Cards (9)

  • how is food kept in the stomach?
    food enters the stomach and is kept there by the contraction of 2 sphincters, or rings of muscles
  • what is the volume of the stomach?
    about 2dm3^3
  • how long does the food stay in the stomach?
    food may stay there for several hours
  • how does the food in the stomach mix with gastric juice?
    the stomach wall muscles contract rhythmically and mix the food with gastric juice secreted by glands in the stomach wall
  • where is gastric juice secreted from?
    its secreted from glands in depressions in the mucosa, called gastric pits
  • what does gastric juice contain?
    • peptidases, secreted by zymogen, or chief cells, at the base of the gastric pit - pepsinogen, an inactive enzyme, is secreted and activated by H+^+ions to pepsin, an endopeptidase which hydrolyses protein to polypeptides
    • hydrochloric acid, secreted by oxyntic cells - it lowers the pH of the stomach contents to about pH2, the optimum pH for the enzymes, and kills most bacteria in the food
    • mucus, secreted by goblet cells, at the top of the gastric pit - mucus forms a lining which protects the stomach wall from the enzymes and lubricates the food
  • what are the layers of the stomach wall?
    • mucosa (has large folds called rugae)
    • submucosa
    • circular muscle
    • oblique muscles (allow extra contractions)
    • longitudinal muscle
    • serosa
  • what is the pain caused when stomach contents move up into the oesophagus?
    the pain caused by the acids on the oesophagus wall is described as heartburn
  • what is this an image of?
    the structure of the gastric pit