After the oil and citric acid potion is ingested it is quickly transferred as chyme from the stomach, through the pyloric sphincter, to the duodenum as a series of spurts. The stomach plays only a minor role in the processing of the flush potion. Each spurt is about the volume of 1 teaspoon. The meal is unique being so oily and acid and there is nothing quite like it in such large quantities. The absence of a number of hormones fails to slow its transit into the duodenum. In the mucous walls of the duodenum the high acidity of the chyme stimulates the production of secretin and the fat stimulates the production cholecystokinin. Other hormones may also be secreted but secretin and cholecystokinin are dominant. These two hormones are highly complimentary and act as a catalyst on each other. Despite the gastric system wanting to slow down the digestive process it doesn't have a mechanism for dealing with the high acidity of the chyme. Normally hormones would send messages to the stomach to stop producing gastric acid but in the case of the potion it is already too acid enough for a meal consisting of only oil. The citric acid is not significance in terms of protein of carbohydrate so the meal is detected as being purely oil.
The two key hormones identified in the flush mechanism are cholecystokinin and secretin
Secretin has the following effects:
It stimulates the release of sodium bicarbonate from the pancreas. The pancreas is the primary organ responsible for neutralising acid chyme and produces sodium bicarbonate equal to several Alka-Seltzers every day. The high throughput of acid chyme in the duodenum produces a relative flood of bicarbonate which combines with the torrent of bile from the bile duct. The two streams meet at the sphincter of Oddi and pour into the duodenal chamber.
It stimulates the biliary duct cells to secrete bicarbonate and water, which expands the volume of bile and helps form a tidal wave of bile.
It enhances the effects of cholecystokinin which multiplies the demand for bile. Cholecystokinin is the primary hormone that signals the biliary system to supply bile.
It also reduces acid secretion from the stomach by inhibiting gastrin which is a hormone that stimulates secretion of gastric acid by the stomach. However the stomach content doesn't need the addition of gastric acid because the potion is acid enough. This attempt to slow down the transit of chyme to the duodenum if futile.
Forr completeness but of little significance to the flush; Secretin stimulates the secretion of bicarbonate from the duodenal Brunner's glands in order to assist neutralise the acidic chyme. Brunner's glands are located throughout the duodenum walls and their main function is to produce an alkaline secretion (containing bicarbonate) in order to:
Protect the duodenum from the acidic content of chyme
Provide an alkaline condition for the intestinal enzymes to be active
Lubricate the intestinal walls.
Cholecystokinin has the following effects:
It increase the production of hepatic bile secreted from the cells lining the bile ducts. This swells the volume of the bile and hence the flow of bile through the biliary system. This adds the effect of secretin which increases the flow of bicarbonate and water in the bile ducts.
It stimulates the contraction of the gallbladder and simultaneous relaxation of the Sphincter of Oddi resulting in the delivery of bile into the duodenum. This increases the pressure throughout the biliary system including the bile ducts in the liver which cases then to dilate (expand) slightly. The total increase in total volume is quite small about 70% the capacity of the gallbladder, about 45 mL in volume. The volume of liver bile ducts have been measured and estimated using computer scanning to be on average 24 mL. The bile ducts outside the liver, cystic and common bile ducts can vary in size and diameter considerably and are estimated a falling between the extremes of 2 and 50 ml. Consequently contraction of the gallbladder increase expands the bile ducts by between 75 and 150 percent.
It acts on the central nervous system causing nausea and anxiety, and weakly decreases the desire to eat. This may help to explain some of the emotional anomalies reported by individual post flushing.
Although not an important function in relation to the liver flush; it acts on the pancreas to stimulate the secretion of digestive enzymes, including trypsinogen, chymotrypsinogen (which are converted to trypsin and chymotrypsin in the duodenum), amylase, lipase, and maltase. Together these pancreatic digestive enzymes catalyse the digestion of some fats, protein, and carbohydrate.
Chyme continues to be delivered into the duodenum causing the biliary system and pancreas increase activity up to their maximum capability. The signals for more bile and more bicarbonate cannot be turned off until all the chyme is processed. Ultimately the biliary system has to find new levels of performance that are not seen by eating regular meals. The gallbladder contracts to its functional limits to maintain pressure in the biliary system and the bile ducts cells stream bicarbonate and water; the combined effect causes the bile ducts to expand and the bile gushes through a relaxed sphincter of Oddi where it meets the flood of pancreatic fluid. This provides the means for decongesting the liver of physical debris that has accumulated in the biliary system and to a lesser extent the pancreas.
The flush potion transits rapidly into the duodenum and it is estimated that 8 fluid ounces of the flush potion is processed in about 20 minutes. When no more chyme enters into the duodenum from the stomach, hormones levels fall back and the gallbladder relaxes to start a rapid refilling cycle and the whole biliary system goes into its basal (resting) state.
The combined effect of citric acid and oil in a fine emulsion and in such large quantities, its transfer to the duodenum at a high rate, causes an intense activity and mutual interaction of hormones that reinforce each other resulting in a tidal wave of biliary activity from the liver, gallbladder and pancreas. In summary the following condition are simultaneously created:
Contraction of the gallbladder resulting in:
positive pressure in the bile duct which causes:
expansion of the bile ducts
Increased flow of liver bile
Increased volumes of water and bicarbonate in the liver bile ducts
High demand for liver and gallbladder bile
Mutual interaction of hormones which magnifies demand
High demand for sodium bicarbonate from the pancreas