notes/education/nutrition/Digestive System.md

The primary roles of the digestive system are:

• breakdown of food into nutrients
• absorption of nutrients
• elimination of solid waste products Digestion is the process of breaking down large food molecules into nutrients that the body can use Absorption is the uptake and removal of nutrients from the digestive tract.
• The digestive tract is also called the gastrointestinal tract (GI), alimentary canal, or gut

The GI tract

Order

1. Mouth
2. Esophagus*
3. Stomach*
4. Small intestine (DJI)
   1. Duodenum
   2. Jejunum
   3. ileum*
5. Large intestine
6. Rectum
7. Anus

Sphincters

Sphincters are thickened regions of circular muscle that control the flow of contents at various points in the GI tract.

• Contracted:
  • Passageway closed
  • Flow is restricted
• Essential for normal digestion and absorption There are 3 main sphincters associated with digestion:

1. Gastroesophageal/lower esophageal/cardiac - connects the esophagus to the stomach
2. Pyloric - connects the stomach to the duodenum (small intestine)
3. ileocecal valve - Connects the small intestine to the large intestine The upper esophageal sphincter is at the top of the esophagus (not as important).

Digestion

Mechanical digestion refers to the physical treatment that food undergoes while it is in the intestinal tract

Chemical digestion refers to the breakdown of large molecules in food into smaller components, primarily by the action of enzymes.

• Enzymes are a protein that speeds up the rate of a chemical reaction without being altered in the process.
• Enzymes usually end in -ase and begin with the name of whatever they are working to digest:
  • Amylase digests amylose
  • Maltase digests maltose