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.
  A Covalent (or molecular) bond is a bond between two non-metallic elements. This means that they share electrons inside the molecules. OR A type of chemical bond in which there is mutual sharing of electrons between two atoms is called covalent bond. covalent bond is a bond between two non-metallic elements. This means that they share electrons inside the molecules. OR A type of chemical bond in which there is mutual sha â¦ ring of electrons between two atoms is called covalent bond.