Stomach

• What features does the internal structure of the stomach have?

  -rugae: folds in the stomach wall that allow it to stretch and expand after eating

  -circular and longitudinal muscles

  -oblique muscles provide stronger contractions
• What is the function of the stomach?

  Churns food (physical/mechanical digestion) to mix it with gastric juice
• What are gastric glands?

  Pits in the mucosa
• What types of cells are found in the gastric glands?

  -goblet cells

  -oxyntic cells

  -chief cells
• What is the function of goblet cells?

  Secretes mucus for lubrication and prevents autodigestion
• What is the function of oxyntic cells?

  Secretes HCl: this lowers the pH to provide the optimum pH for pepsin, kills pathogens and activates pepsinogen
• What is the function of chief cells?

  Secretes pepsinogen (an inactive precursor of pepsin): this prevents autodigestion of the gastric gland.
• How is pepsinogen activated?

  By hydrogen ions (H+) from HCl produced by oxyntic cells in the gastric glands
• What is the function of endopeptidases?

  they hydrolyse peptide bonds inside the polypeptide chain to produce shorter peptides, e.g. pepsin
• What is the function of exopeptidases?

  They hydrolyse peptide bonds at the ends of polypeptide chains to produce single amino acids.
• What are the different types of exopeptidases?

  Aminopeptidase and carboxypeptidase
• Proteins are digested fastest when you have a mixture of endo and exopeptidases, because the endopeptidases produce more ends for the exopeptidases to work on
• What is chyme?

  Partly digested food and gastric juice that leaves the stomach