【正文】 als consist of only a single cell. Others are posed of many billions of cells. 從細(xì)胞開始，我們能夠從最簡單到最復(fù)雜的水平來研究機(jī)體。人體的每個系統(tǒng)都有其特定功能，但是，請記住這里:機(jī)體是作為一個整體來發(fā)揮作用的，沒有哪個系統(tǒng)能夠獨(dú)立于其他系統(tǒng)而存在，是整體系統(tǒng)共同作用保持了機(jī)體內(nèi)部的穩(wěn)定狀態(tài)，即體內(nèi)平衡。頭發(fā)及指甲是皮膚的附屬結(jié)構(gòu)。（約37攝氏度）。皮膚防御外來侵襲，防止過多水分蒸發(fā)。s temperature close to 37 176。 The skin is a plete layer that protects the inner structures of the body, and it is the largest of the body39。 The female productive system is responsible for producing and transporting ova (the female sex cells), eliminating ova from the body when they are not fertilized by sperm, nourishing and providing a place for growth of an embryo when an ovum is fertilized by sperm, and nourishing a newborn child. The female reproductive system also produces the female sex hormones, estrogen and progesterone, which regulate the development of breasts and other bodily characteristics of the mature female. 女性生殖系統(tǒng)產(chǎn)生、輸送卵子（女性性細(xì)胞），將未受精的卵子排出體外，而當(dāng)精、卵結(jié)合時，女性生殖系統(tǒng)培養(yǎng)、提供胚胎生長場所，并孕育新生兒。男性生殖系統(tǒng)產(chǎn)生、輸送、維持能存活的精子（男性性細(xì)胞）。這些神經(jīng)輸送來自各種感覺器官的信息。脊髓由脊柱保護(hù)。神經(jīng)系統(tǒng)更高級的功能是整合、處理信息。腦的偏下部位控制著諸如呼吸、心跳、體溫、饑渴的基本活動。胰腺不僅分泌消化酶，而且分泌胰島素和高血糖素，這兩種激素控制機(jī)體的糖分及淀粉的消耗。性器官（卵巢、睪丸）分泌性細(xì)胞和性激素，這些激素控制著男性和女性的某些特征。s use of sugar and starches. 另一個腺體，甲狀腺，位于鎖骨之間。 Another gland, the thyroid, is located between the collar bones. Its hormone controls the rate of the body39。它至少分泌八種激素，這些激素對人體生長、肝功能及性器官發(fā)育有影響。激素是由各種內(nèi)分泌腺體制造，并直接被釋放入血流 A major gland is the pituitary, which is located under the brain in the middle of the head. It produces at least eight hormones, which affect growth, kidney function, and development of the sex organs. Because some of the pituitary39。 The endocrine system. The two systems that control body activities are the endocrine system and the nervous system. The former exerts its control by means of chemical messengers called hormones. Hormones are produced by a variety of endocrine glands, which release the hormones directly into the blood stream. 內(nèi)分泌系統(tǒng)。 The fluid that leaves the kidneys, known as urine, travels through a tube called the ureter to the bladder. The bladder holds the urine until it is voided from the body through another tube, the urethra. 從腎流出的液體，即尿，通過輸尿管人膀胱。身體是通過讓’腎過濾血液來做到這一點(diǎn)的。大部分液體在大腸內(nèi)被吸收，相對干化的殘余物被排出體外。 The liquid remainder of the food enters the large intestine, or colon, which is about 12 feet ( meters) long. It is more than twice as wide as the small intestine. In the large intestine most of the fluid is absorbed, and the relatively dry residues are expelled. 液狀的剩余食物進(jìn)入大腸，或結(jié)腸，它大約有12英尺（）長。一個成年人的小腸有21英尺（）長。這些酶完成食物的化學(xué)分解。The liquified food gradually passes into the small intestine. In the first part of the small intestine, called the duodenum, enzymes from the pancreas are added. These enzymes plete the chemical breakdown of the food. The digestion of fat is aided by bile, which is made in the liver and stored in the gall bladder. The small intestine of an adult is about 21 feet ( meters) long. Most of its length is devoted to absorbing the nutrients released during these digestive activities. 液體化食物逐漸進(jìn)入小腸。接著，食物經(jīng)食管人胃。 Food enters through the mouth, where chewing and saliva start to break it up and make it easier to swallow. Next, the food travels down through the esophagus to the stomach. Contractions of the stomach39。食物和液體在消化道里被吸收，在腸道里移動時，被分解成小分子物質(zhì)后再進(jìn)入循環(huán)系統(tǒng)。從空氣攝取的氧氣流經(jīng)這些肺泡壁內(nèi)的毛細(xì)血管流入血液，血液再經(jīng)肺泡把釋放出的二氧化碳排出體外?？諝饨?jīng)鼻腔、口腔人喉管、氣管。脾是一個過濾血液的大淋巴器官。一些細(xì)胞周圍的體液不是直接回流入血管通道，這種體液叫淋巴液，它是流經(jīng)另一個管道系統(tǒng)——淋巴管而回流人心臟。靜脈輸送血液返回心臟。一半吸收來自肺部的血液，并將血液運(yùn)送到機(jī)體的其余部位，另一半使流經(jīng)全身的血液回流人肺。血液也是機(jī)體防御系統(tǒng)的一個部分，血液中有抗體及白細(xì)胞來防止機(jī)體受到外來的侵襲。循環(huán)系統(tǒng)運(yùn)送有用物質(zhì)，排泄廢物。The circulatory system. All parts of the body must have nourishment and oxygen in order to function and grow, and their waste products must be removed before they accumulate and poison the body. The circulatory system distributes needed materials and removes unneeded ones. It is made up of the heart, blood vessels, and blood, which together make up the cardiovascular system. The blood is also part of the body39。心臟收縮和平滑肌收縮就不是被意識所控制的。結(jié)締組織使肌肉末端附著于不同的骨面上，所以當(dāng)肌肉收縮時，兩骨彼此靠近而產(chǎn)生運(yùn)動。The muscular system allows the body to move, and its contractions produce heat, which helps maintain a constant body temperature. Striated muscles can be consciously controlled. The ends of these muscles are attached to different bones by connective tissue bands so that when the muscle contracts, one bone moves in relation to the other. This makes it possible to move the whole body, as when walking, or to move just one part of the body, as when bending a finger. Contractions of the heart and smooth muscles are not under conscious control. Smooth muscles are found in the walls of organs such as the stomach and the intestines and serve to move the contents of these organs through the ，肌肉收縮產(chǎn)生的熱有助于維持一個恒定的體溫。它把肋骨與胸骨連結(jié)起來，也是鼻腔與內(nèi)耳的結(jié)構(gòu)基礎(chǔ)。s skeleton is made of cartilage that is gradually replaced by bone as the infant grows into an adult.軟骨是一種比一般骨更具韌性的物質(zhì)。如果一根骨的球形末端插入另一根骨的臼槽里，大輻度的運(yùn)動（如肩關(guān)節(jié)、髖關(guān)節(jié)）即成為可能。顱骨不能運(yùn)動，是由于骨與骨之間的連接太緊密。許多長骨里有一個內(nèi)層間隙，里面充填著骨髓，這即是血細(xì)胞的制造場所。人體有206根骨頭。The skeletal system is made of bones, joints between bones, and cartilage. Its function is to provide support and protection for the soft tissues and the organs of the body and to provide points of attachment for the muscles that move the body. There are 206 bones in the human skeleton. They have various shapes long, short, cube shaped, flat, and irregular. Many of the long bones have an interior space that is filled with bone marrow, where blood cells are made.骨骼系統(tǒng)由骨、關(guān)節(jié)以及軟骨組成。 Anatomists find it useful to divide the human body into ten systems, that is, the skeletal system, the muscular system, the circulatory system, the respiratory system, the digestive system, the urinary system, the endocrine system, the nervous system, the reproductive system and the skin. The principal parts of each of these systems are described in this article.解剖學(xué)家發(fā)現(xiàn)把整個人體分成骨骼、肌肉、循環(huán)、呼吸、消化、泌尿、內(nèi)分泌、神經(jīng)、生殖系統(tǒng)以及感覺器官的做法是很有幫助的。研究人體結(jié)構(gòu)的科學(xué)叫解剖學(xué)；研究人體功能的科學(xué)叫生理學(xué)。 the study of the body39。.. .. .. ..Chapter 1 Passage 1 Human Body