The digestive organs in the abdomen work together to absorb nutrients and move food through the digestion process. They include the stomach, gallbladder, liver, pancreas, intestines, and urinary system.
The digestion process is interdependent and a problem with one organ may disrupt the function of another. For example, gallstones can block the bile duct, affecting liver function. They may also block the pancreatic duct, causing pancreatitis and severe illness.
This article examines each of the digestive organs in the abdomen, how they work together, and common health problems.
The digestive organs in the abdomen do not work alone. They depend on organs in the mouth and chest, such as the esophagus and tongue, to help chew, move food, and perform primary digestive functions.
The abdomen also includes the urinary system. The pelvis, the lower portion of the abdomen, contains reproductive structures.
Food travels to the stomach from the esophagus. Once it arrives, the stomach helps digest food via contractions and chemical enzymes.
The stomach has three layers: the oblique layer, the middle circular layer, and the external longitudinal layer, which breaks down food mechanically.
Acids such as hydrochloric acid further digest food into a liquid substance called chyme. A network of cells — including parietal cells, chief cells, G-cells, mucous neck cells, and D-cells — help chemically digest food by secreting stomach acids.
The stomach can also hold food until it moves further along the digestive tract.
The gallbladder is a small, pear-shaped organ next to the liver in the upper right abdomen. The liver forms bile, which helps digest fat and cholesterol and kill bacteria. The gallbladder stores this bile then releases it when the body needs it for digestion.
Bile drains into the gallbladder via the common hepatic duct, then drains into the cystic duct.
The gallbladder then releases bile through the common bile duct, passing through the pancreatic duct and eventually into the small intestine. A person can live without a gallbladder.
The liver is vital for a person to survive. It uses a group of lobes to help the body digest and store nutrients. It is a large organ in the upper right side of the abdomen, next to and under the ribs. It works closely with the pancreas and gallbladder.
One of its main functions is to make and release bile into the gallbladder. Bile also helps make some proteins that support blood clotting, filters toxins such as alcohol out of the blood, digests old red blood cells, stores glycogen, and stores some vitamins.
Another vital organ necessary for survival, the pancreas, is in the abdomen’s upper center to the right portion. It is long and narrow and works closely with the gallbladder and liver. An issue with either of these organs may affect the pancreas.
The pancreas also releases the hormone somatostatin. This maintains the body’s sugar-to-salt balance and vasoactive intestinal peptide, which helps control the secretion and absorption of water in the intestines.
Food travels from the stomach to the small intestine, where most of the nutrient absorption occurs. The small intestine uses enzymes from the liver and pancreas to aid nutrient absorption. Its various glands produce hormones and enzymes such as gastrin, secretin, and pro-glucagon to support digestion and absorption of various nutrients.
It is located in the middle to lower portion of the abdomen, below the stomach, and takes up a significant portion of the stomach. It contains three different portions:
- Duodenum: This processes liquid food from the stomach and digestive enzymes from the liver and pancreas.
- Jejunum: This portion performs most chemical digestion and nutritional absorption.
- Ileum: This opens to the ileocecal valve, which allows food to flow into the large intestine.
The large intestine is wider than the small intestine and rests at the lower portion of the stomach, extending down into the rectum and anus. Undigested food waste passes into the large intestine, becoming a bowel movement. The large intestine also absorbs some water and electrolytes, and its bacteria helps break down some nutrients, including vitamin K.
The large intestine includes the cecum, transverse colon, ascending colon, descending colon, and sigmoid colon. A small, finger-like projection from the large intestine, the appendix, can become infected, causing appendicitis.
Several organs in the abdomen form the digestive system, working together to absorb nutrients and eliminate waste.
The stomach is in the upper portion of the abdomen. Food travels here after moving down the esophagus. The liver, located on the left upper side of the abdomen, and the pancreas, located in the middle to the right side of the abdomen, release digestive enzymes that help digest food. The gallbladder, next to the liver, stores and releases bile.
Food moves to the small intestine from the stomach, which absorbs water and some nutrients. Digestive enzymes from the liver and pancreas travel to the small intestine to aid this process. Food moves to the large intestine and eventually to the anus and rectum, where people will have a bowel movement.
Portions of the urinary tract are also located in the abdomen. The kidneys, which reside near the middle of the abdomen toward the back, are bean-shaped organs that help filter and process waste.
From there, urine travels down the ureters and into the bladder, lying at the bottom of the abdomen, in the pelvis. The bladder holds urine until it travels out of the body through the urethra.
Some common problems of the digestive organs in the abdomen include:
- Appendicitis: Inflammation or infection in the appendix that, left untreated, may cause the appendix to rupture.
- Gallstones: These are stones in the gallbladder that break loose and travel to the surrounding ducts.If the gallstones move into another part of the digestive system, a person may experience complications.
- Heartburn: Stomach acid that travels back up the esophagus may cause a burning feeling in the chest.
- Constipation: This consists of slow, hard, or infrequent bowel movements.
- Abdominal pain: This may happen due to various reasons, such as digestive pain from gas, ulcers, gallstones, and irritable bowel syndrome.
The digestive organs of the abdomen are complex and interact with one another. If there is a problem with one organ, this may cause pain or dysfunction in another.
The abdomen is also home to a wide range of muscles that may cause pain and bones, such as the ribs, which can experience injuries.