When our body is in good health, our Blood is slightly alkaline and Urine slightly acidic. The delicate acidity alkalinity balance in our body largely depends up on the food we eat. The acid forming types of food are chiefly all the animal proteins, such as meat, egg, fish and cheese, the starchy or sugary food such as cereals and sugar. The alkali-forming foods are vegetables and fruits. Phosphorous, Sulphur, Chlorine, Iodine, carbon dioxide, Lactic acid, Uric acid present in the food contribute to the acidic effect. Sodium and its salts, Potassium, Calcium, Iron, Copper, Magnesium, and manganese present in the food contribute to the alkaline effect.
It is the correct balance between the acidity and alkalinity which leads to good health. Acidic and basic are two extremes that describe a chemical property. Mixing acids and bases can cancel out or neutralize their extreme effects. A substance that is neither acidic nor basic is neutral. The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic. Human blood stays in a very narrow pH range right around (7.35 - 7.45). Below or above this range means symptoms and disease. If blood pH moves too much below 6.8 or above 7.8, cells stop functioning and the patient dies. The ideal pH for good health the balance should be around 7.4pH that are slightly alkaline. A change in the balance leads to various diseases. It is told that extreme acidity causes diabetes and extreme alkalinity causes cancer.
What does pH mean? pH is the abbreviation for potential hydrogen. The pH of any solution is the measure of its hydrogen-ion a positively charged atom of hydrogen; that is to say, a normal hydrogen atomic nucleus concentration. The human body is composed of various organs and parts, which are made up of tissues and cells. These tissues and cells are composed of chemical elements. The balance or equilibrium of these chemical elements in the body is an essential factor in the maintenance of health and healing of disease. The acid-alkaline balance plays a vital role in this balanced body chemistry. The higher the pH reading, the more alkaline and oxygen rich the blood is. The lower the pH reading, the more acidic and oxygen deprived the blood is. The normal body chemistry is approximately 20 per cent acid and 80 per cent alkaline. This is the acid-alkaline balance.
When unbalanced diet is taken, toxins are formed, and when these toxins are not completely eliminated by the body, they damage various organs of the body. One must eat right food in right proportion to keep the blood purified and to maintain the correct acidity-alkalinity balance. All foods, after digestion and absorption leave either an acid or alkaline ash in the body depending on their mineral composition. In normal health, the reaction of the blood is alkaline and that is essential for our physical and mental well-being. The preponderance of alkalis in the blood is due to the fact that the products of the vital combustions taking place in the body are mostly acid in character. Carbohydrates and fats form about nine-tenths of the normal fuel of the body. IN normal health, this great mass of material is converted into carbon dioxide gas and water. Half of the remaining one-tenth fuel is also converted into the same gas and water. Thus toxin is a by-product as constant and necessary as life itself. This huge amount of toxin is transported by the blood to the various points of discharge, mainly the lungs. When the organism is normal by virtue of alkalinity, the blood is able to transport the acid from the point of production to the point of elimination the discharge points and eliminated as fast as produced. Hence at no time the organism free from toxin acid in the blood. In a normal amount it is gently stimulating; but when the organism is enervated, elimination is checked. Then the amount retained will be over stimulating- toxic-acidic ranging from a slight excess to an amount so profound as to overwhelm life.
Whenever the alkalinity of the blood is reduced, even slightly, its ability to transport the carbon dioxide gets reduced. This results in the accumulation of acid in the tissues. This condition is known as acidosis or hypo-alkalinity of the blood. Its symptoms are hunger, indigestion, burning sensation and pain in the pharynx, nausea, vomiting, headache, various nervous disorders and drowsiness. Acidosis is the breeding ground for most diseases. It seriously interferes with the functions of the glands and organs of the body. It also lowers the vitality of the system, thereby increasing the danger of infectious diseases. The main cause of acidosis or hypo-alkalinity of the blood is faulty diet, in which too many acid forming foods have been consumed. In the normal process of metabolism or converting the food into energy by the body, various acids are formed in the system and in addition, other acids are introduced in food. Whenever there is substantial increase in the formation of acids in the system and these acids are not properly eliminated through the lungs, the kidneys and the bowels, the alkalinity of the blood is reduced, resulting in acidosis.
Acidosis can be prevented by maintaining a proper ratio between acid and alkaline foods in the diet. Certain foods leave alkaline ash and help in maintaining the alkalinity of the food, while others leave highly acid ash and lower the alkali reserve of the blood and tissue fluids to a very large extent. Our daily diet should consist of four-fifth of alkaline-forming foods such as juicy fruits, tubers, legumes, ripe fruits, leafy and root vegetables and one fifth of acid-forming foods containing concentrated proteins and starches such as meat, fish, bread and cereals. Eating sensibly in this manner will ensure the necessary alkalinity of the food which will keep the body in perfect health. Whenever a person has acidosis, the higher the ratio of alkaline- forming foods in his diet, the quicker will be the recovery. Acids are neutralized by alkalis. It is, therefore, imperative that persons suffering from various ailments are given adequate alkaline ash foods to offset the effects of acid-forming foods and leave a safe margin of alkalinity.
The most agreeable and convenient means of alkalizing the blood are citrus fruits and fruit juices. It is an error to presume that because a food tastes acid, it has an acidic reaction in the blood. The alkalizing value of citrus fruits is due to large percentage of alkaline salts, mainly potash, which they contain. Each pint of orange juice contains 12 grains of potassium, one of the most potent of alkalis. Lemon juice contains nine grains of the alkali to the pint and grape seven grains. When the acids are burnt or utilized in the body, the alkaline soda or potash is left behind. The acid of the citrus fruits do not increase the acidity of the body, Acid salts of organic acids lose their acidity when they are oxidized within the body and only their alkaline carbohydrates are left. Hence the effect of the natural fruit acids is to increase the alkalinity of the blood rather than reduce it. In this way all citrus fruits have an alkaline effect.
As discussed above the effect of food stuffs upon the alkalinity of the blood depends upon their residue which they leave behind after undergoing oxidation in the body. Major food groups leaving an Acid Ash after oxidation in the body (One-Fifth Class) are Barley Eggs, Bananas (unripe) Grain Foods, Beans Lentils, Bread, Meats, Cereals, Nuts except almonds, Cakes Oatmeal, Chicken Peas, Confections Rice, Corn Sugar, Chocolate Sea Foods & Coffee Tea
Major food groups leaving an Alkaline Ash ( Four-fifth class ) are Almonds Melons, Apples Milk, Apricots Onions, Banana (ripe), Oranges, Beets Parsley, Cabbage Peaches, Carrots Pears, Cauliflower Pineapple, Celery Potatoes, Coconuts, Pumpkins, Cottage, Cheese, Radishes, Cucumbers, Raisins, Dates Spinach, Figs (Fresh and Dry), Soya beans, Grapes, Tomatoes, Lemons Turnips, Lettuce.
Food is our fuel and its nutrients give our body cells the energy and the substances they need to operate. But before food can do that it must be digested in to small pieces the body can absorb and use.
Every morsel of the food we eat has to be broken down in to nutrients that can be absorbed by the body, which is why it takes hours to fully digest the food. This chemical part of digestion is accomplished by a series of juices and their enzymes. The juices alternate between alkalis and acids, and their character is determined by the requirement of the enzymes they contain. These enzymes remain active in suitable media of well defined acid-alkaline ranges and are destroyed in unsuitable media.
Digestion begins in the mouth, well before food reaches the stomach. When we see, taste, smell, or even imagine a tasty meal our salivary glands which are located under the tongue near the lower jaw begin producing saliva. The flow of saliva is set in motion by a brain reflex that triggered when we sense food or think about eating. In response to this sensory stimulation, the brain sends impulses through the nerves that control the salivary glands, telling them to prepare for a meal. As the teeth tear and chop the food, saliva moistens it for easy swallowing. A digestive enzyme called amylase (ptyalin) which is found in saliva starts to break down some of the carbohydrates (starches and sugars) in the mouth even before it leaves the mouth. The salivary amylase (ptyalin) or starch-splitting enzyme of the mouth is active only in an alkaline media and is destroyed by a mild acid. The pH in the human digestive tract varies greatly (see Human Digestive Tract pH Range Chart below). The pH of saliva is usually remains 6.5 - 7.5.
pH is the (from potential of Hydrogen) logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is more basic and less than 7 is more acidic)
Swallowing, which is accomplished by the muscle movements in the tongue and mouth, moves the food in to the throat (Pharynx-A passage way for food and air about 5 inches long) A flexible flap of tissue called epiglottis reflexively closes over wind pipe when we swallow to prevent food entering into wind pipe.
From the throat food travels down a muscular tube in the chest called esophagus. Waves of muscles contractions called peristalsis force food down through the esophagus to the stomach. At the end of esophagus, a muscular ring or valve called sphincter allows the food enter the stomach and then squeezes shut to keep food or fluid from flowing back up into the esophagus. The stomach muscles churn and mix the food with acids and enzymes, breaking it into much smaller digestible pieces. The stomach has three mechanical tasks. First it stores the swallowed food and liquid. The muscle of the upper part of the stomach relaxes to accept the large volumes of swallowed material. The second job is to mix up the food, liquid and digestive juice produced by the stomach. The lower part of the stomach mixes these materials by its muscle action churning. The third task of stomach is to empty its contents slowly into small intestine.
An acidic environment is needed for the digestion that takes place in the stomach. The upper portion of the stomach which has a pH between 4.0 - 6.5. This is where "predigest ion" occurs while the lower portion of the stomach is secreting hydrochloric acid (HCI) and pepsin until it reaches a pH range 1.5 - 4.0. Glands in the stomach lining produce about 3 quarts (2.8liters) of these digestive juices every day.
Most substances in the food we eat need further digestion and must travel into the small intestine. By the time food is ready to leave the stomach, it has been processed in to thick liquid called chime. A walnut sized muscular valve at the outlet of the stomach called the pylorus keep chime in the stomach until it reaches the right consistency to pass in to small intestine. Chime is then squirted down into small intestine where digestion of food continues so the body can absorb the nutrients into the blood stream.
The small intestine is made up of three parts. 1. Duodenum (the C shaped first part). 2. Jejunum (the coiled mid section). 3. Ileum (the final section that leads into large intestine). The liver, the gallbladder and the pancreas are not part of alimentary canal but these organs are essential to digestion.
The liver produces bile, which helps the body absorb fat. Bile is stored in the gallbladder until it is needed. The pancreas produces enzymes that help digest proteins, fats and carbohydrates. It also makes a substance that neutralizes stomach acid. After the food mix with the pancreatic juice the pH range changes to 7.0 - 8.5. These enzymes and bile travel through special channels called ducts directly into Duodenum where they help to breakdown the food.
The liver also plays major role in handling and processing nutrients which are carried to the liver in the blood from small intestine.
From the small intestine the undigested food and some water travels into the large intestine through a muscular ring or valve that prevents food from returning into small intestine. By the time food reaches the large intestine, the work of absorbing nutrients is nearly finished. The large intestine’s main function is to remove water from the undigested matter and form solid waste that can be excreted. While the waste products are passed out through the colon the pH ranges 4.0 - 7.0.
The large intestine is made up of three parts. 1. The Cecum- is a pouch at the beginning of large intestine that joins the small intestine to the large intestine. This transition area expands in diameter, allowing food to travel from the small intestine to the large. The appendix, a small, hollow, finger like pouch, hangs at the end of the cecum. Doctors believe the appendix is a left over from previous time in human evolution. It no longer appears to be useful to the digestive processes. 2. The colon extends from the cecum up the right side of the abdomen (Ascending colon), across the upper abdomen (transverse colon) and then down the left side of the abdomen (descending colon) finally connecting to the rectum. Bacteria in the colon help to digest the remaining food products. 3. The rectum is where faces are stored until they leave the digestive system through the anus as a bowl movement.
How it works
We found that human digestive system is a complex series of organs and glands that processes food. The digestive system is made up of elementary canal (digestive tract) and other organs that play a part in digestion such as liver and pancreas. The elementary canal is of the long tube of organs including esophagus, stomach and intestines- that run from the mouth to anus long about 9 meters (30Feet).
When we eat foods they are not in a form that body can use as nourishment. Food and drink must be changed into smaller molecules of nutrients before they can be absorbed in to the blood and carried to cells throughout the body. Digestion is the organic process by which food is converted into substances that can be absorbed into the body. It is the process by which food and drink are broken down in to their smallest parts so the body can use them to build and nourish cells and to provide energy. Digestion involves mixing of food with digestive juices, moving it through digestive tract and breaking down large molecules of food into smaller molecules. Digestion begins in the mouth when we chew and swallow and completed in the small intestine.
1. Our digestive system is made up of the digestive tract- a series of hollow organs joined in a long, twisting tube from mouth to anus-and other organs that help the body brake down and absorb the food.2. Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, large intestine (colon), rectum and anus. 3. Inside these hollow organs is lining called mucosa. In the mouth stomach and small intestine, the mucosa contains tiny glands that produce juices to help digest food. 4. The digestive tract also contains a layer of smooth muscles that helps break down food and move it along the tract. 5. Two solid digestive organs the liver and pancreas produce digestive juices that reach the intestine through small tubes called ducts. 6. The gall bladder stores the liver’s digestive juice (Bile) until they are needed in the intestine. 7. Parts of the nervous and circulatory systems also play major roles in the digestive system.8. Whatever we eat is ground by the teeth in the mouth. This is the first change in food. The gums in the upper and lower portions of the jaw have a kind of glands or sacks which secrete a thick juice known as saliva in which there is an alkaline matter (ptyalin) which converts starch in to sugar (maltose). Therefore we should chew the food so much that it goes by itself towards throat. 9. Food moves from one organ to the next through muscle action called peristalsis. Peristalsis looks like an ocean wave travelling through the muscle. This wave of narrowing push the food and fluid forward through each hollow organ. The first major muscle movement occurs when food or liquid is swallowed. Although we are able to start swallowing by choice, ones the swallow begins, it becomes involuntary and proceeds under the control of the nerves. 10. Swallowed food is pushed into esophagus, which connects the throat above and with the stomach below. At the junction of esophagus and stomach, there is a ring like muscle, called the lower esophageal sphincter, closing the passage between the two organs. As the food approaches the closed sphincter, the sphincter relaxes and allows the food to pass through to the stomach. 11. Stomach is 13 inches long and 4 inches wide a sack-like, muscular organ that is attached to the esophagus. It can have up to one and a half kilo of food. The stomach has three mechanical tasks. First it stores the swallowed food and liquid. The muscle of the upper part of the stomach relaxes to accept the large volumes of swallowed material. The second job is to mix up the food, liquid and digestive juice produced by the stomach. The lower part of the stomach mixes these materials by its muscle action churning. The third task of stomach is to empty its contents slowly into small intestine. 12. Several factors affect emptying of the stomach, including the kind of food, and the degree of muscle action of the emptying stomach and small intestine. Carbohydrates, for example, spend the least amount of time in the stomach, while the protein stays in the stomach longer, and fat the longest. 13. As the food dissolves into the juices from the pancreas, liver and intestine, the contents of the intestine are mixed and pushed forward to allow further digestion. Finally, the digested nutrients are absorbed through the intestinal walls and transported throughout the body. 14. The waste products of this process include undigested part of the food, known as fiber and older cells that have been shed from the mucosa. These materials are pushed into the colon where they remain until the faces are expelled by a bowl movement.
Production of digestive juices:1. The digestive glands that act first are in the mouth- the salivary glands. The saliva produced by these glands contains an enzyme that begins to digest the starch from food in to smaller molecules. 2. An enzyme is a substance that speeds up the chemical reactions in the body.
3. The next set of digestive glands is in the stomach lining. They produce stomach acid and an enzyme that digests protein into peptone. 4. A thick mucus layer coats the mucosa and helps keep the acidic digestive juice from dissolving the tissue of the stomach itself. In most people, the stomach mucosa is able to resist the juice, although food and other tissues of the body cannot.5. After churning in stomach the food combines with juices forms a sticky paste known as Alm (chime) is released to small intestine where the juices of two other digestive organs mix with the food. 6. One of these organs the pancreas, produces a juice that contains a wide array of enzymes to breakdown the carbohydrates, fat and protein in food. Other enzymes that are active in the process come from the wall of the intestine. 7. The second organ, the liver, produces yet another juice- Bile. Bile is stored between meals in the gall bladder. At meal time, it is squeezed out of gall bladder, through the bile ducts, and into the intestine to mix with the fat in food. The bile acid dissolves fat into the watery contents of the intestine, much like detergents that dissolve grease from frying pan. After fat is dissolved, it is digested by enzymes from the pancreas and the lining of intestine.
Absorption and transport of nutrients:Most digested molecules of food as well as water and minerals are absorbed through small intestine. The mucosa of the small intestine contains many folds that are covered with tiny finger like projections called villi. In turn the villi are covered with microscopic projections called microvilli. These structures create a vast surface area through which nutrients can be absorbed. Specialized cells allow absorbed material to cross the mucosa in to the blood, where they are carried off in the blood stream to other parts of the body for storage or further chemical change. This part of the process varies with different types of nutrients.
Digestion of different food groups
Break down of Carbohydrates: 45 to 65% of the daily calories are achieved from carbohydrates. Foods rich in carbohydrates include bread, potatoes, dried peas and beans, rice, pasta, fruits and vegetables. Many of these foods contain starch and fiber.The digestible carbohydrates-starch and sugar- are broken in to simpler molecules by enzymes in the saliva, in juice produced by pancreas and in the lining of small intestine. Starch is digested in two steps. First an enzyme in the saliva and pancreatic juice breaks the starch in to molecules called maltose. Then an enzyme in the lining of small intestine splits the maltose into glucose molecules that can be absorbed into the blood. Glucose is carried through the blood stream to the liver where it is stored or used to provide energy for the work of the body. Sugars are digested in one step. An enzyme in the lining of small intestine digests sucrose also known as table sugar into glucose and fructose which are absorbed through the intestine into the blood. Milk contains another type of sugar called lactose, which is changed in to absorbable molecules by another enzyme in the intestinal lining. Lactose is a sugar comprising one glucose molecule linked to a galactose molecule; occurs only in milk.Fiber is indigestible and moves through the digestive tract without being broken down by enzymes. Many foods contain both soluble and insoluble fiber. Soluble fiber dissolves easily in water and takes on a soft, gel like texture in the intestine. Insoluble fiber on the other hand passes essentially unchanged through the intestine. Break down of Protein: 15% of the daily calories are achieved from protein. An enzyme in the juice of the stomach starts the digestion of swallowed protein. Pepsin is that enzyme (whose group of compounds that are inactive precursors of enzymes and require some change to become active) released by the chief cells in the stomach and that degrades food proteins into peptides. It is one of the three main proteolytic enzymes in the digestive system. Gastrin is the hormone that triggers the release of pepsinogen and also controls the secretion of hydrochloric acid from the stomach lining. Pepsinogen wants acidic environment which is created by the hydrochloric acid. Upon exposure to hydrochloric acid pepsinogen unfolds and breaks into pepsin. Pepsin’s main function is to break down proteins that are found in protein rich foods. It breaks them into smaller pieces called polypeptides. Interesting thing about pepsin is that it breaks proteins only at certain points so that the protein is not digested completely to the amino acid level. For this to occur, the food needs to pass to the intestines where other enzymes complete the digestion process. Digestion of proteins continues in the duodenum, the first segment of the small intestine. In the small intestine several enzymes in the pancreatic juice and the lining of the intestine complete the breakdown of huge protein molecules in to small molecules called amino acids. As in fat digestion, the pancreas helps the process by secreting the pancreatic protease enzymes trypsin and chymotrypsin. Like pepsin, trypsin breaks down a protein into single amino acid molecules, through a process called hydrolysis. During hydrolysis, a water molecule is inserted between the two amino acids which are bonded together. This breaks the bond between them. These small amino acid molecules can be absorbed through the small intestine in to the blood and then be carried to all parts of the body to build the walls and other parts of the cells. After breakdown, the amino acids are small enough to pass through the intestinal lining into tiny veins (capillaries) in the villi (the finger-like projections on the wall of the small intestine). Once in the bloodstream, the amino acids are distributed by both red blood cells and by the liquid blood plasma to tissues throughout the body where they are used in the creation and repair of cell structures. Break down of Fats: Fat molecules are a rich source of energy for the body. The first step of digestion of fat is to dissolve into the watery contents of the intestine. The bile acids produced by the liver dissolves fat into tiny droplets and allow the pancreatic and intestinal enzymes to break the large fat molecules into smaller ones. Some of these small molecules are fatty acids and cholesterol. The bile acids combine with the fatty acids and cholesterol and help these molecules move into the cells of the mucosa. In these cells the small molecules are formed back in to large ones most of which pass into lymphatic vessels near the intestine. These smaller lymphatic vessels carry the reformed fat into the veins of the chest, and the blood carries the fat to the storage depots in different parts of the body. Although a small amount of lipase is secreted by Ebner's glands on the tongue, and by the stomach, these digestive actions are not significant, as almost no real breakdown of fat occurs until the fats reach the duodenum in the form of gastric chyme. Fat digestion and absorption requires that the complex fat molecules be broken down into smaller more manageable molecules. This is done by mixing the fat with the digestive enzyme lipase, which enters the duodenum from the pancreas - the main source of enzymes for digesting fats and proteins. Lipase chops up lipid molecules into fatty acid molecules and glycerol molecules. However, because fat does not dissolve in water, the fat molecules enter the duodenum in a congealed mass, which makes it impossible for the pancreatic lipase enzymes to attack them, since lipase is a water soluble enzyme and can only attack the surface of the fat molecules. To overcome this problem the digestive system uses a substance called bile, produced in the liver but stored in the gallbladder, which enters the duodenum via the bile duct. Bile emulsifies fats - meaning, it disperses them into small droplets which then become suspended in the watery contents of the digestive tract. Emulsification allows lipase to gain easier access to the fat molecules and thus accelerates their breakdown and digestion.Lipase and other digestive juices break down the fat molecules into fatty acids and types of glycerol. Absorption of fat into the body, which takes 10-15 minutes, occurs in the villi - the millions of finger-like projections which cover the walls of the small intestine. Inside each villus is a series of lymph vessels (lacteals) and blood vessels (capillaries). The lacteals absorb the fatty acids and glycerol into the lymphatic system which eventually drains into the bloodstream. The fatty acids are transported via the bloodstream to the membranes of adipose cells or muscle cells, where they are either stored or oxidized for energy. Since glucose rather than fat is the body's preferred source of energy, and since only about 5 percent of absorbed fat (the glycerols) can be converted into glucose, a significant proportion of digested fat is typically stored as body fat in the adipose cells. The glycerol part is absorbed by the liver and is either converted into glucose (gluconeogenesis), and/or used to help breakdown glucose into energy (glycolysis).
Break down of Vitamins: Another vital part of food that is absorbed through the intestine is vitamins. The vitamins are classified into two by the fluid in which they can be dissolved. 1). Water soluble vitamins, (All the B vitamins and vitamin C), and 2) Fat soluble vitamins (Vitamin A, D, E, & K). Fat soluble vitamins are stored in the liver and fatty tissue of the body, where as water soluble vitamins are not easily stored and excess amounts are flushed out in urine. The availability of vitamins is dependent upon the food eaten, which releases the vitamins in the intestines. Fat-soluble vitamins require fat or lipid micelles as a carrier for transportation in the blood to travel to the liver and other fatty tissues. Water-soluble vitamins are digested and transported into the blood through active-transport channels in the intestine, meaning the concentration of the vitamin allows for channels to open and the vitamin to cross the intestines to a specific protein in the blood. Vitamin B-12 needs a specific transport protein called the intrinsic factor for absorption. The intrinsic factor is a protein produced by the stomach to combine with vitamin B-12 when stomach acid comes in contact with food for digestion. When vitamin B-12 and intrinsic factor reach the small intestines, the pH of the digested food becomes higher, allowing both components to combine and B-12 to become absorbed into your bloodstream.
Break down of Water and Mineral salts: Most of the material absorbed through the small intestine is water in which salt (mineral) is dissolved. The salt and water come from the food and liquid we swallow and the juices secreted by the many digestive organs.
Natural mineral water benefits digestion. Chloride and Bicarbonates are found in mineral water. They can play a role in digestion and assist in keeping acid balanced within the stomach and upper and lower intestines.If you drink something that is de-mineralized, such as distilled waters, you will create an acid pH in your stomach and intestines. You will be prone to have heartburn and aggravate acid reflux. And no, it is not bad for you to drink natural mineral water on an empty stomach. In fact, drinking water on an empty stomach is good for your health.
Hormones & Nerve Regulators
The major hormones that control the functions of the digestive system are produced and released by cells in the mucosa of the stomach and small intestine. These hormones are released in to the blood of the digestive tract, travel back to the heart and through the arteries, return to the digestive system where they stimulate digestive juices and cause organ movement. The main hormones that control digestion are gastrin, secretin, cholecystokinin(CCK)Gastrin: Polypeptide hormone secreted by the mucous lining of the stomach to stimulate production of gastric acid for dissolving and digesting foods; when peptides and amino acids are present in the small intestine. Gastrin is also necessary for the normal cell growth in the lining of the stomach, small intestine and colon.Secretin: A gastrointestinal hormone that stimulates the secretion of water and bicarbonate from the pancreas and bile ducts whenever the stomach empties too much acid into the small intestine. This bicarbonate helps neutralize the acidic stomach contents as they enter the small intestine. Secretin also stimulate the stomach to produce pepsin an enzyme that digests protein and stimulate the liver to produce bile.Cholecystokinin (CCK): A gastrointestinal hormone that stimulates the secretion of pancreatic enzymes and the contraction and emptying of the gall bladder; its release is stimulated by the presence of fatty acids and amino acids in the small intestine. It also promotes normal cell growth of pancreas.
The additional hormones that regulate appetite in the digestive system are Ghrelin and Peptide YY.Ghrelin is produced in the stomach and upper intestine in the absence of food in the digestive system and stimulate appetite.( A gastrointestinal hormone produced by epithelial cells lining the fundus (anatomy) the base of a hollow organ or that part of the organ farthest from its opening) of the stomach; appears to be a stimulant for appetite and feeding, but is also a strong stimulant of growth hormone secretion from the anterior pituitary)Peptide YY is produced in the digestive tract in response to a meal in the system and inhibits appetite.Both of these hormone work on the brain to help regulate the intake of food for energy.
NERVE REGULATORS:Two types of nerves help control the action of the digestive system.Estrinsic, or outside, nerves come to the digestive organs from the brain or spinal cord. They release two chemicals acetylcholine and adrenaline. Acetylcholine causes the muscle layer of the digestive organs to squeeze with more force and increase the push of food and juice through the digestive tract. It also causes the stomach and pancreas to produce more digestive juices. Adrenaline has the opposite effect, it relaxes the muscle of the stomach and intestine and decreases the flow of blood to these organs slowing or stopping digestion.He intrinsic, or inside, nerves make up a very dense network embedded in the walls of the esophagus, stomach, small intestine and colon. The intrinsic nerves are triggered to act when the walls of the hollow organs are stretched by food. These release many substances that speedup or delay the movement of food and production of juices by digestive organs.
In nutshell the complex task of digesting and absorbing nutrients from the foods and liquids we consume each day are controlled together by nerves, hormones, the blood, and the organs of digestive system. Role of Enzymes in NutritionEnzymes are chemical substances produced in the living organism. They are marvellous organic catalysts which are essential to life as they control all the chemical reactions that take place in a living system. Enzymes are part of all living cells, including those of plants and animals. The term enzyme, which literally means in yeast’, was coined following the demonstration of catalytic properties of yeast and yeast juices. Although enzymes are produced in the living cell, they are not dependent upon the vital processes of the cell and work outside the cell. Certain enzymes of yeast, for instance, when expressed from the yeast cells are capable of exerting their usual effect, that is, the conversion of sugar to alcohol. A striking feature of enzymes is that while they enter into chemical reaction, they remain intact in the process. They however, act with maximum efficiency at a certain temperature. Lowering the temperature below or raising it above this level slows the reaction. A high degree of heat, that is above 60 o C, permanently destroys their action. It has been estimated that there are over 20,000 enzymes in the human body. This estimate is based on the number of bodily processes that seem to require action. However, so far only about 1,000 enzymes have been identified. But their great role in nutrition and other living processes has been firmly established. They are protein molecules made up of chains of amino acids. They play a vital role and work more efficiently than any reagent concocted by chemists. Thus for instance, a chemist can separate proteins into their component amino acids by boiling them at 166 o C for over 18 hours in a strong solution of hydrochloric acid, but the enzymes of the small intestines can do so in less than three hours at body temperature in a neutral medium.A feature which distinguishes enzymes from inorganic catalysts is that they are absolutely specific in their actions. This means that a particular enzyme can cause reactions involving only a particular type of substance or a group of closely related substances. The substance on which the enzyme acts is known as "substrate". The specificity of an enzyme is, however, related to the formation of the enzyme-substrate complex which requires that the appropriate groupings of both substrate and enzyme should be in correct relative position. The substrate must fit the enzyme like a key fits its lock.Enzymes which are used in the cells which make them are called intracellular enzymes. Enzymes which are produced in cells which secrete them to other parts of the body are known as extracellular enzymes. Digestive juices are an example of the latter type.NomenclatureThere are few enzymes whose names have been established by long usage such as ptyalin, pepsin, trypsin and erepsin. Apart from these, enzymes are usually named by adding the suffixes to the main part of the name of the substrate upon which they act. Thus amylases act upon starch (amylum), lac- tase acts upon lactose, lipases act upon lipids, maltase acts upon maltose and protesses act upon lipids, maltase acts upon maltose and protesses act upon proteins. There are, however, several enzymes which act upon many substances in different ways. These enzymes are named by their functions rather than substrates. Thus, an enzyme which causes deaminations is called a deaminase and oxidising enzyme an oxidase. Some enzymes work efficiently only if some other specific substance is present in addition to substrate. This other substance is known as an "activator" or a "conenzyme" . "Acti- vators" are usually inorganic ions. They increase the activity of a complete enzyme and may take part in the formation of the enzyme-substrate complex. Many of the conenzymes are related to vitamins. This explains why vitamin deficiencies profoundly alter metabolism. Thus, for instance, thiamine, as thiamine pyrophosphate, functions as a conenzyme in at least 14 enzymes systems. Conenzymes, like enzymes, are being continuously regenerated in the cells. Enzymes play a decisive role in the digestion of food as they are responsible for the chemicalchanges which the food undergoes during digestion. The chemical changes comprise the breaking up of the large molecules of carbohydrates, fats and proteins into smaller ones or conversion of complex substances into simple ones which can be absorbed by the intestines. They also control the numerous reactions by which these simple substances are utilized in the body for building up new tissues and producing energy. The enzymes themselves are not broken down or changed in the process. They remain as powerful at the end of a reaction as they were at the beginning. Moreover, very small amounts can convert large amounts of material. They are thus true catalysts.The process of digestion begins in the mouth. The saliva in the moth, besides helping to masticate the food, carries an enzyme called ptyalin which begins the chemical action of digestion. It initiates the catabolism (breakdown) of carbohydrates by converting starches into simple sugars. This explains the need for thorough mastication of starchy food in the mouth. If this is not done the ptyalin cannot carry out its functions as it is active in an alkaline, neutral or slightly acid medium and is inactivated by the highly acid gastric juices in the stomach. Although enzymatic action starts while food is being chewed, digestion moves into high gear only when the chewed food has passed the esophagus and reached the stomach. While the physical action of peristalsis churns and kneads solid food into a semi-solid amorphous mixture called chyme, this mixture undergoes chemical changes initiated by gastric juices secreted by the walls of the stomach. These juices include mucus for lubricating the stomach, hydrochloric acid and gastric juice. The enzyme or active principle of the gastric juice is pepsin. This enzyme in combination with hydrochloric acid starts the breakdown of proteins into absorbable amino acids called polypeptides. An additional enzyme, rennin, plays an important role in the stomach of the infant. It curdles milk and allows the pepsin to work upon it. The gastric juice has no effect upon starches or fats.When the chyme leaves the stomach and enters the small intestine through the pylorus – the lower escape valve, it still contains much food which is in the form of raw material not yet ready for absorption in the body. Digestion is completed inside the small intestine by several juices. From liver comes a liquid called bile which converts fat globules into a smooth emulsion. The pancreas contributes various enzymes which continue the breakdown of proteins, help to divide starch into sugars and work with bile in digesting fats. The small intestine itself secretes enzymes from its inner wall to complete the reactions. When all the enzymes have done their work, the food is digested and rendered fit for absorption by the system.The following table briefly summarises the chemical digestion of carbohydrates, fats and proteins by various enzymes :Source of Enzyme Enzyme Substrate ProductsMouth- SalivaryGlands- Salivary amylase (ptyalin) Starch Dextrins and maltoseStomach -Gastric protease-Gastric mucosa pepsin Proteins Polypeptidesrennin casein insoluble caseinGastric lipase Short chain &medium chaintriglyceridesFatty acids andglycerolSmall intestine Pancreatic Proteases, trypsinchymotrypsincarboxypeptidasesProteins andpolypeptidesSmaller -polypeptides& amino acidsPanocreatic lipase (steapsin) Fats Mono anddiglycerides, fattyacids and glycerolPancreatic amylase(amylopsin)Amylose &amylopectinMaltose, maltotriose &a-limit dextrinsIntestinal mucosaBrushborderIntestinal peptidasesaminopeptideses dipeptideses