In the intestines, the lumen is the opening inside the bowels and is surrounded by the other parts of the intestinal wall: the mucosa, the submucosa, the muscularis, and the serosa.

Since the mucosa is the innermost layer within the GI tract, it surrounds an open space known as the lumen.

mucosa

All segments of the GI tract are divided into four layers: the mucosa (epithelium, lamina propria, and muscular mucosae), the submucosa, the muscularis propria (inner circular muscle layer, intermuscular space, and outer longitudinal muscle layer), and the serosa (Figure 1).

The GI tract contains four layers: the innermost layer is the mucosa, underneath this is the submucosa, followed by the muscularis propria and finally, the outermost layer – the adventitia. The structure of these layers varies, in different regions of the digestive system, depending on their function.

The main organs that make up the digestive system (in order of their function) are the mouth, esophagus, stomach, small intestine, large intestine, rectum and anus. Helping them along the way are the pancreas, gall bladder and liver.

The liver (under the ribcage in the right upper part of the abdomen), the gallbladder (hidden just below the liver), and the pancreas (beneath the stomach) are not part of the alimentary canal, but these organs are essential to digestion.

duodenum

gallbladder

Bolus, food that has been chewed and mixed in the mouth with saliva. The term bolus applies to this mixture of food and solutions until they are passed into the stomach.

The following quick treatments can help induce a bowel movement in a few hours.

1. Take a fiber supplement.
2. Eat a serving of high-fiber food.
3. Drink a glass of water.
4. Take a laxative stimulant.
5. Take an osmotic.
6. Try a lubricant laxative.
7. Use a stool softener.
8. Try an enema.