Its action is described as being complementary to that of the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response. 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.
A healthy BMI is considered to be between 18.5 and 24.9. Based on these BMI tables, the National Heart, Lung and Blood Institute suggests that a healthy weight range for women who are 5 feet 4 inches tall is 110 to 140 pounds.
The average adult male and female in the United States has a BMI of around 26.5, according to the National Health and Nutrition Survey. A BMI of 18.4 to 24.9 is considered healthy, while 25 to 29.9 is described as overweight. A BMI of 30 or above falls in the obese category. The average American having a BMI of 26.5 is overweight and needs to implement dietary changes and exercise to drop down to a healthy weight range.