digestion

Definition

Target type: biologicalprocess

The whole of the physical, chemical, and biochemical processes carried out by multicellular organisms to break down ingested nutrients into components that may be easily absorbed and directed into metabolism. [GOC:isa_complete, ISBN:0198506732]

Digestion is a complex process that breaks down food into smaller molecules that can be absorbed by the body. It begins in the mouth, where food is mechanically broken down by chewing and mixed with saliva. Saliva contains enzymes, such as salivary amylase, that start the chemical breakdown of carbohydrates.

The food bolus then travels down the esophagus to the stomach. The stomach churns the food and mixes it with gastric juices containing hydrochloric acid and pepsin, an enzyme that breaks down proteins. The stomach also produces intrinsic factor, which is essential for the absorption of vitamin B12.

From the stomach, partially digested food enters the small intestine, where the majority of digestion and absorption takes place. The small intestine receives digestive enzymes from the pancreas and bile from the liver. Pancreatic enzymes, such as pancreatic amylase, lipase, and protease, further break down carbohydrates, fats, and proteins, respectively. Bile, produced by the liver and stored in the gallbladder, emulsifies fats, breaking them down into smaller droplets that are easier to digest.

The small intestine is lined with finger-like projections called villi, which increase the surface area for absorption. Nutrients are absorbed through the villi and enter the bloodstream, where they are transported to the body's cells.

Any undigested food residue passes into the large intestine, or colon. The colon absorbs water and electrolytes, and bacteria in the colon ferment any remaining undigested carbohydrates. The final product of digestion is feces, which is eliminated from the body through the rectum and anus.

Digestion is a coordinated process that involves multiple organs and systems. It is essential for providing the body with the nutrients it needs to function properly.'
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Proteins (14)

Compounds (201)