Activities in the Stomach

• Food breakdown, gastric juice is regulated by nerves and hormones
• Presence of food or rising pH causes the release of the hormone gastrin
• Gastrin causes stomach glands to produce:

  -protein-digesting enzymes

  -mucus

  -hydrochloric acid
• Hydrochloric acid makes the stomach contents very acidic
• Acidic pH:

  -activates pepsin for protein digestion

  -provides a hostile environment for microorganisms
• Protein-digestion enzymes:

  -pepsin: an active protein-digesting enzyme

  -rennin: works on digesting milk protein in infants
• Alcohol and aspirin are virtually the only items absorbed in the stomach
• hydrochloric acid


  kills bacteria in stomach and gives an acidic environment for enzymes to work
• pepsin


  an enzyme that converts protein into amino acids
• lipase


  an enzyme that converts fats (lipids) into fatty acids and glycerol