Hormones and Appetite Control: Summary of Hormones, PDF

Hormones act on specific centers in the brain that affect the sensations of hunger and fullness, or satiety (Ahima & Antwi, 2008). Some individuals may have genetic abnormalities that lead to disruption in the cells being targeted by specific hormones. If a hormone is unable to function properly, th...

Hormones act on specific centers in the brain that affect the sensations of hunger and fullness, or satiety (Ahima & Antwi, 2008). Some individuals may have genetic abnormalities that lead to disruption in the cells being targeted by specific hormones. If a hormone is unable to function properly, the signal to stop eating may be diminished, leading to excessive weight gain (Austin & Marks, 2009). The control of appetite is closely regulated by specific hormones, including leptin, CCK, ghrelin, and PPY. A deficiency in hormone production or function can have a potentially detrimental impact on energy metabolism (Mullur, Liu, & Brent, 2014).\ \ Leptin is a hormone produced by adipose cells that decreases appetite when released. Leptin sends a signal to the brain signaling that enough food has been consumed and appetite should be inhibited. Leptin is supposed to tell the brain that we have reached a state of desired caloric intake and how many calories are stored (Klok, Jakobsdottir, & Dent 2007).\ Ghrelin is a hormone that is produced and released primarily by the stomach, with small amounts also released by the small intestine, pancreas, and brain. Ghrelin has the opposite effect of leptin, and thus is referred to as the hunger hormone because it stimulates appetite, increases food intake, and promotes fat storage. Ghrelin stimulates fat deposition and growth hormone release, leading to increased hunger and fat storage (Klok, Jakobsdottir, & Dent 2007).\ CCK (Cholecystokinin) is a hormone released in the gastrointestinal system and is responsible for stimulating the digestion of fat and protein (Sekiguchi, 2016). CCK is secreted by cells of the upper small intestine. CCK is released when amino acids or fatty acids enter into the stomach or beginning of the small intestines. CCK stimulates the gallbladder to contract and release stored bile into the intestine to help breakdown fat and protein.\ \ NPY (Neuropeptide Y) is a neuropeptide hormone linked to the autonomic nervous system. Neuropeptides are small protein-like molecules used by neurons to communicate with each other (Beck, 2006). Neuropeptide molecules influence the activity of the brain and the body in specific ways. NPY is a specialized hormone produced in a part of the brain called the hypothalamus. NPY helps stimulate the sympathetic nervous system, which stimulates appetite and fat storage (Beck, 2006).\ \ Insulin and Glucose\ Insulin is a hormone produced by the pancreas that is released when blood glucose levels are high, promoting the uptake of glucose for fuel or storage as glycogen. Insulin helps keeps blood-sugar levels from getting too high, also referred to as hyperglycemia. Insulin increases glucose uptake in peripheral tissue (e.g., skeletal muscle) while also decreasing the production of glucose by the liver.\ \ Glucagon is a hormone that is released when blood sugars decrease below a certain threshold. It stimulates the breakdown of stored glucose (glycogen) in the liver, releasing additional glucose into the bloodstream for fuel.