Effect of Age on Sympathetic Nervous System

The sympathetic nervous system is responsible for up and down regulating many homeostatic mechanisms in living organisms like blood pressure control, urinary bladder control, control of heart rate etc. Fibers from the SNS innervate tissues in almost every organ system, providing at least some regulatory function to things as diverse as pupil diameter, gut motility, and urinary output. In most places it works complementary to parasympathetic nervous system e.g. in heart. In some places sympathetic system is the only component of ANS which control the function e.g. blood vessels. It is perhaps best known for mediating the neuronal and hormonal stress response commonly known as the fight-or-flight response. This response is also known as sympatho-adrenal response of the body, as the preganglionic sympathetic fibers that end in the adrenal medulla (but also all other sympathetic fibers) secrete acetylcholine, which activates the great secretion of adrenaline (epinephrine) and to a lesser extent noradrenaline (norepinephrine) from it. Therefore, this response that acts primarily on the cardiovascular system is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly via catecholamines secreted from the adrenal medulla.

Ageing is a natural process, everyone in the world has to face problems associated with increasing age. As with advancing age the capacity of every system of human body declines. The capacity of sympathetic nervous system i.e. capacity of fight or flight response also declines. In other words with increasing age capacity of a person to face stress decreases, which leads to increased susceptibility for cardiovascular events like MI, stroke etc. Thus it seems logical to study the pattern of change in sympathetic status through ages.