the left lunghastwo lobes, wh

32、ile the right lung is divided into three lobes. In the lungs, ( 1 ) are surrounded by a network of tiny blood vessels called capillaries; oxygen from the lungs passes into these ( 2 ) fordistributionto tissue cells, whilecarbon dioxidefrom the blood passes into the lungs to beexpelled by exhalation.

33、 Once absorbed into blood cells, oxygen becomes attached to ( 3 ) and isreleased to tissue cells as needed. Thus, the primary function of the lungs is to bring air into closecontact with blood, which allows ( 4 ) to occur.The lungs are surrounded by a membrane called the ( 5 ). The space that the lu

34、ngs occupywithin the chest is called the ( 6 ), which is lined by a membrane called the ( 7 ). The parietaland visceral pleurae lie very close to each other; the small space between theses membranes, called the ( 8 ) , is filled with a fluid that prevents friction when the two membranes slide agains

35、t each other during respiration. In the central portion of the thoracic cavity (in the area between thelungs) is a space called the ( 9 ) , which contains the heart. A group of smooth muscles called the( 10 ) separates the lower portion of the thoracic cavity from the abdomen.C. Match Column I with

36、Column n.Column IColumn II.精品文档bronchiole 1 any of the small subdivision of the bronchicompliance 2 the peak portion of the lungsa condition in which there is too much carbon dioxide in thehypoventilation 3 bloodintercostal 4 between the ribsparanasal sinuses 5 air-conditioning cavities in the bones

37、 near the nosea condition in which there is too much carbon dioxide in theacidosis 6 bloodapex 7 weak , inadequate exchange of gasrounded masses of lymph tissue in the oropharynx ( palatinepharynx 8 means roof of the mouth) .alkalosis 9 in agreement withthroat; composed of the nasopharynx, oropharyn

38、x, andpalatine tonsils10laryngopharynx.D. Define the following terms of the respiratory system in line with the text you have just,learned (making use of the vocabulary provided in the brackets if necessary), for exam-ple:the gas needed by cells to release energyOxygen (gas, cell, release energy fro

39、mfrom food in metabolismfood, metabolism)1. mirror image (as seen, right side,as if, left side, vice versa)2. adenoids(lymphatic tissue, nasophar-ynx)3. alveolus(air sac, gas exchange, inrespiration)4. bronchus(main branch, trachea,mediastinum)5. epiglottis ( leaf-shaped, cartilage, larynx, prevent,

40、 trachea)6. hyperventilation(extreme, rapid,.deep, result in, alkalosis)7. diaphragm (dome-shaped, muscle, move, increase, decrease, space, thoracic cavity)8. pharynx ( common, passageway, esophagus, food, air, larynx)9. pleura (double-layered, membrane,visceral pleura, pariatal pleura, tho-racic ca

41、vity)10. sputum ( substance, releases, coughing, clearing the throat, res-piratory tract)精品文档E. Translate the following into English.1.副鼻窦2.口咽3.脊椎动物4.肺泡5.二氧化碳6.肺换气不足7.横膈膜神经8.双重折叠的9.威慑物10.润滑液11.滞痰12.食管13.纵隔14.哺乳动物15.碱中毒16.迷宫17.污染物质18.脑干19.上皮；上皮细胞20.刺激物Passage Two Respiratory Disorders and DiseasesIn

42、this passage you will learn: Various disorders and diseases of the respiratory system Their definitions, causes and treatment.精品文档 Detailed description of the signs and symptoms of chronic obstructive pulmonary disease Medical terms pertaining to the diseases of the respiratory system The respirator

43、y system is subject to a wide variety of disorders and diseases. The most frequent attacks come from common cold and flu viruses. Other diseases that affect the lungs include bacterial infections such as pneumonia and tuberculosis. The lungs are especially vulnerable to allergic dis- eases such as a

44、sthma. There are more serious diseases such as respiratory distress syndrome, em-physema, chronic obstructive pulmonary diseases (COPD), lung cancer, etc.Influenzaand pneumonia.Influenza is a viral disease of the respiratory tract. Differentstrains of the influenza virus have caused serious epidemic

45、s through history. Pneumonia is caused by several different microorganisms. The name represents any inflammation of the lungs caused by in-fection, so an alternate term for pneumonia is pneumonitis. Streptococcal pneumonia usually in-volves one or more lobes of the lung and described as lobar pneumo

46、nia. Other agents of pneumonia localize in the bronchial tubes, causing bronchopneumonia.Pleurisy is severe chest pain accompanying each deep breath in a person with an inflamed pleura, the twin membranes around each lung and lining the chest cavity. Pleurisy can attend pneu-monia or result from dir

47、ect infection of the pleura.Tuberculosis (TB )has increased in recent years along with the rise of AIDS and the appear-ance of resistance to antibiotics in the organism that causes the disease. The name of the diseasecomes from the small lesions, or tubercles, that appear with the infection. The sym

48、ptoms of TB in-clude fever, weight loss, weakness, cough, and as a result of damage to blood vessels in the lungs, hemoptysis, i. e. the coughing up of phlegm (sputum) containing blood. Accumulation of exudatein the alveoli may result in solidificationor consolidation of lung tissue. The tuberculin

49、test isused to reveal tuberculosis infection, PPD (purified protein derivative) is the form of tuberculin commonly used.Asthma . Attacks of asthma result from narrowing of the bronchial tubes. The constriction, a-long with edema, swelling of the bronchial linings, and accumulation of mucus results i

50、n wheezing, extreme dyspnea and cyanosis. Although the cause of asthma is uncertain, foreign particles such aspollen or certain environmental pollutants are believed to be the culprits, which stimulate the smooth muscle of the bronchial tree to releases histamine causing the muscle to contract. The

51、bronchial air-.精品文档waysareconsequentlyrestricted.Treatmentofasthmaincludesremovalofallergens,administration of bronchodilators to widen the airways, and administration of steroids.Respiratorydistress syndrome is a disorder of some prematurely bom infants. The alveoli ofafflicted babies are lined wit

52、h a protein material, limiting the amount of oxygen their blood can re-ceive. The disease is often fatal. Mechanical ventilators can be used to help infants breathe until their lungs become more mature. As a result of some accidents and diseases, such as polio, the res-piratory center or nerves carr

53、ying its impulses may be paralyzed. Treatment may involve cutting ahole through the windpipe and passing a tube attached to a mechanical respirator through the hole. In other cases, the patient may be placed on a heart and lung machine that maintains respiration and heartbeat.Acute pulmonary edema r

54、esults when fluid quickly accumulates in the lungs and fills the alveoli. The fluid buildup is caused by heart trouble that, in turn, produces back pressure in thepulmonary veins and the left atrium of the heart to which they carry oxygen-rich blood from the lungs. A person suffering acute pulmonary edema is suddenly breathless and turns blue because ofoxygen-poor blood. The condition is treated with oxygen, digitalis to strengthen heart action, and diuretics to s