2.4 Digestion
Completion requirements
Unit D
Module 6 ~ Lesson 2
Digestion Continues
Food enters the stomach through the esophageal sphincter. In the stomach, the food is mixed with gastric juices by peristalsis. The stomach secretes hydrochloric acid and the inactive form of pepsin called pepsinogen. The acid activates the enzyme which breaks proteins down into smaller peptides. The food exits the stomach through the pyloric sphincter into the small intestine.
The small intestine contains secretions from the pancreas, small intestine, and gall bladder. Bile, formed in the liver and secreted from the gall bladder, breaks larger globules of fat into smaller globules for digestion. It is not an enzyme, it just breaks up the large globules into smaller ones. Secretions from the pancreas contain bicarbonate, which neutralizes the stomach acid and increases the pH to about 8. Pancreatic secretion also contains trypsin, chymotrypsin, pancreatic amylase, and lipase for digestion of proteins, starch, and fats, respectively.
The small intestine contains secretions from the pancreas, small intestine, and gall bladder. Bile, formed in the liver and secreted from the gall bladder, breaks larger globules of fat into smaller globules for digestion. It is not an enzyme, it just breaks up the large globules into smaller ones. Secretions from the pancreas contain bicarbonate, which neutralizes the stomach acid and increases the pH to about 8. Pancreatic secretion also contains trypsin, chymotrypsin, pancreatic amylase, and lipase for digestion of proteins, starch, and fats, respectively.
Read
Read "Digesting and Absorbing Nutrients: The Small Intestine" on pages 222 to 230 of your textbook.
By OpenStax College [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
Nutrient Absorption
The resulting monosaccharides, amino acids, and disassembled triglycerides are small enough to be absorbed and transported to cells all over the body for use. The lining of the small intestine is covered with millions of finger-like projections called villi. The villi have a thin surface and contain a capillary and lymph vessel network, making them ideal for absorption of nutrients. The remaining undigested food continues on to the large intestine where large amounts of water are reabsorbed. The large intestine is also home to bacteria that break down remaining food and produce vitamins B-12 and K.
The Digestive System
Explore the digestive system by putting it into action in this activity.- Print off the Student Activity Sheet. If you don't have access to a printer, use the Word or Google document.
- Access the Digestive System Gizmo and follow the directions on the Student Activity Sheet.
- Do the Assessment Questions under the Gizmo and check your responses.