POSTURAL EFFECTS ON HEART-RATE AND BLOOD-PRESSURE

摘要: The slowed pulse-rate in the horizontal posture as compared with sitting, and quicker rate standing depend on wholly different mechanisms may vary independently. The relative amount of muscular contraction present these postures has no appreciable effect. The sitting-lying difference is due to hydrostatic influence acting mainly, if not wholly, through carotid sinus reflex. Pronounced variation activity this reflex occur at periods day days; such variations are associated absence or marked occurrence a difference. When active, change from lying vice versa, causes pulse-rate; incidence gravity splanchnic area changes tension abdominal wall tone back-muscles, etc., evidently unimportant regards pulse-rate, which affected by adjustment, compensatory blood-pressure, when trunk moved into vertical position. The sitting-standing altered position thighs, vertical, two postures. leg unimportant. In position, prone, lateral, supine, thighs ineffective; upper end elevated certain extent horizontal, affect pulse-rate. The increased heart-rate accounted for capacious area, determining lowering aortic pressure, does normal subjects; nor acceleration dependent wall, trunk-muscles, upon muscle-groups lower limbs. The standing-lying equals combined standing-sitting differences. While latter nil, differences equal. These often parallel fashion. pulse-slowing postures, e.g. foot-up standing, inclination thigh. The squatting cause slowing acceleration, sometimes showing definite relation Compression tissues vessels involved position. Artificially induced vascular turgescence limbs sitting but attended increase pulse-rate. Artificial occlusion circulation limb leads suspension postural effects pulse-rate. Some bending ways described. While motionless decidedly faster—5 10 beats—than slight, continued movements kept up limbs. action directly reflexly heart-rate, pressure. Apart conditions condition pulse-rate. As mediated general (aortic) they be assumed afferent impulses especially related probably originating some part apparatus under factor. Changes kneesdown much more regularly effective most subjects than knees-up. subjects, where effective, opposite have been found knees-down (acceleration) knees-up (slowing), while intermediate inclinations tend give rates. obviously their trunk. Slight repeated presumed impulses. Not only also blood-pressure adjustments influenced limbs. Static muscles large scale, knees bent described, soon remarkably rise systolic diastolic blood-pressures, comparable what strenuous exercise, differing respects mechanism its production. Marked times apart obvious disturbing causes, lability ordinarily apparently healthy persons. It remains seen whether study can information developing defects co-ordination control system, leading persistent high low pressures, abnormal levels established any differentiation types practicable. Part expenses inquiry defrayed grant Medical Research Council.