The parasympathetic nervous system activates the relaxation, or rest-and-digest, response. Roughly the opposite of the fight-or-flight response of the sympathetic nervous system, the relaxation response involves restoration of energy reserves and other peace time functions, such as repair and reproduction.
On this day in 1953, Cambridge University scientists James D. Watson and Frances H.C. Crick announce that they have determined the double-helix structure of DNA, the molecule containing human genes.hough DNAâshort for deoxyribonucleic acidâwas discovered in 1869, its crucial role in determining genetic inheritance wasnât demonstrated until 1943. In the early 1950s, Watson and Crick were only two of many scientists working on figuring out the structure of DNA.
The history of the discovery of the structure of DNA is a classic example of the elements of the scientific method: in 1950 it was known that genetic inheritance had a mathematical description, starting with the studies of Gregor Mendel, and that DNA contained genetic information (Oswald Avery's transforming principle).