Vattenhallen Science Center

The glands located in the gastric mucosa produce 2–3 litres of gastric juice per day. Gastric juice contains hydrochloric acid that helps break down food and kill bacteria that could potentially make us ill. The stomach is an incredibly acidic place – it has a pH level of approximately 1.5 – yet the stomach does not corrode, thanks to the mucous lining located inside the stomach to protect it.

However, occasionally there is damage to the stomach that creates an ulcer. We now know that the most common cause of a stomach ulcer is a special kind of bacteria – helicobacter pylori – one of the few bacteria that can survive in such an acidic environment as the stomach. If treated with antibiotics, the ulcer heals within a few weeks. Too much of certain types of painkillers can also damage the lining of the stomach, so it’s better to think about why you, for instance, have a headache and if you can solve the problem with water, food or rest! 

Listen! - place your ear against someone else’s belly, and you’ll probably hear the sounds of the stomach or the intestines. If the person then drinks some water, perhaps you can hear the sound of the water travelling down into the stomach! 

The stomach is located much higher up in the body than you might think. It starts just below the left nipple and ends slightly below your right rib cage. Here, the food is kneaded together with gastric juices for several hours to make it as loose as baby formula, allowing it to be pushed out into the small intestine. This all happens automatically, without any conscious effort on your part. Once the stomach is empty, it may start to rumble. However, you might think you are hearing your belly rumbling, but in fact it is usually the sound of your intestines moving and signalling that they want more food to work with! 

The stomach looks like an oblong bag, which can hold roughly 1.5 litres of food and liquids. It has two openings – the upper and the lower oesophageal sphincters – connecting the stomach to the oesophagus and the small intestine. When the stomach is empty, it is creased, and as it fills, the creases are evened out. In the grooves there are glands that produce gastric juice, which is needed to break down food. 

The “brains” behind the activities in our stomach and intestines is the enteric nervous system. This complex system is located in the organ walls themselves, between the muscles and the lining of the gastrointestinal tract, and is needed to enable the body to control, at all times, what happens to the food we eat, to make sure that all the cells in the body always have the energy and nutrients they need. The enteric nervous system is able to send signals directly to the brain. This is also why you, for example can experience headache and nausea when you are hungry or thirsty. 

Sometimes you get a stomach ache – although the actual discomfort usually comes from the intestines. The pain can be caused by many different things, for example stress and anxiety. Stomach ache can also be caused by bacteria which have infected you with disease, or from eating something that the body has a hard time breaking down, resulting in gas inside the intestines. If you suddenly experience severe pain in the stomach, this could also be an indication of appendicitis, which you can read more about when you get to the large intestine.