Digestive Enzymes These exist in the alimentary Digestion is the process of tract making food absorbable by Purpose - breaking down dissolving it into simpler components of food so that chemical components. This they can be absorbed by the occurs in the body chiefly body. through the action of The main sites of action are digestive enzymes. the oral cavity, the stomach, the duodenum and the Enzymes are “molecular machines that do useful jejunum. work. Some manufacture large, complex molecules for use in the cell. Others take molecules apart, They are secreted by different breaking them down into their raw material to be glands: the salivary glands, recycled.” the glands in the stomach, - Hari Sharma, MD the pancreas, and the glands in the small intestines.
Ailmentary Tract Includes the Upper and Lower Gastrointestinal tracthttp://en.wikipedia.org/wiki/Alimentary_tract
The Mouth Starts Everything Moving Even before you eat, when Your tongue helps out, you smell a tasty food, see pushing the food around it, or think about it, while you chew with your digestion begins. teeth. Saliva begins to form in When youre ready to your mouth. When you do swallow, the tongue eat, the saliva breaks pushes a tiny bit of down the chemicals in the masticated food called a food a bit, which helps bolus toward the back of make the food mushy and your throat and into the easy to swallow. opening of your esophagus, the second part of the digestive tract.
Oral Cavity In the oral cavity, salivary glands secrete ptyalin. It is a type of amylase, which digests starch into small segments of multiple sugars and into individual soluble sugars. Secreted by small and large salivary glands. Salivary glands also secrete lysozyme, which kills bacteria but is not classified as a digestive enzyme.
The Esophagus http://www.plwc.org/oncology_content/content_images/esophagus_credit_large.jpg The esophagus is like a stretchy pipe thats about 10 inches (25 centimeters) long. It moves food from the back of your throat to your stomach. But also at the back of your throat is your windpipe, which allows air to come in and out of your body.
Esophagus When you swallow food or liquids, a special flap called the epiglottis covers over the opening of your windpipe to make sure the food enters the esophagus and not the windpipe. If youve ever drunk something too fast, started to cough, and heard someone say that your drink "went down the wrong way," the person meant that it went down your windpipe by mistake. This happens when the epiglottis doesnt have enough time to flop down, and you cough involuntarily to clear the windpipe. Once food has entered the esophagus, it doesnt just drop right into the stomach. Instead, muscles in the walls of the esophagus move in a wavy way (peristaltia) which slowly squeezes the food through the esophagus. This takes about 2 or 3 seconds.
Stomach Your stomach is attached to the end of the esophagus. It has three important jobs:to store the food youve eaten; break down the food into a liquidy mixture; and slowly empty that mixture into the small intestine.http://www.bupa.co.uk/health_information/images/organ/stomach.gif
Stomach The stomach is like a mixer, churning and mashing together all the small balls of food that came down the esophagus into smaller and smaller pieces. It does this with help from the strong muscles in the walls of the stomach and gastric juices that also come from the stomachs walls. In addition to breaking down food, gastric juices also help kill bacteria that might be in the eaten food. The enzymes that get secreted in the stomach are called gastric enzymes.
Enzymes in the Stomach Pepsin is the main gastric enzyme. It breaks proteins Pepsin in complex with pepstatin into small peptide fragments, it is a peptidase. Gelatinase, degrades gelatin and collagen, which are the proteoglycans found in meat. Gastric amylase degrades starch, but is of minor significance. Gastric lipase is a tributyrase by its biochemical activity, http://en.wikipedia.org/wiki/Pepsin because it acts almost exclusively on tributyrin, a butter fat
Pancreas The pancreas is the main digestive gland in our body. It secretes many different enzymes - proteases, nucleases and an amylasehttp://en.wikipedia.org/wiki/Pancreas
Pancreatic enzymes Trypsin, is a peptidase, like pepsin in the stomach. Chymotrysin, is also a peptidase. Steapsin, is a carbohydrate digesting enzyme. Carboxypeptidase splits peptide fragments into individual amino acids. It is a protease. Several elastases degrade the protein elastin and other proteins. Several nucleases degrade nucleic acids, like DNAase and RNAase. Pancreatic amylase, besides starch and glycogen, degrades also most other hydrocarbons, but not cellulose . Forming disaccharides and trisaccharides. Bile from the Liver, emulsifies fat, allowing more efficient use of the lipase enzyme in the duodenum. This converts lipids to their component fatty acid and glycerol molecules.
The Small Intestine The small intestine is a long tube thats about 1 1/2 inches to 2 inches (about 3.5 to 5 centimeters) around, and its packed inside you beneath your stomach. If you stretched out an adults small intestine, it would be about 22 feet long (6.7 meters). The small intestine breaks down the food mixture even more so your body can absorb all the vitamins, minerals, proteins, carbohydrates, and fats from your food. The small intestine can help extract them - with a little help from the pancreas, liver, and gallbladder. These organs send different juices to the first part of the small intestine. The juices help to digest food and allow the body to absorb nutrients. The pancreas makes juices that help the body digest fats and protein. - pancreatic enzymes. Your food may spend as long as 4 hours in the small intestine and will become a very thin, watery mixture. The nutrients from food can pass from the small intestine into the blood stream. Once in the blood, your body is closer to benefiting from complex carbohydrates, vitamins, proteins, and minerals. The next stage in digestion is the liver. And the leftover waste - remnants of the food that your body cant use - goes on to the large intestine.
Small Intestine http://en.wikipedia.org/wiki/Jejunum The jejunum and ileum secretes a juice called succus entericus which contains six types of enzymes that degrade disaccharides into monosaccarides - these are considered peptidases.
Peptidases - enzymes Sucrase, breaks down sucrose Sucrose, a common disaccharide into glucose and fructose Maltase, breaks down maltose into glucose. Isomaltase, breaks down maltose and isomaltose Lactase, breaks down lactose into glucose and galactose Intestinal lipase, breaks down fatty acids Erepsin, is a protein-digesting enzymehttp://en.wikipedia.org/wiki/Digestive_enzyme
Liver and Gallbladder Nutrient-rich blood comes directly The gallbladder serves as a to the liver for processing. warehouse for bile, storing it A juice from the liver called bile until the body needs it. helps to absorb fats into the bloodstream. The liver filters out harmful substances or wastes, turning some of the waste into more bile. The liver even helps figure out how many nutrients will go to the rest of the body, and how many will stay behind in storage. For example, the liver stores certain vitamins and a type of sugar your body uses for energy. http://www.britishlivertrust.org.uk/content/liver/images/liver-biliarytract.gif
Large Intestine At 3 or 4 inches around (about 7 to 10 centimeters), the large intestine is fatter than the small intestine and its almost the last stop on the digestive tract. Like the small intestine, it is packed into the body, and would measure 5 feet (about 1.5 meters) long if you spread it out. The large intestine has a tiny tube with a closed end coming off it called the appendix. Its part of the digestive tract, but it doesnt seem to do anything, though it can cause big problems, because it sometimes gets infected and needs to be removed. The large intestine, or colon, may be divided into the cecum,http://www.becomehealthynow.com/popups/lrg_intest.htm ascending colon, transverse colon, descending colon, and sigmoid colon.
Digestive Waste After most of the nutrients are removed from the digested food, there is waste left over - stuff your body cant use. This becomes feces. This passes through the part of the large intestine called the colon - which is where the body gets its last chance to absorb the water and some minerals into the blood. As the water leaves the waste product, whats left gets harder and harder as it keeps moving along, until it becomes a solid. The large intestine pushes the feces into the rectum, the very last stop on the digestive tract. The solid waste stays here until the body is ready to make a bowel movement- pushing it through the anus
A Healthy Digestive System You can help your digestive system by drinking plenty of water and eating a healthy diet that includes organic, fresh foods rich in fiber. High-fiber foods, like fruits, vegetables, and whole grains, make it easier for digested food to pass through your system and keeps your colon healthy. The digestive system is a very important part of your body. Without it, you couldnt get the nutrients you need to grow and repair properly or stay youthful and healthy.
Resourceshttp://www.kidshealth.orghttp://en.wikipedia.orghttp://www.bupa.co.ukhttp://www.plwc.orghttp://www.becomehealthynow.comhttp://www.britishlivertrust.orgFreedom from Disease; Hari Sharma; Veda Publishing;Toronto; 1993.Merriam Webster’s Medical Desk Dictionary; Merriam-Webster Inc.; Springfield, MA; 1993.