BIO 203 Lecture Notes - Lecture 21: Pylorus, Common Bile Duct, Gastric Pits
14 Dec 2016
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Document Summary
Conducts bolus of food to stomach by creating pressure gradients. In human: striated muscle at top of esophagus. Under voluntary control: smooth muscle in lower esophagus. Involuntary waves of contractions move food bolus to stomach: peristalsis. Salivary amylase continues to digest starch and glycogen. Storage- a large elastic organs: animals do not need to eat constantly, small intestine not overwhelmed with food. Peristaltic contraction for movement and segmental contraction for mixing the food together. Lining of stomach contains thousands of gastric pits; each contains several cell types. Disrupts the extracellular matrix that binds cells together. Creates more surface area on food particles more interactions between enzymes and substrates. Converted to active form after release: activated only where needed. Mixture of pepsin and acid in stomach. Effective at digesting proteins because: acid denatures the proteins exposing peptide bonds to pepsin, pepsin is one of the few enzymes that is most effective at low ph.
