Nokea
Which of the following is not a component of saliva?
- A. Water
- B. Amylase
- C. Mucus
- D. Hydrochloric acid
Correct Answer: D
Rationale: The correct answer is D: Hydrochloric acid. Saliva is composed mainly of water, amylase (an enzyme that breaks down starch), and mucus. Hydrochloric acid is not a component of saliva; instead, it is a component of gastric juice produced in the stomach. It plays a role in the digestion of food in the stomach by lowering the pH level. Therefore, choice D is the correct answer as it does not belong to the components of saliva. Choices A, B, and C are incorrect as they are all components found in saliva.
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Which of the following mismatches pancreatic enzyme with its function?
- A. Proteolytic -> break down proteins
- B. Amylase -> break down carbohydrates
- C. Nuclease -> breaks down nucleic acids
- D. Pro-carboxypeptidase -> breaks down proteins
Correct Answer: D
Rationale: The correct answer is D because pro-carboxypeptidase is an inactive form of carboxypeptidase, which is involved in breaking down proteins. It is not a mismatch. A is correct as proteolytic enzymes indeed break down proteins. B is correct as amylase breaks down carbohydrates. C is correct as nuclease enzymes break down nucleic acids. Therefore, the mismatch is only seen in option D.
Which of the following is likely to fail to reduce secretion of hydrochloric acid in the stomach:
- A. A H receptor blocker
- B. A nicotinic cholinergic receptor blocker
- C. A muscarinic cholinergic receptor blocker
- D. An inhibitor of the hydrogen-potassium pump
Correct Answer: D
Rationale: The correct answer is D because an inhibitor of the hydrogen-potassium pump directly targets the mechanism responsible for the secretion of hydrochloric acid in the stomach. By inhibiting this pump, the production of acid is reduced.
A H receptor blocker (choice A) and a muscarinic cholinergic receptor blocker (choice C) work by blocking specific receptors involved in stimulating acid secretion. A nicotinic cholinergic receptor blocker (choice B) blocks a different type of receptor that is not directly involved in regulating acid secretion.
In summary, the inhibitor of the hydrogen-potassium pump (choice D) is the most direct and effective way to reduce the secretion of hydrochloric acid in the stomach compared to the other choices.
Which of the following hydrolytic enzymes act in low pH?
- A. Peroxidases
- B. Hydrolases
- C. Amylases
- D. Proteases
Correct Answer: D
Rationale: The correct answer is D: Proteases. Proteases are enzymes that break down proteins, and they are known to function optimally in low pH environments, such as the acidic environment of the stomach. This is because the acidic pH helps in the activation and stability of proteases, allowing them to efficiently break down proteins into smaller peptides and amino acids.
Rationale for why the other choices are incorrect:
A: Peroxidases catalyze oxidation reactions and are not specifically known to act in low pH environments.
B: Hydrolases are a broad category of enzymes that catalyze the hydrolysis of various molecules but are not specifically tailored for low pH conditions.
C: Amylases are enzymes that break down carbohydrates and typically work best in neutral to slightly alkaline pH conditions, not in low pH environments like proteases.
The major secretory product of the colon is
- A. bicarbonate ions.
- B. mucus.
- C. digestive enzymes.
- D. hydrochloric acid.
Correct Answer: B
Rationale: The correct answer is B: mucus. The colon secretes mucus to protect the lining from digestive enzymes and acids, aid in the passage of stool, and maintain proper intestinal function. Bicarbonate ions (A) are secreted in the pancreas to neutralize stomach acid. Digestive enzymes (C) are primarily secreted in the small intestine to break down nutrients. Hydrochloric acid (D) is secreted by the stomach to aid in digestion but not by the colon.
Which one of the following is the correct pathway of bile from the hepatocytes to the gallbladder?
- A. bile canaliculus → hepatic duct → common hepatic duct → common bile duct → gallbladder.
- B. bile canaliculus → hepatic duct → cystic duct → common hepatic duct → gallbladder.
- C. hepatic sinusoid → central vein → hepatic vein → gall bladder.
- D. bile canaliculus → hepatic duct → common hepatic duct → cystic duct → gallbladder.
Correct Answer: D
Rationale: The correct answer is D: bile canaliculus → hepatic duct → common hepatic duct → cystic duct → gallbladder. This pathway reflects the anatomical sequence of bile flow from the smallest bile ducts within the liver (bile canaliculi) to the gallbladder. Bile canaliculi collect bile from hepatocytes, which then flows through larger ducts (hepatic duct, common hepatic duct) before reaching the cystic duct, which connects to the gallbladder for bile storage.
Choices A, B, and C are incorrect because they do not follow the correct anatomical pathway of bile flow. For example, in choice A, the common hepatic duct should connect directly to the cystic duct, not the common bile duct. In choice B, the cystic duct should not connect to the common hepatic duct. In choice C, bile does not flow through the central vein or hepatic vein