BIO 241 1st Edition Lecture 20 Outline of Last Lecture I Esophagus II Stomach gross anatomy III Stomach histology IV Mechanical digestion in the stomach V Chemical digestion in the stomach Outline of Current Lecture II Stomach regulation cephalic phase III Stomach regulation gastric phase IV Stomach regulation intestinal phase V Negative feedback of gastric phase VI Gastric emptying VII Digestion and absorption in stomach VIII Accessory organs pancreas IX Pancreatic juice X Pancreatic regulation Current Lecture II Gastric regulation is controlled by three phases cephalic gastric and intestinal The cephalic phase is initiated by psychic stimuli like the thought anticipation sight taste smell and sound of food This triggers parasympathetic output via the tragus nerve cranial nerve X which stimulates the stomach s enteric nervous system This increases gastric secretion and motility III The gastric phase is initiated by food entering the stomach Its regulation is shown below These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV The intestinal phase begins when chyme enters the duodenum It is shown below V The second phase gastric has a negative feedback loop that is shown below VI Gastric emptying rates depend on whether the stomach is being stimulated or inhibited Its regulation is shown below VII The GI tract has now accomplished several things dealing with digestion Starch is converted to maltose by salivary amylase breaks down starch in the mouth This action stops in the stomach Proteins are converted to partially digested proteins through the action of pepsin Lipids are converted to partially digested fats through the action of lingual and gastric lipase Chyme is then created from food drink saliva and gastric juice There is no significant amount of absorption by the stomach mucosa Water electrolytes aspirin and some lipid soluble drugs are absorbed VIII The pancreas lies posterior to the greater curvature of the stomach The pancreas consists of the main pancreatic duct hepatopancreatic ampulla of Vater accessory pancreatic duct and the hepatopancreatic sphincter of Oddi shown below It is 99 exocrine and 1 endocrine IX Pancreatic juice consists of sodium bicarbonate NaHCO3 pancreatic amylase pancreatic lipase cholesterol esterase nucleases DNAse and RNAse and protein digesting enzymes trypsinogen chymotrypsinogen and procarboxypeptidase These last three are secreted in the inactive form and are activated in the small intestine by the enterokinase Pancreatic lipase and cholesterol esterase are fat digesting enzymes X The regulation of the pancreas is shown below
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