Which nutrients yield the most energy?

A. Listeriosis is a bacterial infection caused by Listeria monocytogenes, typically from contaminated food, and is particularly dangerous during pregnancy. It is unrelated to cravings for nonfood items.

B. Famine refers to a widespread scarcity of food, often due to crop failure or disaster. It is not a medical condition involving cravings.

C. Preeclampsia is a pregnancy-related condition characterized by high blood pressure and protein in the urine, sometimes accompanied by swelling. It does not involve cravings for nonfood substances.

D. Pica is the medical term for a craving and consumption of nonfood substances such as dirt, clay, chalk, ice, or paper. It is often associated with nutritional deficiencies (e.g., iron or zinc deficiency), pregnancy, or certain mental health conditions. Pica can lead to health risks, including gastrointestinal blockages, poisoning, or infections if the nonfood items are contaminated.

A. Amylase is an enzyme, not a hormone. It aids in carbohydrate digestion by breaking down starch into sugars but does not regulate blood glucose levels.

B. Leptin and ghrelin are hormones involved in appetite regulation. Leptin signals satiety, while ghrelin stimulates hunger. They influence energy intake but do not directly control blood glucose.

C. Glucagon does help raise blood glucose, but cholecystokinin (CCK) primarily regulates digestion by stimulating bile and pancreatic enzyme release and signaling satiety; it does not directly control glucose levels.

D. Insulin and glucagon are the primary hormones responsible for maintaining blood glucose homeostasis. Insulin, secreted by pancreatic beta cells, lowers blood glucose by promoting glucose uptake into cells and storage as glycogen in the liver and muscles. Glucagon, secreted by pancreatic alpha cells, raises blood glucose by stimulating glycogen breakdown (glycogenolysis) and glucose production (gluconeogenesis) in the liver. Together, they maintain blood glucose within a narrow, healthy range, essential for energy supply to the brain and other tissues.