Nerve fibres of the parasympathetic nervous system arise from the central nervous system. Specific nerves include several cranial nerves, specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve. Three spinal nerves in the sacrum (S2-4) also act as parasympathetic nerves.
The word longevity is sometimes used as a synonym for life expectancy in demography - however, the term longevity is sometimes meant to refer only to especially long-lived members of a population, whereas life expectancy is always defined statistically as the average number of years remaining at a given age.
Bond ladders are a form of asset-liability matching. Bond ladders can work well for retirement cash flow needs. To build a bond ladder, you purchase bonds (individual bonds not bond funds) in your account so that the maturity dates of the bonds are staggered, or laddered, across a specified period of time. Sometimes this is called asset-liability matching, meaning you have an expense coming up (such as a year's worth of retirement spending) so you buy an asset (a bond) that will be available to meet that expense when it occurs.