Digestion of Foods

In stage 1 of catabolism, foods undergo digestion, a process that converts large molecnles to smaller ones that can be absorbed by the body. 

Carbohydrates begin digestion in the mouth, lipids in the small intestine, and proteins in the stomach and small intestine. 

Obtain a cracker or small piece of bread and chew it for 4 to 5 min. During that time, observe any change in the taste. 

Some mUk products contain Lac-taid, which is the lactase that catalyzes the digestion of lactose. Look for the brands of milk and ice cream that contain Lactaid or lactase enzyme. 

FIGURE 18.3 In stage 1 of metabolism, the digestion of carbohydrates begins in the mouth and is completed in the small intestine. 

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Candidate protease inhibitor drugs must be relatively specific for the HIV-1 protease. Many other aspartic proteases exist in the human body and are essential to a variety of body functions, including digestion of food and processing of hormones. An ideal drug thus must strongly inhibit the HIV-1 protease, must be delivered effectively to the lymphocytes where the protease must be blocked, and should not adversely affect the activities of the essential human aspartic proteases. 

Bile acids, which exist mainly as bile salts, are polar carboxylic acid derivatives of cholesterol that are important in the digestion of food, especially the solubilization of ingested fats. The Na and salts of glycocholic acid and tauro-cholic acid are the principal bile salts (Ligure 25.41). Glycocholate and tauro-cholate are conjugates of cholic acid with glycine and taurine, respectively. 

What chemical events occur during the digestion of food ... 

The nervous system is a complex part of the human body concerned with die regulation and coordination of body activities such as movement, digestion of food, sleep, and elimination of waste products. The nervous system has two main divisions the central nervous system (CNS) and the peripheral nervous system (PNS). Figure 22-1 illustrates the divisions of die nervous system. 

The enzymes pancreatin and pancrelipase, which are manufactured and secreted by the pancreas, are responsible for the breakdown of fats, starches, and proteins. These enzymes are necessary for the breakdown and digestion of food. Both enzymes are available as oral supplements. 

This energy has to be provided by a chemical process the digestion of food. 

The growth of a child, the production of polymers from petroleum, and the digestion of food are all the outcome of chemical reactions, processes by which one or more substances are converted into other substances. This type of process is a chemical change. The starting materials are called the reactants and the substances formed are called the products. The chemicals available in a laboratory are called reagents. In this section, we see how to use the symbolic language of chemistry to describe chemical reactions. 

As described in Section 4-1. one important class of chemical reactions involves transfers of protons between chemical species. An equally important class of chemical reactions involves transfers of electrons between chemical species. These are oxidation-reduction reactions. Commonplace examples of oxidation-reduction reactions include the msting of iron, the digestion of food, and the burning of gasoline. Paper manufacture, the subject of our Box, employs oxidation-reduction chemishy to bleach wood pulp. All metals used in the chemical industry and manufacturing are extracted and purified through oxidation-reduction chemistry, and many biochemical pathways involve the transfer of electrons from one substance to another. 

A novel TLC spectrofluorometric method for identification and determination of selenium in different food samples of animal and vegetable origin has been proposed [30]. The procedure involves the digestion of food sample (1 to 5 g) in the presence of cone. HNO3 (5 ml), 70% HCIO4 (10 ml), and FIjO (10 ml) in a 250-ml Kjeldahl flask reduction of Se(VI) into Se(IV) complexation of the isolated selenium with 23-diaminonaphthene (DAN) extraction of the resultant Se—DAN complex with cyclohexane and spectrofluorometric determination followed by confirmation of the presence of Se in the sample by TLC using thin layers of MN-300 cellulose powder. 

The pancreas is an exocrine gland and an endocrine gland. The exocrine tissue produces a bicarbonate solution and digestive enzymes. These substances are transported to the small intestine where they play a role in the chemical digestion of food. These functions are fully discussed in Chapter 18 on the digestive system. 

Fu, T.J., Abbott, U. And Hatzos, C., Digestibility of food allergens and non-allergenic proteins in simulated gastric and intestinal fluids — a comparative study. J. Agric. Food Chem., 50, 7154, 2002. 

The absence of influence on digestion and metabolism of nutrients of the food ration The digestion of food nutrients depends on their correlation in the ration. The use of the given amino acid, for example, arginin or taurin in the concentrations of treatment diminishes the digestion of other amino acids. 

Because digestion of food in the intestinal tract is dispensable and only counterproductive, the propulsion of intestinal contents is slowed to the extent that peristalsis diminishes and sphinc-teric tonus increases. However, in order to increase nutrient supply to heart and musculature, glucose from the liver and free fatty acid from adipose tissue must be released into the blood. The bronchi are dilated, enabling tidal volume and alveolar oxygen uptake to be increased. 

Blaxter, K.L., Graham, N.Mc. and Wainman, F.W. (1956) Some observations on the digestibility of food by sheep and on related problems. British Journal of Nutrition 10, 59-91. 

Figure 5-4. Metabolic activities of major organs in the fed state. The relative activities of major metabolic pathways or processes in each of the organs are indicated by their font sizes. The exchange of nutrient materials and fuel molecules through the bloodstream illustrates the interrelationships of these organs. In the absorptive condition, all organs share the bounty of nutrients made available by digestion of food by the intestine. PPP, pentose phosphate pathway FA, fatty acids TAG, triacyl-glycerol.

Imagine a lizard waking in the morning and stretching out on a warm rock to absorb the heat and raise body temperature to the ideal for action. Later in the day, observe the snake, which like the lizard has warmed itself in the morning, has hunted successfully, and has now produced excess body heat from exercise and the digestion of food. To get rid of the... 

Without insuiin, giucose produced by the digestion of food remains in the biood and is excreted from the body by the kidneys. This is what happens in peopie with untreated diabetes. Not everyone who has diabetes suffers from a shortage of insuiin. Sometimes the body produces enough insuiin, but the ceiis have become insensitive to it, causing the giucose to remain in the biood. Obesity and iack of exercise are two factors that can contribute to the occurrence of diabetes. 

In elderly people, the Qi, blood and essence are no longer strong, the movement of Qi and the circulation of blood are not smooth, the digestion of food and the metabolism of water become slow, and the mood is often unstable. Consequently, herbs should be prescribed with extra care. 

Finally, it is clear that much more research needs to be performed to connect the disciplines of colloid science and nutrition, especially in the application areas of functional foods and delivery systems. The combination of information from both in vitro and in vivo studies is evidently required in order to be able to understand properly the complex physicochemical processes that can occur during the digestion of food colloids. Our ultimate objective must be to make use of this knowledge to produce effective strategies for the formulation of a healthier diet with optimized bioavailability of the most desirable ingredients. 

Enzymes are proteins that act as catalysts for reactions in the body, including the digestion of food. 

BILE. A biller alkaline fluid secreted by the liver inLo llie duodenum, which aids in the digestion of food. The chief components of bile are bile salts and bile pigments. Because of its strong alkalinity, bile neutralizes the acid coming into the duodenum from the stomach. The bile not only performs important functions in the process of digestion, but also serves as a vehicle for the excretion of waste products from the body. 

These agents are administered to aid in the digestion of food. The primary digestant preparations contain pancreatic enzymes or bile salts. Pancreatic enzymes such as amylase, trypsin, and lipase are responsible for digestion of carbohydrates, proteins, and lipids, respectively. These enzymes are normally synthesized in the pancreas and secreted into the duodenum via the pancreatic duct. Bile salts are synthesized in the liver, stored in the gallbladder, and released into the duodenum via the common bile duct. Bile salts serve to emulsify lipids in the intestinal tract and are important in lipid digestion and absorption. 

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