BIO 203 Lecture Notes - Lecture 23: Exocytosis, Ileum, Portal Vein
18 Aug 2018
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Document Summary
Conducts bolus of food to stomach by creating pressure gradients. Involuntary waves of contractions move food bolus to stomach: peristalsis. Salivary amylase continues to digest starch and glycogen. Animals do not need to eat constantly with food. Limit of stomach contains thousands of gastric pits; each contains several cell types. Digests proteins by breaking peptide to pepsin bonds. The acid conditions of the stomach (ph approximately 2) Disrupts the extracellular matrix that binds cells together. Created more surface area on food particles, more interactions b/w enzymes and substrates. Mixture of pepsin and acid in stomach. Acid denatures the proteins exposing peptide bonds to pepsin. Pepsin is one of the few enzymes that is most effective at low ph. Reflux of gastric juice into the esophagus can cause a variety of disorders. Keeping acidic stuff in stomach is important. Mucus coats and protects the stomach epithelial cells from acid and microbes.
