The blood sugar level rises gradually to a peak during the first two hours and then falls during the third and fourth hours to the previous fasting level. All blood sugar values lie well above the 80 mg. baseline. In the fasting state glycogen is constantly being broken down in the liver cells into a simpler chemical called glucose or sugar which is then liberated into the blood stream at such a rate as to maintain the blood glucose level at around 80 mg. per 100 cc. This breakdown of liver glycogen is controlled chiefly by nerves of the autonomic system which consists of two divisions, the sympathetic and the parasympathetic. Note the sharp rise to 150 mg.
Hatched area indicates the extent and duration of the low blood sugar period.
Note sharp rise to around 250 mg. Individuals with this type of curve have symptoms resembling those seen in hypoglycemia and may also be susceptible to polio. In general, the action of the sympathetic division is to facilitate and hasten the breakdown of liver glycogen with subsequent elevation of the blood sugar level, and the action of the parasympathetic division is to favor the synthesis and storage of liver glycogen. The two divisions are thus essentially antagonistic, and, at any moment, the blood sugar level will be the resultant of these two opposing forces. As for the endocrine glands, the important ones in blood sugar regulation are the pancreas and the adrenals, both of which are under the control of the pituitary gland.