Blood pressure refers to the force exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The term blood pressure generally refers to arterial blood pressure, i.e., the pressure in the larger arteries. Blood pressure is most commonly measured via a sphygmomanometer, which uses the height of a column of mercury to reflect the circulating pressure. Although many modern blood pressure devices no longer use mercury, blood pressure values are still universally reported in millimetres of mercury (mmHg). It consists of two parts: the systolic pressure and the diastolic pressure.

　　血压是指血液循环时作用于血管壁的压力，为生命体征之一。血压这一术语一般是指动脉血压，即大动脉血压。最常用的测压工具是血压计，它根据水银柱的高度来反映血液循环时所产生的压力。虽然现在的很多血压器具已不再使用水银，但毫米汞柱（mmHg）依然是世界通用的测压单位，它包括两个部分：包括收缩压和舒张压

　　The systolic pressure is defined as the peak pressure in the arteries, which occurs near the beginning of the cardiac cycle; the diastolic pressure is the lowest pressure (at the resting phase of the cardiac cycle). The average pressure throughout the cardiac cycle is reported as mean arterial pressure; the pulse pressure reflects the difference between the maximum and minimum pressures measured. form www.med66.com

　　心动周期开始时动脉出现的最高值为收缩压，心动周期静息期出现的最低压为舒张压，心动周期全过程中的平均压力为平均动脉压。最高和最低值之差为脉搏压。

　　Typical values for a resting, healthy adult human are approximately 120 mmHg systolic and 80 mmHg diastolic (written as 120/80 mmHg, and spoken as "one twenty over eighty"). These measures of blood pressure are not static, but undergo natural variations from one heartbeat to another and throughout the day (in a circadian rhythm); they also change in response to stress, nutritional factors, drugs, or disease. Hypertension refers to blood pressure being abnormally high, as opposed to hypotension, when it is abnormally low.

　　健康成人静息时的典型血压约为收缩压120mmHg，舒张压80mmHg，写作120/80 mmHg，血压值并非静止不变，一天之间（生理节律）、前后次搏动都会自然而然地有所变化，紧张、营养因素、药物或疾病等也会导致其变化。血压超出正常为高血压，与低血压相对，后者是指血压低于正常值。

　　Blood pressures can be measured invasively or non-invasively. The former is usually restricted to a hospital setting. The latter is simpler and quicker and less unpleasant and painful for the patient, using a stethoscope, a sphygmomanometer, and a cuff of appropriate size.

　　测量血压有两种方法：侵入式和非侵入式。前者严格限于医院，后者则较简单快捷，病人的不适及痛苦也小，通常包括听诊器、血压计和一个大小合适的袖袋。