Spectral Analysis Of Heart Rate Variability And Blood Pressure Variability Under Gravitational Stress

Gravity is the most constant of the various environmental conditions that influenced human evolution. Thus, the structure and function of human cardiovascular system have been finely tuned to Earth's gravitational field. The circulatory system must be capable of delivering blood to the various body parts and of bringing it back from the extremities against the force of gravity. To accomplish this, specific force of contraction of the heart, appropriate elasticity of the arterial blood vessel walls, and a system of one-way valves in the venous system are among the specializations required to counteract the tendency of blood to pool in dependent body parts. Additionally, arterial baroreflex and other feedback control mechanisms are developed for the rapid adjustment to a drop in arterial blood pressure above the heart level when a person moved from supine to standing posture ensuring a sufficient blood flow to the brain. However, as compared with...