Refer to the Biochemistry in Focus section of your text for this chapter to answer this question.Adipocytes release uridine into the blood during fasting.Which hormone is found in the bloodstream under the same condition as uridine?glucagon, to increase blood glucose levelsinsulin, to decrease blood glucose levelsleptin, to decrease food intakecholecystokinin, to stimulate secretion of digestive enzymes from the pancreas

Uridine is an important pyrimidine nucleotide required for RNA synthesis in living organisms. It is produced by the de nova synthesis pathway in mammals. The liver is the organ that majorly regulates uridine biosynthesis. Apart from that uridine can also be produced by adipocytes. Glucagon is a hormone secreted by pancreas that controls the blood glucose level. It prevents the blood glucose from dropping very low and signals the liver cells to produce glucose from the stored glycogen. During fasting conditions, the liver cannot synthesize uridine, but it focuses on producing glucose from glycogen to balance the energy requirements. Insulin is a hormone that is also secreted by the pancreas and regulates the blood glucose level. Insulin dictates glucose metabolism and decides whether to utilize glucose to produce energy or to store it as glycogen in the liver when the glucose is present in excess. Under fasting conditions, the liver will break glycogen to produce glucose as an energy source, and hence insulin is not secreted under low glucose levels. Leptin is an enzyme that acts as an appetite suppressant and prevents the brain from initiating hunger responses. During fasting, the leptin levels decrease and provoke the hunger response to balance the energy requirements via food glucose. Cholecystokinin is an enzyme produced in the small intestine as part of the digestive process. When there are proteins and amino acids ingested as food, cholecystokinin is produced. It stimulates the gall bladder and pancreas to release bile juice and digestive enzymes respectively. Under fasting conditions, there is no intake of food. Hence cholecystokinin is not produced by the small intestine to break down proteins in food during fasting. Answer is A . During fasting, there won't be insulin to regulate glucose metabolism. There will be a decrease in leptin to create a hunger response, also there will not be any protein available in food intake that can be breakdown by cholecystokinin. Hence, Glucagon hormone regulates the glucose production from glycogen in liver, while the adipocytes can takeover the synthesize of uridine during the fasting conditions