question: How do we excrete solid waste without flushing the fluids out of our stomachs?
comment: Well you have muscular sphincters and such that constrict and relax to allow or stop food from passing. Soluable fiber acts like kind of a gelatin to absorb water and turn poos solid. Plus I think one of your large intestine's jobs is to absorb liquid from the waste as it passes through so you don't open up like a high powered lawn sprinkler upon pooing. Usually.
passages: 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.
   There are three main sites where drug excretion occurs. The kidney is the most important site and it is where products are excreted through urine. Biliary excretion or fecal excretion is the process that initiates in the liver and passes through to the gut until the products are finally excreted along with waste products or feces. The last main method of excretion is through the lungs (e.g. anesthetic gases).
  
  Excretion of drugs by the kidney involves 3 main mechanisms:
  
  BULLET::::- Glomerular filtration of unbound drug.
   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 large intestine's main function is to transport food particles through the body and expel the indigestible parts at the other end, but it also collects waste from throughout the body. The typical brown colour of mammal waste is due to bilirubin, a breakdown product of normal heme catabolism. The lower part of the large intestine also extracts any remaining usable water and then removes solid waste. At about 10 feet long in humans, it transports the wastes through the tubes to be excreted.
  
  Section::::Systems.:Biliary system.
   Water and saliva enter through the rumen to form a liquid pool. Liquid will ultimately escape from the reticulorumen from absorption through the wall, or through passing through the reticulo-omosal orifice, as digesta does. However, since liquid cannot be trapped in the mat as digesta can, liquid passes through the rumen much more quickly than digesta does. Liquid often acts as a carrier for very small digesta particles, such that the dynamics of small particles is similar to that of liquid.
   Section::::Systems.:Urinary system.:Kidneys.
  
  The kidney's primary function is the elimination of waste from the bloodstream by production of urine. They perform several homeostatic functions such as:-
  
  BULLET::::1. Maintain volume of extracellular fluid
  
  BULLET::::2. Maintain ionic balance in extracellular fluid
  
  BULLET::::3. Maintain pH and osmotic concentration of the extracellular fluid.
  
  BULLET::::4. Excrete toxic metabolic by-products such as urea, ammonia, and uric acid.
   HO also diffuses out of the cell into the blood stream, from where it is excreted in the form of perspiration, water vapor in breath, or urine from the kidneys. Water, along with some dissolved solutes, are removed from blood circulation in the nephrons of the kidney and eventually excreted as urine.
  
  The products of fermentation can be processed different ways, depending on the cellular conditions.
   Section::::Products.:Wastewater.
  
  The final output from anaerobic digestion systems is water, which originates both from the moisture content of the original waste that was treated and water produced during the microbial reactions in the digestion systems. This water may be released from the dewatering of the digestate or may be implicitly separate from the digestate.
   The colon is the last part of the digestive system. It extracts water and salt from solid wastes before they are eliminated from the body and is the site in which flora-aided (largely bacterial) fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a major role in absorption of foods and nutrients. About 1.5 litres or 45 ounces of water arrives in the colon each day.
   Section::::Substances.
  
  Section::::Substances.:Bile.
  
  After bile is produced in the liver, it is stored in the gall bladder. It is then secreted within the small intestine where it helps to emulsify fats in the same manner as a soap. Bile also contains bilirubin, which is a waste product.
   Within the kidney, blood first passes through the afferent artery to the capillary formation called a glomerulus and is collected in the Bowman's capsule, which filters the blood from its contents—primarily food and wastes. After the filtration process, the blood then returns to collect the food nutrients it needs, while the wastes pass into the collecting duct, to the renal pelvis, and to the ureter, and are then secreted out of the body via the urinary bladder.
  
  Section::::Clinical signifiance.
  
  Section::::Clinical signifiance.:Kidney Stones.
   In the large intestine the passage of food is slower to enable fermentation by the gut flora to take place. Here water is absorbed and waste material stored as feces to be removed by defecation via the anal canal and anus.
  
  Section::::Human digestion process.:Neural and biochemical control mechanisms.
  
  Different phases of digestion take place including: the cephalic phase, gastric phase, and intestinal phase.
   The urinary system consists of the kidneys, ureters, bladder, and urethra. It removes toxic materials from the blood to produce urine, which carries a variety of waste molecules and excess ions and water out of the body.
  
  Section::::Anatomy.
   The major part of digestion takes place in the small intestine. The large intestine primarily serves as a site for fermentation of indigestible matter by gut bacteria and for resorption of water from digests before excretion.
   Section::::Formation of urine.:Reabsorption.
  
  Tubular reabsorption is the process by which solutes and water are removed from the tubular fluid and transported into the blood. It is called "reabsorption" (and not "absorption") both because these substances have already been absorbed once (particularly in the intestines) and because the body is reclaiming them from a postglomerular fluid stream that is well on its way to becoming urine (that is, they will soon be lost to the urine unless they are reclaimed).
   Although the strictest sense of the word "excretion" with respect to the urinary system is urination itself, renal clearance is also conventionally called excretion (for example, in the set term "fractional excretion of sodium").
  
  Section::::Formation of urine.:Filtration.
   Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. In chemical digestion, enzymes break down food into the small molecules the body can use.
   It occurs when insufficient fluid is absorbed by the colon. As part of the digestion process, or due to fluid intake, food is mixed with large amounts of water. Thus, digested food is essentially liquid prior to reaching the colon. The colon absorbs water, leaving the remaining material as a semisolid stool. If the colon is damaged or inflamed, however, absorption is inhibited, and watery stools result.
   There are several organs and other components involved in the digestion of food. The organs known as the accessory digestive glands are the liver, gall bladder and pancreas. Other components include the mouth, salivary glands, tongue, teeth and epiglottis.
  
  The largest structure of the digestive system is the gastrointestinal tract (GI tract). This starts at the mouth and ends at the anus, covering a distance of about nine (9) metres.
  
  The largest part of the GI tract is the colon or large intestine. Water is absorbed here and the remaining waste matter is stored prior to defecation.
   In the ventral reticulum, less dense, larger digesta particles may be propelled up into the oesophagus and mouth during contractions of the reticulum. Digesta is chewed in the mouth in a process known as rumination, then expelled back down the oesophagus and deposited in the dorsal sac of the reticulum, to be lodged and mixed into the ruminal mat again. Denser, small particles stay in the ventral reticulum during reticular contraction, and then during the next contraction may be swept out of the reticulorumen with liquid through the reticulo-omasal orifice, which leads to the next chamber in the ruminant animal's alimentary canal, the omasum.
   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.
   In some cases, reabsorption is indirect. For example, bicarbonate (HCO) does not have a transporter, so its reabsorption involves a series of reactions in the tubule lumen and tubular epithelium. It begins with the active secretion of a hydrogen ion (H) into the tubule fluid via a Na/H exchanger:
  
  BULLET::::- In the lumen
  
  BULLET::::- The H combines with HCO to form carbonic acid (HCO)
  
  BULLET::::- Luminal carbonic anhydrase enzymatically converts HCO into HO and CO
  
  BULLET::::- CO freely diffuses into the cell
  
  BULLET::::- In the epithelial cell
   One of the main functions of the colon is to remove the water and other key nutrients from waste material and recycle it. As the waste material exits the small intestine through the ileocecal valve, it will move into the cecum and then to the ascending colon where this process of extraction starts. The unwanted waste material is moved upwards toward the transverse colon by the action of peristalsis.
  
  The ascending colon is sometimes attached to the appendix via Gerlach's valve. In ruminants, the ascending colon is known as the spiral colon.
   After some time (typically 1–2 hours in humans, 4–6 hours in dogs, 3–4 hours in house cats), the resulting thick liquid is called chyme. When the pyloric sphincter valve opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas and bile juice from the liver and then passes through the small intestine, in which digestion continues. When the chyme is fully digested, it is absorbed into the blood. 95% of absorption of nutrients occurs in the small intestine. Water and minerals are reabsorbed back into the blood in the colon (large intestine) where the pH is slightly acidic about 5.6 ~ 6.9. Some vitamins, such as biotin and vitamin K (KMK7) produced by bacteria in the colon are also absorbed into the blood in the colon. Waste material is eliminated from the rectum during defecation.
   Section::::Clinical signifiance.:Kidney Stones.:Treatment.
  
raw_presuppositions: We dont flush fluids out of our stomach.
raw_corrections: Large intestines absorbs liquid from the waste. 