chapter 24 lecture 11 is on regulation and aging there are three phases in gastric secretion and Mobility the cephalic phase the gastric phase and the intestinal phase during the cephalic phase dots of food are going to stimulate it as well as receptors for the site of food for the smell of food and for the taste of food during the gastric phase the stretch receptors are going to detect that there's been something in your stomach because they're going to have distension and chemo receptors are going to detect that the pH of the gastric juices increased during the intestinal phase stretch receptors detect extension of the duodenum and chemoreceptors are also going to detect fatty acids and glucose when food moves into the stomach and it starts producing acid when the acid levels have been detected to decrease the way it does it in a parietal cell as it takes water and carbon dioxide and mixed by car makes carbonic acid from them and then bicarbonate and hydrogen ions the hydrogen ions then leave through the um parietal cell using a potassium symporter or antiporter and the leftover bicarbonate then diffuses into the blood capillaries nearby because of this we have what's called an alkaline tide after a meal because all the bicarbonate that's produced the pH of your blood from the area of your stomach is going to increase going to become more alkaline that alkalinity then is used by the pancreas the increase bicarbonate is used by the pancreas to make pancreatic juice encephalic phase we have sensory receptors in the head and it's going to prepare the mouth and the food for the mouth and stomach for the food that's about to be eaten so in the cortex we have this since the sight smell taste and thought and they're all going to stimulate the parasympathetic nervous system the salivary glands are also going to be stimulated by the facial nerves and the glossopharyngeal nerves and vagus nerve stimulation is going to increase stomach muscle and glandular activity In the gastric phase the nervous control keeps the stomach active so it's getting the information from the stretch receptors and the chemoreceptors you're going to have vigorous peristalsis that churning and glandular secretions and then the Communist released into the duodenum the endocrine influences over the stomach activity come because the distension also things like caffeine and protein cause an increase of gastrin to be secreted into your bloodstream which leads to an increase in the gland glandular secretion from the stomach including acid and gastrin also is going to increase churning and it's going to relax the pyloric sphincter during the intestinal phase food enters the small intestine and there again we have stretch receptors but there are also going to be receptors that are going to detect fatty acids and sugar to regulate the types of secretions that are going to be released the sympathetic nervous system when it acts is going to slow the stomach activity and increase intestinal activity The enterogastric Reflex inhibits gastric motility increases contraction pyloric sphincter and decreases gastric emptying hormonal influences here we have secretin cholecystokinin and gastric inhibitory peptide secretin stimulates flow of pancreatic juice that has bicarbonate in it to neutralize the acid from the stomach and also inhibits the secretion of the gastric juice cholecystokinin decreases stomach emptying stimulates secretion of pancreatic juice that has enzymes for fats and lipids and it for lipids and carbohydrates and it increases the flow of bile gastric inhibitory peptide decreases stomach secretions decreases stomach motility as well as emptying stomach certain things are going to be absorbed water electrolytes some drugs like aspirin alcohol although most alcohol is absorbed in the small intestine to absorb alcohol in the stomach if you have um fat in your stomach it's going to slow the passage of alcohol into the intestine and the gastric mucosal cells have the out that alcohol dehydrogenase we talked about before which converts some of the alcohol to acetylaldehyde um women have less of this than men do's and they also have less total body fluid so a woman and a man drinking the same amount of alcohol the woman will have a higher blood alcohol level the regulation of chyme release is controlled by both neural and hormonal reflexes so here we have distension of the stomach proteins are going to be partially broken down and maybe alcohol or caffeine in the stomach this increases secretion of gastrin and we also have increased a generation of vagus nerve signaling contraction of lower esophageal sphincter you have increased stomach motility and relaxation of the pyloric valve that stimulates gastric emptying when you have fatty acids glucose and partially digested proteins in the duodenum we want to slow down what's being released from the stomach so that that can those substances can be worked on in the small intestine so we have an increase in cholecystokinin the enterogastric reflex is going to be initiated the stomach is going to be less motile and gastric density is going to be inhibited the endogastric reflex is going to regulate the amount of the amount of time that's released into the intestines there's going to be sensory impulses sent in the Doula to inhibit parasympathetic stimulation in the stomach but increase secretion of cholecystokinin as well as sympathetic impulses and this inhibits gastric emptying excuse me vomiting is also called emesis and it's the forceful expulsion the contents of mouth and duodenum through the mouth of the stomach and thwad them through the mouth cause can be many things sometimes just seeing someone else vomit can make a person vomit so unpleasant sites general anesthesia is a big one which is why they generally don't want you to eat or drink anything after midnight the night before your surgery dizziness can make you vomit certain drugs can make you vomit or just irritation distension of the stomach the medulla is where the vomiting reflex is controlled and it causes stomach contraction and relaxation in the sphincter so the the contents of the stomach are squeezed but between the abdominal muscles and the diaphragm and force through the mouth if you vomit a lot it can cause fluid loss as well as a condition called alkalosis which has to do with a vast decrease in the amount of gastric juice in the stomach as we get older we have decreased secretions decreased motility so there would be an increase in things like um constipation which would self-cause problems with things like hemorrhoids developing diverticuli things like that loss of strength and toned muscle tissue making it even harder to pass feces change in the feedback mechanisms and diminished response to pain as well as internal stimuli some things that become more common as we age sores throughout the GI tract periodontal disease a decrease in ability to taste difficulty swallowing an increase in hernias gastritis ulcers malabsorption jaundice cirrhosis pancreatitis hemorrhoids and constipation cancer the colon becomes more common as we get older so usually once a person hits 50 they have to have a colonoscopy every few years to look for polyps goals for this election describe three phases of digestion Define enterogastric reflex in the emesis and list the changes in the GI tract that happen due to aging