|MadSci Network: General Biology|
Thanks for your question! Before I answer your question, I would first like to review the major functions of the stomach, as well as its anatomy.
Functions of the stomach
The main functions of the stomach are to (1) store large quantities of food until they can be processed in the intestines; (2) mix ingested food with liquids secreted by the stomach (often called ‘gastric juices’), using a series of peristaltic muscle contractions, until it forms a semi-fluid mixture called chyme; and (3) empty food from the stomach into the small intestine in a slow, regulated manner to ensure proper digestion and absorption in the small intestine.
Anatomy of the stomach
The stomach is a C-shaped organ that lies toward the left side of the body. Anatomically, it can be divided into three main sections, beginning from top to bottom: (1) the fundus, (2) the corpus, or body, and (3) the antrum.
Hunger pangs: what are they and what do they mean?
When food is present in the stomach, peristaltic or wavelike, muscle contractions sweep through the walls of the stomach and help to mix food with gastric juices. However, another kind of intense muscle contraction, called hunger contractions, occur when the stomach has been empty for several hours. Hunger contractions are peristaltic contractions, mainly restricted to the body of the stomach. They can often be particularly strong, resulting in a contraction that lasts for two to three minutes! Hunger contractions are usually most intense in young people, who often have a higher degree of gastrointestinal "muscle tone" than older people. In addition, these contractions are increased by a low level of glucose in the blood, which usually occurs when an individual has not eaten for several hours.
When individuals have hunger contractions, they frequently experience pain in the pit of their stomachs. This pain, referred to as hunger pangs, usually does not begin until 12 to 24 hours after the last ingestion of food. In your question, you state that you experience hunger pangs even when you are not hungry. I can think of a few possible reasons for this. However, before I list some possibilities, I want to emphasize that my answer to the question you submitted to MadSci Network should not be used as a substitute for professional medical advice. If you feel that you have a health problem, you should seek professional medical assistance. One reason you may have ‘hunger pangs’ when you do not feel hungry is that perhaps you are hungry but you just do not feel that are. In this instance, you might think back to when you last ate, and the amount of food consumed at that time. Another possibility is that you are not experiencing hunger pangs, but rather pain of a different origin. Abdominal pain can result from a large number of things--hunger, stress, as well as a number of physiological disturbances. One way that physicians can narrow down these possibilities is by asking patients about the quality of the pain (for example, diffuse versus localized), and the specific location of pain in the abdomen.
I hope you find this information helpful. Should you have any further question, please do not hesitate to contact me. If you are interested in reading more, I suggest a general medical physiology text. For my answer, I referred to Textbook of Medical Physiology, ninth edition, by Arthur C. Guyton and John E. Hall.
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