The Physics Factbook™
Edited by Glenn Elert -- Written by his students
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|Curtis, Helena & N. Sue Barnes. Invitation to Biology. 5th Edition. New York: Worth, 1994: 529.||"The human stomach, distended, holds 2 to 4 liters of food."||2–4 L|
|Radcliffe, Donald V. Stomach. Compton's Encyclopeadia Online v3.0. The Learning Company, 1998.||"The stomach of an adult is about 10 inches (25 centimeters) long and can easily expand to hold as much as l quart (0.9 liter) of food."||0.9 L|
|Wenzel, V. et al. Respiratory system compliance decreases after cardiopulmonary resuscitation and stomach inflation: impact of large and small tidal volumes on calculated peak airway pressure. [Medline Abstract] Resuscitation. 38 (August 1998): 113-118.||"Respiratory system compliance was measured at prearrest, after ROSC, and after 2 and 4 l of stomach inflation in the postresuscitation phase; peak airway pressure was subsequently calculated."||2–4 L|
|Bevan, Dr. James. Handbook of Anatomy and Physiology. New York: Simon & Schuster, 1978: 45.||"The stomach is a muscular sac that can contain about 1.5 litres of fluid."||1.5 L|
|Johnson, George B. Holt Biology: Visualizing Life. Orlando: Holt, Rinehart & Winston, 1994: 769.||"The stomach can expand to hold up to 4 L (4.2 qts.) of food, more than 50 times its empty volume."||4 L
Do you remember the last time you said "Ahhhh, I'm too full to take another bite." Many of us will probably stop eating, while others may continue stuffing themselves because it is a buffet and they want to get their money's worth. The ones who stop eating might think that the ones who continue are crazy. How can one's stomach fit so much food? The stomach has a lot of functions and one these is to expand and contract.
This J-shaped organ has very active muscles. These muscles expand and contract depending on how much food is in the stomach. This contraction is a form of mechanical breakdown of the food. The purpose of this breakdown is to increase the available surface area for the chemicals to act on it. The gastric glands of the stomach secrete enzymes that perform chemical breakdown, partly digesting the proteins. Pepsin is the enzyme that breakdown protein. The gastric gland also secretes hydrochloric acid that kills almost all the bacteria in the food. It also secretes mucus that protects the stomach wall from the hydrochloric acid. By the time all the food is mechanically and chemically broken down, the food becomes a semi-fluid substance that leaves the stomach by peristalsis entering the small intestine.
The structure of the stomach is quite unique. It can be divided into four subdivisions: the cardia, the fundus, the body, and the pylorus. The cardia is the region that is closest to the heart and is where the esophagus is connected to the stomach. The fundus is the region that curves above the rest of the stomach (with respects to a person who is standing upward). The body of the stomach is the largest region located in the center. The pylorus is the region that is connected to the small intestine. The cardia and the pylorus have sphincter muscles that regulate the movement of food and fluids. You don't want the hydrochloric acid to back up into your esophagus. When you vomit and have a burning sensation in your esophagus, it's the hydrochloric acid from the stomach that causes it.
The volume of the human stomach varies depending on the person. Generally, human stomachs have a volume about one liter, which is a little more than one quart. Since the stomach has the ability to expand, it can hold much more food. The human stomach can be distended up to four liters, which is more than one gallon. Imagine your stomach to be an empty one-gallon milk carton. There is plenty room for food! So the next time you go out to an "all you can eat" restaurant, remember that there is actually more room that you think that is available in your stomach. But honestly, stuffing oneself to the limit is not very safe or healthy. Don't abuse your stomach because you will need it for quite a long time.
Jonathan Cheng -- 2000
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