question: How does your stomach know the difference between food/liquid - bowels/bladder?
comment: Simply, it doesn't. Solid food is broken down in your intestines and eventually expelled from your bowel. On the way, blood vessels extract moisture from your bowel contents by osmosis. Your kidneys filter your blood, and extract excess minerals and water, which are excreted from your bladder in the form of urine.
passages: Section::::Regulation.
  
  The digestive system has a complex system of motility and secretion regulation which is vital for proper function. This task is accomplished via a system of long reflexes from the central nervous system (CNS), short reflexes from the enteric nervous system (ENS) and reflexes from GI peptides working in harmony with each other.
  
  Section::::Regulation.:Long reflexes.
   The largest component of secreted fluids is ions and water, which are first secreted and then reabsorbed along the tract. The ions secreted primarily consist of H, K, Cl, HCO and Na. Water follows the movement of these ions. The GI tract accomplishes this ion pumping using a system of proteins that are capable of active transport, facilitated diffusion and open channel ion movement. The arrangement of these proteins on the apical and basolateral sides of the epithelium determines the net movement of ions and water in the tract.
   The secretion of gastrointestinal enzymes, such as gastrin and secretin, is regulated through cholinergic neurons residing in the walls of the digestive tract. Hormone secretion is controlled by the vagovagal reflex, where the neurons in the digestive tract communicate through both afferent and efferent pathways with the vagus nerve.
  
  Section::::Anatomy.
  
  Section::::Anatomy.:Enteric nervous system.
   Section::::Regulation.:Short reflexes.
   Food then moves on to the jejunum. This is the most nutrient absorptive section of the small intestine. The liver regulates the level of nutrients absorbed into the blood system from the small intestine. From the jejunum, whatever food that has not been absorbed is sent to the ileum which connects to the large intestine. The first part of the large intestine is the cecum and the second portion is the colon. The large intestine reabsorbs water and forms fecal matter.
   The TIM-1 system consists of a stomach compartment and 3 compartments for the small intestine, the duodenum, jejunum and ileum. The Tiny-TIM system consists of a stomach compartment and one single compartment for the small intestine. Samples can be harvested for analysis from these models from any compartment at any time.
  
  TIM-2 simulates the colon, containing the microbiota as found in human colon. This model serves as a tool to study fermentation of non-digestible food components (fibers and prebiotics) and the release of drugs specifically targeted for the colon.
  
  Section::::External links.
  
  BULLET::::- Website of TNO Triskelion
   Section::::Systematic response.:Digestive-system response.
  
  Section::::Systematic response.:Digestive-system response.:Cephalic phase.
   Section::::Initiating ingestion.:Metabolic signals.
  
  Hunger is the result of a fall in blood glucose level or depriving cells of the ability to metabolize fatty acids—glucoprivation and lipoprivation, respectively, stimulate eating. Detectors in the brain are only sensitive to glucoprivation; detectors in the liver are sensitive to both glucoprivation and lipoprivation outside the blood–brain barrier. However, no single set of receptors is solely responsible for the information the brain uses to control eating.
  
  Section::::Satiety signals.
   Section::::Systematic response.:Digestive-system response.:Enteric nervous system.
  
  The digestive system is also able to respond to internal stimuli. The digestive tract, or enteric nervous system alone contains millions of neurons. These neurons act as sensory receptors that can detect changes, such as food entering the small intestine, in the digestive tract. Depending on what these sensory receptors detect, certain enzymes and digestive juices from the pancreas and liver can be secreted to aid in metabolism and breakdown of food.
  
  Section::::Research methods and techniques.
  
  Section::::Research methods and techniques.:Clamping techniques.
   The first of the gut–brain interactions was shown to be between the sight and smell of food and the release of gastric secretions, known as the cephalic phase, or cephalic response of digestion.
  
  Section::::Gut–brain integration.
   Control of the digestive system is also maintained by ENS, which can be thought of as a digestive brain that can help to regulate motility, secretion and growth. Sensory information from the digestive system can be received, integrated and acted upon by the enteric system alone. When this occurs, the reflex is called a short reflex. Although this may be the case in several situations, the ENS can also work in conjunction with the CNS; vagal afferents from the viscera are received by the medulla, efferents are affected by the vagus nerve. When this occurs, the reflex is called vagovagal reflex. The myenteric plexus and submucosal plexus are both located in the gut wall and receive sensory signals from the lumen of the gut or the CNS.
   The TIM systems are being used to study the behavior of oral products during transit through the stomach, the small intestine and large intestine. Commonly performed studies concern the digestibility of food and food components, the bioaccessibility for absorption of pharmaceutical compounds, proteins, fat, minerals and (water- and fat-soluble) vitamins. 
  
  There are different models for the stomach and small intestine (TIM-1 and Tiny-TIM) and a model simulating the physiological conditions of the colon (TIM-2).
   In the absence of a gut compartment, input can be made directly in the liver. However, in that case local metabolism in the gut may not be correctly described. The case of approximately continuous absorption ("e.g. via" drinking water) can be modeled by a zero-order absorption rate (here "R" in units of mass over time):
  
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  More sophisticated gut absorption model can be used. In those models, additional compartments describe the various sections of the gut lumen and tissue. Intestinal pH, transit times and presence of active transporters can be taken into account
  
  Section::::Building a PBPK model.:Modeling inputs.:Skin depot.
   Every day, seven liters of fluid are secreted by the digestive system. This fluid is composed of four primary components: ions, digestive enzymes, mucus, and bile. About half of these fluids are secreted by the salivary glands, pancreas, and liver, which compose the accessory organs and glands of the digestive system. The rest of the fluid is secreted by the GI epithelial cells.
  
  Section::::Secretion.:Ions.
   The consequences of oral step can be observed at the beginning of the gastric digestion, the first stage. As there is no enzymatic proteolytic activity at this stage, the level of H-NMR, a spectrum used to determine the structure, is still constant because there is no change going on. However, when pepsin takes action, TD-NMR, a special technique used for measuring mobile water population with macromolecular solutes, reveals that progressive unbundling of meat fibers helps pepsin activity to digest. TD-NMR data proves that bolus structure changes considerably during the first part of digestion and water molecules, consequently, leave the spaces inside the myofibrils and fiber bundles. This results in a low level of water that can be detected in duodenal stage. Since digestion is in progress, protein molecules become smaller and molecular weight gets lower, in other words, there is an increase in the spectra total area.
   There are several sets of receptors located in the head: eyes, nose, tongue, and throat. The most important role of head factors in satiety is that taste and odor can serve as stimuli that permit learning about caloric contents of different foods. Tasting and swallowing of food contributes to the feeling of fullness caused by the presence of food in the stomach.
  
  Section::::Satiety signals.:Short-term signals.:Gastric and intestinal factors.
   Section::::Function of neurons in the gastrointestinal tract.:Segmentation.
  
  Segmentation contractions are the contractions in intestines carried out by the smooth muscle walls. Unlike peristalsis, which involves the contraction and relaxation of muscles in one direction, segmentation occurs simultaneously in both directions as the circular muscles alternatively contract. This allows for thorough mixing of intestinal contents, known as chyme, to allow greater absorption.
  
  Section::::Function of neurons in the gastrointestinal tract.:Secretion.
   Section::::Composition.:Systems.:Digestive system.
   The absorption of electrolytes and water is one of the most important functions of the digestive tract. Water absorption is passive and isotonic - depending on the speed and direction of solute flow. Other factors influencing fluid absorption are osmolarity and the specific intestinal region. Regulated selective permability is performed through two major routes: the transcellular (transepithelial) route and the paracellular route.
  
  Section::::Physiology.:Transcellular permeability.
   Section::::Components.:Pharynx.
   Regulation of gastric function
  
  The nervous system and endocrine system collaborate to increase gastric secretion and motility when food is eaten and to suppress them as the stomach empties. Gastric activity associated with eating is divided into three stages called the cephalic phase, gastric phase, and intestinal phase, based on whether the stomach is being controlled by the brain, by itself, or by the small intestine, respectively. These phases overlap and all three can occur simultaneously. 
   The small intestine is where most chemical digestion takes place. Many of the digestive enzymes that act in the small intestine are secreted by the pancreas and liver and enter the small intestine via the pancreatic duct. Pancreatic enzymes and bile from the gallbladder enter the small intestine in response to the hormone cholecystokinin, which is produced in the small intestine in response to the presence of nutrients. Secretin, another hormone produced in the small intestine, causes additional effects on the pancreas, where it promotes the release of bicarbonate into the duodenum in order to neutralize the potentially harmful acid coming from the stomach.
   The cephalic phase is the stage in which the stomach responds to the mere sight, smell, taste, or thought of food. About 30% of total acid secretion occurs before food enters the stomach. These sensory and mental inputs converge on the hypothalamus, which relays signals to the medulla oblongata. Vagus nerve fibers from the medulla stimulate the parasympathetic nervous system of the stomach which, in turn, stimulates gastric secretion (via parietal and G cells).
  
  Section::::Cephalic Phase.:Chain of Events.
   Section::::Function.:Absorption.
   The enteric nervous system in humans consists of some 500 million neurons (including the various types of Dogiel cells), 0.5% of the number of neurons in the brain, five times as many as the one hundred million neurons in the human spinal cord, and about 2/3 as many as in the whole nervous system of a cat. The enteric nervous system is embedded in the lining of the gastrointestinal system, beginning in the esophagus and extending down to the anus.
  
presuppositions: Your stomach knows the difference between food/liquid - bowels/bladder. The stomach knows the difference between food and liquid.
corrections: Your stomach does not know the difference between food/liquid - bowels/bladder. The stomach doesn't know the difference between food and liquid but various parts of the body handle the breakdown and digestion of these substances differently. 
raw_presuppositions: Your stomach knows the difference between food/liquid - bowels/bladder. The stomach knows the difference between food and liquid.
raw_corrections: Your stomach does not know the difference between food/liquid - bowels/bladder. The stomach doesn't know the difference between food and liquid but various parts of the body handle the breakdown and digestion of these substances differently. 