Structure and function of the stomach, pancreas, gall bladder, duodenum, ileum and colon

Structure and Function of the Stomach

The stomach is a large, muscular organ located in the upper left part of the abdominal cavity. It has a sac-like shape and is directly connected to the esophagus at the cardiac orifice.
Within its structure, the stomach wall is composed of three layers of muscles. These muscles aid in the physical breakdown of food through the process of peristalsis.
Its main function is to break down food particles into a liquid mixture known as chyme. It achieves this through the secretion of gastric juice which contains hydrochloric acid and digestive enzymes.

Structure and Function of the Pancreas

The pancreas is a glandular organ located behind the stomach. It has both an exocrine and an endocrine function.
This organ produces and releases pancreatic juice into the duodenum (the first part of the small intestine). This juice contains enzymes such as amylase, protease and lipase which aid in the digestion of carbohydrates, proteins and fats respectively.
The endocrine function includes the release of insulin and glucagon hormones which helps to regulate blood sugar levels.

Structure and Function of the Gall Bladder

The gall bladder is a small organ tucked beneath the liver on the right side of the abdomen. It has a pear-like shape and can hold up to 50 ml of fluid at full capacity.
Gall bladder’s main function is to store the bile produced by the liver. Bile is crucial for the digestion and absorption of fats.
When fatty food is ingested, the gall bladder ejects bile into the duodenum to aid in digestion.

Structure and Function of the Duodenum

The duodenum is the first section of the small intestine, forming a C-shaped arc attached to the stomach.
It receives semi-digested food, or chyme, from the stomach and also receives bile from the gall bladder and digestive juices from the pancreas.
The main function of the duodenum is to continue the process of digestion started in the stomach, through the action of enzymes and bile.

Structure and Function of the Ileum

The ileum is the final and longest segment of the small intestine. It is coiled in the lower part of the abdomen, and it links the small intestine to the colon.
The main function of the ileum is to absorb nutrients from the digested food. The wall is lined with numerous villi and microvilli to increase surface area for maximum nutrient absorption.
It also absorbs vitamin B12 and bile acids that will be recycled back to the liver.

Structure and Function of the Colon

The colon, also known as the large intestine, is a long tube-like structure. It begins at the cecum and ends at the rectum.
Its primary functions are to absorb water and salts from the remaining indigestible food matter, and to store and remove waste.
The colon is also home to numerous bacteria and yeasts, collectively referred to as gut flora, that aids in the breaking down of food residues through fermentation.