医学英语综合教程课文和翻译新

Unit2. Cells and Aging

Aging is a normal process accompanied by a progressive alteration of the body’s homeostatic adaptive responses; the specialized branch of medicine that deals with the medical problems and care of elderly person is called geriatrics.

衰老是一种正常的生理过程，伴有机体内环境稳定适应性应答的进行性改变。

研究老年人的健康问题和保健的一门特殊医学分支被称作老年病学

The obvious characteristics of aging are well known; graying and

loss of hair, loss of teeth, wrinkling of skin, decreased muscle mass, and increased fat deposits. The physiological signs of aging are gradual deterioration in function and capacity to maintain a constant internal environment (homeostasis) in response to changes in temperature, diet, and oxygen supply. These sings of aging are related to a net decrease in the number of cells in the body and to the dysfunctioning of the cells that remain.

衰老的明显特征众所周知：头发花白和脱落，牙齿脱落，皮肤起皱，肌肉减少，脂肪积存增加。衰老的生理征兆是机体对环境刺激反应的功能和能力的逐渐退化如

同维持机体内环境稳定来应对温度，饮食和氧气供应改变的能力减退一样，机体新

陈代谢也减慢了。衰老的这些迹象与机体中细胞数目的净减少以及存余细胞的功能

紊乱有关。

The extracellular components of tissues also change with age. Collagen fibers, responsible for the strength in tendons, increase in number and change in quality with aging. These changes in the collagen

of arterial walls are as much responsible for their loss of

extensibility as are the deposits associated with atherosclerosis, the deposition of fatty materials in the arterial walls. Elastin, another extracellular component, is responsible for the elasticity of blood vessels and skin. It thickens, fragments, and acquires a greater

affinity for calcium with age – changes that may also be associated

with the development of atherosclerosis.

组织的细胞外成分也随着年龄的变化而变化。负责肌腱力量的胶原纤维的数量

增加，而质量却随着衰老降低。动脉壁上的胶原质的变化与动脉壁伸展性丧失有关，正如动脉粥样硬化，即动脉壁脂肪物质堆积造成动脉壁伸展性缺失一样。弹性蛋白是另一种细胞外成分，与血管和皮肤的弹性有关，随着年龄的变化，它变粗，易断裂并且与钙有很大的亲和力，这些变化可能也与动脉粥样硬化的发生有关。

Glucose, the most abundant sugar in the body, may also play a role

in the aging process. According to one hypothesis, glucose is added, haphazardly, to proteins inside and outside cells, forming irreversible

cross-links between adjacent protein molecules. As a person ages, more cross-links are formed, and this probably contributes to the stiffening and loss of elasticity in aging tissues.

葡萄糖是机体中含量最多的糖类，它在衰老的过程中可能也起作用。根据一个假说，随机地在细胞内外蛋白质上添加葡萄糖，结果会在相邻蛋白质分子之间形成不可逆的交联。随着人的衰老，会形成更多的交联，这很可能就是造成衰老的组织僵硬及弹性丧失的原因。

Although many millions of new cells normally are produced each minute, several kinds of cells – heart cells, skeletal muscle fibers, nerve cells - cannot be replaced, Experiments have shown that many other cell types have only a limited capability to divide. Cells grown outside the body divide only a certain number of times and then stop. The number of divisions correlates with the donor/s age and with the normal life span of the different species from which the cells are obtained. These observations provides strong evidence for the hypothesis that cessation of mitosis is a normal, genetically programmed event. According to this view, an “aging” gene is part of the genetic blueprint at birth, and

it turns on at a preprogrammed time, slowing down or halting processes vital to life.