Digestion, salivary

The cephalopods often secrete venom from their posterior salivary glands and hence secretion of venom probably forms part of the process of digestion. Cephalopods include species, such as octopi, capable of injecting various venoms including simple amines such as tetramine. On the other hand, maculotoxin isolated from the octopus H. maculosa was eventually determined to be tetrodotoxin 24 ). 

Diabetic patients have reduced antioxidant defences and suffer from an increased risk of free radical-mediated diseases such as coronary heart disease. EC has a pronounced insulin-like effect on erythrocyte membrane-bound acetylcholinesterase in type II diabetic patients (Rizvi and Zaid, 2001). Tea polyphenols were shown to possess anti-diabetic activity and to be effective both in the prevention and treatment of diabetes (Choi et al, 1998 Yang et al, 1999). The main mechanism by which tea polyphenols appear to lower serum glucose levels is via the inhibition of the activity of the starch digesting enzyme, amylase. Tea inhibits both salivary and intestinal amylase, so that starch is broken down more slowly and the rise in serum glucose is thus reduced. In addition, tea may affect the intestinal absorption of glucose. 

The mouth is the region from the lips to the pharynx. The first step in the digestive process is chewing, or mastication, which is an initial mechanical breakdown of the food that facilitates its movement to the stomach. The mouth is lined with stratified squamous epithelium that provides extra protection from injury by coarse food materials. Three pairs of salivary glands secrete saliva into the oral cavity ... 

Saliva begins the process of chemical digestion with salivary amylase. This enzyme splits starch molecules into fragments. Specifically, polysaccharides, or starches, are broken down into maltose, a disaccharide consisting of two glucose molecules. Salivary amylase may account for up to 75% of starch digestion before it is denatured by gastric acid in the stomach. 

Herbivores that commonly feed on tannin-rich plants have evolved interesting methods to lessen the effect of ingested tannins on their digestive systems. For example, the salivary proteins of rabbits and other rodents are high in the amino acid proline, which has a very high affinity for tannins. Eating food high in tannins stimulates the secretion of these proteins and diminishes the toxic effect of the tannins. 

Enteric bacterial pathogens must maneuver through a lengthy stretch of hazardous terrain before they reach their intended target or infection site within a host. Initially, they must tolerate salivary enzymes having various hydrolytic activities in the mouth, followed by exposure to shedded epithelial cells in the esophagus that may prevent local bacterial adherence (Pearson and Brownlee, 2005). In the stomach, bacteria must endure another severe environment created by the secretion of digestive enzymes and hydrochloric acid (up to 0.1 M concentration and a pH as low as 1.0). Once bacteria reach the intestines, they then encoimter mechanical. 

Sulfation has also been documented in salivary proteins, specifically statherin. The enzymes in saliva are the first wave of the human digestion process and statherin prevents the precipitation of calcium phosphate in the salivary gland and saliva. Since TPST is secreted along with statherin, sulfation plays a role in digestion by binding hydroxylapatite and preventing its precipitation. 

Suppose we start with a starch-rich meal, say one containing a lot of pasta or bread. The digestion of starches begins in the mouth. Saliva contains an enzyme, salivary amylase (aka ptyalin), which catalyzes the conversion of starch to simple sugars such as glucose. This process is completed in the small intestine under the influence of other enzymes in the amylase class. This completes the first phase of carbohydrate catabolism the conversion of complex, polymeric carbohydrates (e.g., starches) to their simple monomeric units, the sugars. 

Dietz, B. A., Hagerman, A. E., and Barrett, G. W. (1994). Role of condensed tannin on salivary tannin-binding proteins, bioenergetics and nitrogen digestibility in Micro-tuspennsylvanicus. Journal of Mammalogy 75,880-889. 

Saliva. The salivary glands produce a slightly alkaline secretion which—in addition to water and salts—contains glycoproteins (mucins) as lubricants, antibodies, and enzymes. a-Amylase attacks polysaccharides, and a lipase hydrolyzes a small proportion of the neutral fats. a-Amylase and lysozyme, a mu-rein-cleaving enzyme (see p. 40), probably serve to regulate the oral bacterial flora rather than for digestion (see p. 340). 

In general, ethanol in low to moderate amounts, is relatively benign to most body systems. A moderate amount of ethanol causes peripheral vasodilation, especially of cutaneous vessels, and stimulates the secretion of salivary and gastric fluids the latter action may aid digestion. On the other hand, ethanol consumption in high concentrations, as found in undiluted spirits, can induce hemorrhagic lesions in the duodenum, inhibit intestinal brush border enzymes, inhibit the uptake of amino acids, and limit the absorption of vitamins and minerals. In addition, ethanol can reduce blood testosterone levels, resulting in sexual dysfunction. 

N.A. Picrasma exeelsa (Sw.) Planch. Quassinoid (quassin), alkaloids, coumarin (scopoletin), vitamin B,.09 Strengthen digestive systems, increase bile flow, secretion of salivary juices, and stomach acid production. 

The principal sites of dietary carbohydrate digestion are the mouth and intestinal lumen. Salivary a-amylase acts on dietary starch (glycogen, amylose, amylopectin), producing oligosaccharides. Pancreatic a-amylase continues the process of starch digestion. 

Digestion of dietary glycogen and starch in the human body begins with the salivary and pancreatic amylases, which cleave a-1,4 linkages at random. It continues with a glucoamylase found in the brush border membranes of the small intestine where it occurs as a complex with maltase.74 Carbohydrases are discussed in Chapter 12, Section B. 

Digestion begins here. Saliva produced by the salivary glands moistens the dry feed so that it is easier to swallow. At this point the feed, if accepted, is swallowed whole. The feed then passes quickly to a pouch in the oesophagus, the crop. 

Studies performed over the years have contributed to better understanding of the interactions between proteins and tannins, which are important not only due to their astringency but also because of their impact on food nutritional characteristics, on human health, and on plant metabolism. It is clear that protein-tannin interactions are influenced by several factors, among which polysaccharides could be important because they are also present in tannin-rich vegetables. Much remains to be studied in this field, particularly the specific phenomenon that occurs between proteins, tannins, and polysaccharides that leads to a decrease in aggregation, and further studies are needed involving other salivary proteins and digestive enzymes. 

The watery component of saliva moistens and lubricates the masticatory process. Salivary mucus helps to bind the food bolus ready for swallowing. The surface coating of mucus also serves to protect the epithelium from potentially harmful substances. Enzymes present in the saliva initiate the digestive process. 

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