26 Questions
What is the purpose of hydrochloric acid in gastric juice during protein digestion?
Kills some bacteria and denatures proteins
What is the role of pepsin in protein digestion?
Hydrolyzes denatured proteins into smaller peptides
Why are dietary proteins too large to be absorbed by the intestine?
They must be hydrolyzed to their constituent amino acids for absorption
Which organ is responsible for secreting pepsinogen, the inactive zymogen of pepsin?
Stomach
What activates pepsinogen to form active pepsin in the stomach?
HCl and pepsin
What is the main function of acid-stable endopeptidase in gastric juice?
Hydrolysis of peptide bonds within proteins
Which enzyme is responsible for cleaving oligopeptides into free amino acids and smaller peptides in the small intestine?
Enteropeptidase
What is the problematic fraction of gluten that can cause immune damage to the small intestine's villi in individuals with celiac disease?
Gliadin
Which hormone stimulates the release of a watery solution rich in bicarbonate for neutralizing pH in the duodenum?
Secretin
Which disease can lead to abnormalities in the transport of cystine and dibasic amino acids, potentially causing kidney stones?
Cystinuria
Which enzyme hydrolyzes carbohydrates with α-1,4 and α-1,6 bonds, and is found in salivary and pancreatic secretions?
\alpha-amylase
What happens to cellulose due to the lack of a specific enzyme in the human body?
It is not absorbed by the body
Where does the digestion of disaccharides into monosaccharides take place?
Duodenum and upper jejunum
What enzyme continues the process of carbohydrate digestion in the small intestine?
Pancreatic α-amylase
Which enzyme is responsible for breaking down lactose?
Lactase
What can abnormal levels of serum α-amylase indicate?
Acute pancreatitis
Which hormone regulates the secretion of digestive enzymes?
Cholecystokinin
What is the clinical consequence of lactose intolerance?
Malabsorption of lactose
Which of the following enzymes convert trypsinogen to trypsin?
Trypsin
What is the normal serum level of a-amylases?
30
Which of the following enzymes is deficient in an infant with diarrhea and abdominal distention after breastfeeding?
Lactase
What are some effects of Cholecystokinin (CCK)?
All of the above
What amino acids transport is affected in cystinuria?
$Cystine$, $Ornithine$, $Lysine$, $Arginine$
What is the source of proteolytic enzymes?
All of the above
What converts trypsinogen to trypsin?
Trypsin
What enzyme stimulates the release of pancreatic digestive enzymes?
CCK (Cholecystokinin)
Study Notes
- Substrate for intestinal disaccharidases: Disaccharides like isomaltose, maltose, sucrose, and lactose
- Intestinal disaccharidases' location and enzymes: 1) Isomaltase and α(1,6) glucosidase at the jejunum mucosal lining, 2) Maltase and sucrose at the brush border membranes of the intestinal mucosal cells
- Starch and glycogen hydrolysis: α-amylase hydrolyzes α(1,4) glycosidic bonds in starch and glycogen, producing a mixture of short oligosaccharides and disaccharides (maltose and isomaltose)
- No carbohydrate digestion occurs in the stomach due to its acidic environment, which inactivates salivary α-amylase
- Pancreatic α-amylase continues the process of carbohydrate digestion in the small intestine
- Clinical significance of α-amylase: Abnormal levels in serum can indicate acute pancreatitis
- Digestion of carbohydrates in the small intestine: 1) Disaccharidases break down disaccharides into monosaccharides, 2) Monosaccharides are absorbed by the intestinal mucosal cells in the duodenum and upper jejunum using specific transporters (GLUTs)
- Lactose intolerance: Caused by lactase deficiency, undigested lactose in the large intestine leads to osmotic diarrhea, abdominal cramps, and flatulence due to bacterial fermentation
- Protein digestion: Produced by the stomach, pancreas, and small intestine, enzymes like HCL and Pepsin in the stomach, pancreatic zymogens (trypsinogen, chymotrypsinogen, elastase, and carboxypeptidases), and intestinal aminopeptidase complete the digestion and absorption process intracellularly
- Hormonal control: Hormones like cholecystokinin and secretin regulate the digestion and secretion of digestive enzymes
- Cellulose digestion: Cannot be digested due to the absence of an enzyme that can hydrolyze the β(1-4) bonds, but it has several beneficial effects
These bullet points provide a detailed summary of the key facts, figures, and entities discussed in the text, making it easier to understand the complex topic of carbohydrate digestion and absorption in humans.
Test your knowledge of carbohydrate digestion and enzymes with this quiz. Explore topics such as the substrates, locations, and products of key digestive enzymes involved in breaking down carbohydrates.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
