Why is it necessary for the pancreas to secrete a high pH (basic) solution into the small intestine?
None of the choices is correct. The reason for neutralizing stomach acid is NOT to protect the intestine--intestinal goblet cells secrete mucus for that. The main reason is that the digestive enzymes coming from the pancreas--the proteases, the lipases, and amylase--would be inactive at acid pH. Pancreatic juice has a lot of bicarbonate buffer in it--that raises the pH of the incoming chyme from about 1-2 to around 6-7--so that the digestive enzymes will be active.
Describe protein digestion in the stomach and small intestines?
Stomach is a J shaped expandable organ located on the left side of the abdominal cavity. It stores up to 2 liters of food while mixing and digesting it. The epithelial cells secrete Gastric juices and HCl making the pH around 2. Pepsin is an enzyme used to partially hydrolyze protein. Pepsin is released in an inactive form Pepsinogen. The pepsinogen reacts with HCl to form pepsin. The hormone gastrin is secreted by the stomach cells to regulate the production of gastric juices. The stomach is closed at its posterior end by the pyloric sphincter. Small Intestine: Most hydrolysis of macromolecules occur in the small intestine. It is more than 6 meters in length. It has smaller diameter than that of the large intestine. It is divided into 3 sections (Duodenum, Jejunum, and ileum). Accessory Organs ( Pancreas, Liver, and Gall Bladder), add digestive enzymes, juices and hormones into the small intestine. As the acid chyme enters the duodenum (first 25 cm of the small intestine) a hormone called secretin is released from the intestinal walls to siginal the pancreas to release a bicarbonate solution which neutralizes the acid. The hormone CHOLECYSTOKININ (CCK), is released from the intestinal cells causing the gall bladder to release bile. It also causes the pancreas to release its digestive enzymes. The hormone ENTEROGESTRONE is also secreted to slow down peristalsis. Protein Digestion: Trypsin and Chymotrypsin are enzymes that break bonds next to specific amino acids. Carboxypeptidase splits off one amino acid at a time. This enzyme works on the end with the free carboxyl group. Aminopeptidase works in the opposite direction. All the above enzymes are secreted in an inactive form. They are activated by the hormone ENTEROKINASE. Fat Digestion: Bile emulsifies fat. This creates a larger surface area for the enzyme lipase to digest it. Carbohydrate Digestion: Disaccharide digestion is under the control of the enzymes maltase, lactase, sucrase.
Where in the digestive tract digestion of carbohydrates, proteins, and fats take place?....?
What are the brakedown products of these sources of energy? How do the Breakdown products make it into the blood stream to travel to the cells that will ultimately use them?
What human fluids fluid (saliva, tears, etc.) are basic, and which of them are acid?
Gastric acid - WikipediaThe pH of gastric acid is 1.5 to 3.5[1] in the human stomach lumen,The parietal cell releases bicarbonate into the bloodstream in the process, which causes a temporary rise of pH in the blood.In the duodenum, gastric acid is neutralized by sodium bicarbonate. This also blocks gastric enzymes that have their optima in the acid range of pH. The secretion of sodium bicarbonate from the pancreas is stimulated by secretin.The cells that make HCl for stomach acid also make NaHCO3 for the blood.Pancreatic juice - WikipediaPancreatic juice is alkaline in nature due to the high concentration of bicarbonate ions. Bicarbonate is useful in neutralizing the acidic gastric acid, allowing for effective enzymic action. …Pancreatic secretion is an aqueous solution of bicarbonate originating from the duct cells and enzymes originating from the acinar cells. …Pancreatic juice is secreted into the duodenom through duodenal papilla. Some individuals have also an accessory duct, named accessory pancreatic duct…So, digestive enzymes meant to work in the stomach need an acid pH. Digestive enzymes meant to work in the small intestines need a neutral pH. In other words the body uses pH control to control enzyme activation. Very interesting.
Why is protein the only macronutrient (fat, protein and carbohydrate) to not begin breaking down via enzyme in the mouth?
Your question should be - Why are Carbohydrates the only macro-nutrients to be digested from the mouth? Most of the lipid digestion (more 90%) occurs in the small intestine. Lipids are fat and are mostly hydrophobic. In the aqueous environment present in mouth and stomach the lipids would remain as chunks and could not be digested. In the intestine the Bile salts from the gall would emulsify the fat into tiny droplets making the digestion of fat easier. Most proteins are stably at neutral pH requires low pH to denatured. (Refer Brian Farley's answer here for explanation)So as you can see the digestion of fats and proteins cannot begin from mouth because lipids would require a oily environment. While the digestion of proteins require a very low pH, which is not possible outside stomach. Stomach walls are protected by mucous. But mucous in mouth and esophagus would affect breathing.DNases and RNase are secreted by pancreas and the digestion of nucleic acids do not occur from mouth. I do not have a proper explaination for this. But could be that they are not very important (there is little DNA or RNA in food) to be digested right from the mouth.
If our stomach bile is so acidic, then is it possible for our feces to eventually be destroyed by the bile soaked in them?
No.Every theory needs to be based on observation - there are no people with the described bowel destruction, so it does not happen.This is because the stomach acid is neutralised by alkaline secretions from the pancreas which are ejected into the duodenum along with some bile as the food passes by.Although Hydrochloric Acid is a strong acid, it is produced only in sufficient quantities by the stomach so the food itself will neutralise much of the acid. Also, though strong acids have a very low pH, they are easy to neutralise.pH is the ‘inverse log’ of the concentration of hydrogen ions in the solution. A strong acid will release all it’s hydrogen ions at once, making for a high concentration of them, and a low pH. Though this makes them powerful, as the ions are used up doing damage or being neutralised by alkali, the pH rises rapidly and it does not take much alkali to do this. It’s a different matter with weak acids like citric acid found in fizzy drinks. These damage more slowly but equally surely and take a lot more alkali to neutralise so they really damage your teeth…
Where do enzymes break down food in the digestive system?
1. Saliva is secreted to moisten food, protect the mouth from abrassions, buffer against acids in food, kill some forms of bacteria, and begin carbohydrate digestion with the enzyme SALIVARY AMYLASE. 2. Stomach: Stores up to 2 liters of food while mixing and digesting it. The epithelial cells secrete GASTRIC JUICES and HCl making the pH around 2. PEPSIN is an enzyme used to partially hydrolyze protein. Pepsin is released in an inactive form PEPSINOGEN. The pepsinogen reacts with HCL to form pepsin. The hormone GASTRIN is secreted by the stomach cells to regulate the production of gastric juices. 3. Small Intestine: Most hydrolysis of macromolecules occur in the small intestine. It is more than 6 meters in length. It has smaller diameter than that of the large intestine. It is divided into 3 sections ( Duodenum, Jejunum, and ileum). Accessory Organs ( Pancreas, Liver, and Gall Bladder), add digestive enzymes, juices and hormones into the small intestine. As the acid chyme enters the duodenum (first 25 cm of the small intestine) a hormone called SECRETIN is released from the intestinal walls to siginal the pancreas to release a bicarbonate solution which neutralizes the acid. The hormone CHOLECYSTOKININ (CCK), is released from the intestinal cells causing the gall bladder to release bile. It also causes the pancreas to release its digestive enzymes. The hormone ENTEROGESTRONE is also secreted to slow down peristalsis. Protein Digestion: Trypsin and Chymotrypsin are enzymes that break bonds next to specific amino acids. Carboxypeptidase splits off one amino acid at a time. This enzyme works on the end with the free carboxyl group. Aminopeptidase works in the opposite direction. All the above enzymes are secreted in an inactive form. They are activated by the hormone ENTEROKINASE. Fat Digestion: Bile emulsifies fat. This creates a larger surface area for the enzyme lipase to digest it. Carbohydrate Digestion: Disaccharide digestion is under the control of the enzymes maltase, lactase, sucrase.
Which part of the digestive system are starches digested by enzymes?
Well,its not just one part but many parts in fact. =)First of all,starch digestion initiates in the mouth (buccal cavity), mechanical digestion takes place by the teeth,jaws,and tongue and chemical digestion of starch occurs by the saliva secreted by the three pairs of salivary glands. The enzyme salivary amylase or ptyalin digests starch into maltose. ( if you chew rice for a long time you get a sweet taste in your mouth cuz of the maltose).Undigested and partly digested starch then moves through the oesophagus and into the stomach.Starch isn't particularly chemically digested in the stomach but its mechanically digested to a certain extent by muscular churning in the stomach.Then,the semi solid formed called chyme enters the small intestine. In the duodenum the pancreas secretes amylase which digests the undigested carbs into maltose. As the chyme passes through to the jejunum the intestinal juices secrete maltase,sucrase and lactase which in turn digests maltose,sucrose and lactose into their relevant end products,their monosaccharides. Thus,starch digestion occur s as such. ;D