Dependence of Wall Stress in the Human Thoracic Aorta on Age and Pressure
Dependence of Wall Stress in the Human Thoracic Aorta on Age and Pressure
复制标题
人类胸主动脉壁应力对年龄和压力的依赖性
作者：
Hermann Bader
根据27例22~85岁人体胸主动脉的压力-体积图，计算了0~200 mm Hg压力范围内的切向壁应力和切向弹性模数。主动脉在0-100 mm Hg之间的相对体积增量从20岁时的约190%线性下降到85岁时的约40%，而100 mm Hg时的弹性模数从20岁时的10 kg/cm2线性增加到85岁时的42.5 kg/cm2。随着年龄的增长，主动脉壁膨胀性的降低部分被主动脉内容量的增加所补偿，但在较高年龄时，其膨胀性小于适当的缓冲室活动所需的理论值。切向壁应力随年龄呈线性下降，从20岁时的2.5 kg/cm2下降到85岁时的1.2 kg/cm2。由于弹性血管壁上的压力感受器对壁应力做出反应，这一结果意味着要么平滑的肌肉必须不断增加弹性纤维的应力，要么压力感受器必须在一生中调整它们的敏感性以降低壁应力，以便保持不变。在较高年龄时，平滑肌肉的虚弱或压力感受器不能适应较低的压力可能是导致高血压的原因。
The tangential wall stress and the tangential elasticity modulus at pressures from 0 to 200 mm Hg were calculated from pressure-volume diagrams of 27 human thoracic aortas aged 22 to 85 years. The relative volume increase of the aortas between 0 and 100 mm Hg decreased linearly from about 190% at age 20 to about 40% at age 85, whereas the elasticity modulus at 100 mm Hg increased linearly from 10 kg/cm2 at age 20 to 42.5 kg/cm2 at age 85. The decrease of the distensibility of the aortic wall with age was partly compensated by an increase of the internal volume of the aorta but at higher ages the distensibility was less than the theoretical values necessary for a proper buffering chamber activity. The tangential wall stress decreased linearly with age from about 2.5 kg/cm2 at age 20 to about 1.2 kg/cm2 at age 85. Since the pressoreceptors in the wall of the elastic vessels respond to the wall stress, this result means either that smooth muscles must increase the stress of the elastic fibers continuously, or the pressoreceptors must adapt their sensitivity throughout life to lower wall stress so that it will be kept constant. Weakness of the smooth muscles or a failure of the pressoreceptors to adapt themselves to lower stresses at higher ages may be the cause of essential hypertension.