Digestion is the breaking down of large food particles into smaller ones while absorption is the movement of these smaller particles from the lumen of the digestive tract into the blood. Digestion begins in the mouth and is completed in the small intestine. Most absorption occurs in the small intestine while the primary function of the large intestine is the absorption of water.
The large S-shaped structure represents a longitudinal view of the mouth through the small intestine. The mouth begins at the upper left corner of the mind map. The first curve, where the structure is wider, is the stomach. The second curve and the remainder of the structure is the small intestine.
Just below the label 'Digestion Model' are two structures: the liver with its gallbladder and the scalloped pancreas. The ducts from these two organs fuse before entering the small intestine. The donut around the fused duct is the sphincter of Oddi.
The two squares in the upper left region of the map represent the central nervous system, CNS. The blunt-headed orange lines are nerves; solid lines are stimulatory nerves and dashed lines are inhibitory nerves.
The circle just above the mouth represents salivary glands. The circle just below the liver represents Brunner's glands.
Portions of the liver and pancreas are glandular in that they produce and secrete sodium bicarbonate, bile, and pancreatic juice.
Two small circles in the wall of the stomach represent single celled glands... chief cells and parietal cells.
All of the above exocrine structures can be further identified because each has a dashed line with a solid arrow head leading from it to its secretory product.
These are represented by four hexagons. Arrows leading from them point to their respective targets. A solid arrows means the target is stimulated by the hormone; a dashed arrow means the target is inhibited. When these arrows are located outside the symbolic GI tract it implies the hormones travel to their targets via the blood stream. One hormone (histamine) is local and does not enter the blood; its arrow is located inside the tract.
There are stretch receptors represented as small labeled squares, SR in the stomach and intestinal walls. There are also acid receptors, H+ in the wall of the small intestine (small square).
Last Updated: 7/19/2005