Digestion and the Role of Salivary Glands and Stomach L2
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Questions and Answers

What is the main role of salivary glands in digestion?

  • Producing bile for emulsification of fats
  • Absorbing nutrients from food
  • Secreting saliva as a lubricant and containing digestive enzymes (correct)
  • Breaking down proteins into amino acids
  • What is the end product of digestion for carbohydrates?

  • Disaccharides
  • Monosaccharides (correct)
  • Fatty acids & monoacylglycerols
  • Amino acids
  • Which process is NOT a part of the processes of the digestive system?

  • Motility
  • Respiration (correct)
  • Absorption
  • Secretion
  • What are the mechanical effects of digestion mentioned in the text?

    <p>Mastication</p> Signup and view all the answers

    Which gland secretes saliva with an optimum pH of 6.6-7.0?

    <p>Parotid glands</p> Signup and view all the answers

    What do most dietary foodstuffs need to be broken down into for easy absorption?

    <p>Smaller, easily absorbable forms</p> Signup and view all the answers

    What are the end products of digestion for proteins?

    <p>Amino acids</p> Signup and view all the answers

    Which enzyme is present in saliva for breaking down starches?

    <p>Salivary $\alpha$-amylase</p> Signup and view all the answers

    What is the function of lingual lipase in digestion?

    <p>Breaking down fats into fatty acids and glycerol</p> Signup and view all the answers

    Which part of the body secretes bile for emulsification of fats?

    <p>Liver</p> Signup and view all the answers

    What is the primary function of salivary $\text{α}$-amylase in digestion?

    <p>Breaking down starches into simpler sugars</p> Signup and view all the answers

    Which enzyme hydrolyzes α(1,4) glycosidic bonds in starch and glycogen in the mouth?

    <p>Salivary amylase</p> Signup and view all the answers

    What is the result of the action of salivary amylase on starch and glycogen in the mouth?

    <p>Mixture of short oligosaccharides and disaccharides such as maltose and isomaltose</p> Signup and view all the answers

    What pH range inactivates salivary amylase?

    <p>pH 4.0 or less</p> Signup and view all the answers

    Which enzyme forms a milk clot in the stomach?

    <p>Rennin</p> Signup and view all the answers

    What do lingual and gastric lipases hydrolyze in the stomach?

    <p>$ ext{TAG} ightarrow ext{Fatty acids and monoacylglycerols}$</p> Signup and view all the answers

    What is the significance of lingual and gastric lipases in adult humans?

    <p>Low due to lack of emulsification in the duodenum</p> Signup and view all the answers

    Where does significant digestion of carbohydrates occur?

    <p>Small intestine</p> Signup and view all the answers

    Which enzyme denatures proteins in the stomach?

    <p>Pepsin</p> Signup and view all the answers

    What is the role of salivary glands in digestion?

    <p>Secrete salivary amylase for carbohydrate digestion</p> Signup and view all the answers

    In neonates and infants with pancreatic insufficiency, what enzymes are important for lipid digestion?

    <p>Acid-stable lipases such as lingual and gastric lipases</p> Signup and view all the answers

    Where does significant digestion of proteins begin?

    <p>Stomach</p> Signup and view all the answers

    Which enzyme is responsible for the hydrolysis of triacylglycerols (TAG) into fatty acids and monoacylglycerols in the stomach?

    <p>Gastric lipase</p> Signup and view all the answers

    What is the primary reason for the limited role of salivary amylase in digestion?

    <p>Inactivation by the acidic stomach environment</p> Signup and view all the answers

    What is the significance of lingual and gastric lipases in neonates and infants with pancreatic insufficiency?

    <p>They hydrolyze short- or medium-chain fatty acids</p> Signup and view all the answers

    Where does significant digestion of carbohydrates occur?

    <p>Stomach</p> Signup and view all the answers

    What is the end product of lipid digestion by lingual and gastric lipases?

    <p>Free fatty acids and diacylglycerols</p> Signup and view all the answers

    Study Notes

    • Salivary amylase is a 1-4 endoglycosidase that hydrolyzes α(1,4) glycosidic bonds in starch and glycogen in the mouth, resulting in a mixture of short oligosaccharides and disaccharides such as maltose and isomaltose.

    • Salivary amylase cannot hydrolyze disaccharides, α(1,6) glycosidic bonds, or β(1,4) glycosidic bonds of cellulose.

    • Salivary glands secrete salivary amylase, which has a limited role in digestion due to its inactivation by the acidic stomach environment (pH 4.0 or less) and the short time during which it can act on food in the mouth.

    • In addition to salivary amylase, the mouth plays a role in the digestion of carbohydrates, but the significant digestion of carbohydrates occurs in the stomach.

    • The stomach has a low pH environment that denatures proteins, activating pepsin, which cleaves proteins into polypeptides. Rennin, a proteolytic enzyme, forms a milk clot.

    • Digestion of dietary proteins begins in the stomach, and the absence of pepsin and rennin results in impaired digestion of milk proteins in neonates and infants.

    • Lipid digestion begins in the stomach with the action of lingual and gastric lipases, which hydrolyze triacylglycerols (TAG) into fatty acids and monoacylglycerols.

    • Acid-stable lipases, such as lingual and gastric lipases, target substrates that contain short- or medium-chain fatty acids and are important for the digestion of milk fat in neonates and infants with pancreatic insufficiency.

    • The role of lingual and gastric lipases is of little significance in adult humans due to the lack of emulsification, which occurs in the duodenum.

    • The stomach plays a significant role in the digestion of carbohydrates, proteins, and lipids, while the mouth and pancreas contribute to the initiation and continuation of the digestive process.

    • Salivary amylase is a 1-4 endoglycosidase that hydrolyzes α(1,4) glycosidic bonds in starch and glycogen in the mouth, resulting in a mixture of short oligosaccharides and disaccharides such as maltose and isomaltose.

    • Salivary amylase cannot hydrolyze disaccharides, α(1,6) glycosidic bonds, or β(1,4) glycosidic bonds of cellulose.

    • Salivary glands secrete salivary amylase, which has a limited role in digestion due to its inactivation by the acidic stomach environment (pH 4.0 or less) and the short time during which it can act on food in the mouth.

    • In addition to salivary amylase, the mouth plays a role in the digestion of carbohydrates, but the significant digestion of carbohydrates occurs in the stomach.

    • The stomach has a low pH environment that denatures proteins, activating pepsin, which cleaves proteins into polypeptides. Rennin, a proteolytic enzyme, forms a milk clot.

    • Digestion of dietary proteins begins in the stomach, and the absence of pepsin and rennin results in impaired digestion of milk proteins in neonates and infants.

    • Lipid digestion begins in the stomach with the action of lingual and gastric lipases, which hydrolyze triacylglycerols (TAG) into fatty acids and monoacylglycerols.

    • Acid-stable lipases, such as lingual and gastric lipases, target substrates that contain short- or medium-chain fatty acids and are important for the digestion of milk fat in neonates and infants with pancreatic insufficiency.

    • The role of lingual and gastric lipases is of little significance in adult humans due to the lack of emulsification, which occurs in the duodenum.

    • The stomach plays a significant role in the digestion of carbohydrates, proteins, and lipids, while the mouth and pancreas contribute to the initiation and continuation of the digestive process.

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    Description

    Learn about the principle and importance of digesting food, the role of salivary glands, and the role of the stomach in digestion. This quiz covers the mechanical effects of digestion, presented through lecture slides and important doctor's notes.

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