Anatomy & Physiology Gastrointestinal #19
Which is the primary organ of the gastrointestinal (GI) tract that is involved in the absorption phase of the digestive process?
The rectum, at its point of origin, connects to the descending colon while its terminal end is the last structure of the GI tract. It is not involved in the absorption phase of the digestive process; instead, it allows the excretion of stool, a waste product of the digestive process.
While some absorption of nutrients (e.g., water soluble vitamins and medications) can occur in the stomach, it is not the primary organ in the absorption phase of the digestive process.
- Small intestine
The small intestine is the primary organ of the absorption phase of the digestive process. Approximately 90% of the digestion and absorption of food occurs in the small intestine.
- Large intestine
The large intestine has two functions. One of these functions is the absorption of water; however, the primary function of the large intestine is removing the by-products (i.e., waste) of the digestive process to the rectum for removal from the body.
Absorption is the process that occurs during the digestive process. During absorption, chemical digestion breaks chyme down into simple molecules that pass through the cell membranes of the stomach or small intestine’s lining into the blood or lymph capillaries for distribution throughout the body.
While some absorption of nutrients occurs in the stomach, the primary organ in the absorption phase of the digestive process occurs in the small intestine. Chyme, which is produced from fluid and foods that are partially digested within the stomach, is primarily absorbed in the small intestine as usable minerals and nutrients. Minerals and nutrients are necessary to sustain optimal nutritional status and thereby life itself.
Test Taking Tip
Consider the function of each GI structure to determine the correct choice for this question.