Pancreatic Exocrine Function — MCQs
A 25-year-old obese woman who denies any history of alcohol abuse presents with severe abdominal pain radiating to the back. Laboratory results indicate an increase in serum amylase and lipase, with a marked decrease in calcium. Which of the following likely has caused this condition?
A young boy presents with failure to thrive. Biochemical analysis of a duodenal aspirate after a meal reveals a deficiency of enteropeptidase (enterokinase). Which one of the following digestive enzymes would be affected by this deficiency?
What is the primary effect of GLP-1 on insulin secretion?
Somatostatin is secreted by which type of cells in the pancreas?
Intrinsic factor in the stomach is secreted by:
Monu, a 30-year-old male with a history of chronic alcoholism, presents with sudden onset of epigastric pain that radiates to the back. All are seen except:
Maldigestion of protein and fat is manifested in chronic pancreatitis only if the damage to pancreatic tissue exceeds?
What is the effect of cholecystokinin on the gastrointestinal tract?
Vitamin D absorption is decreased by ?
Enteropeptidase enzyme is secreted by:
Pancreatic Exocrine Function Indian Medical PG Practice Questions and MCQs
Question 1: A 25-year-old obese woman who denies any history of alcohol abuse presents with severe abdominal pain radiating to the back. Laboratory results indicate an increase in serum amylase and lipase, with a marked decrease in calcium. Which of the following likely has caused this condition?
- A. Abetalipoproteinemia
- B. Cholelithiasis (Correct Answer)
- C. Cystic fibrosis
- D. Alcohol
Explanation: **Cholelithiasis** - **Obesity** is a significant risk factor for gallstone formation [2], which can obstruct the pancreatic duct and lead to **pancreatitis** [1]. - The classic presentation of severe abdominal pain radiating to the back, elevated **amylase** and **lipase**, and **hypocalcemia** (due to fat saponification in severe pancreatitis) is highly consistent with pancreatitis secondary to gallstones [1]. *Abetalipoproteinemia* - This is a rare genetic disorder characterized by the inability to synthesize apolipoprotein B, leading to severe **malabsorption** and **neurological deficits**, not pancreatitis. - While it involves lipid abnormalities, it typically presents with steatorrhea, growth failure, and ataxia, not acute abdominal pain. *Cystic fibrosis* - Individuals with **cystic fibrosis** can develop pancreatic insufficiency and chronic pancreatitis due to thick secretions blocking pancreatic ducts, but **acute severe pancreatitis with hypocalcemia** is less typical as an initial presentation in a 25-year-old without a prior diagnosis. - Features like **recurrent respiratory infections** and **failure to thrive** would usually precede or accompany pancreatic issues. *Alcohol* - Although **alcohol abuse** is a very common cause of pancreatitis, the patient explicitly **denies any history of alcohol abuse**, making this etiology less likely in this specific case. - Clinically, alcohol-induced pancreatitis presents similarly, but the absence of positive history rules it out as the primary cause.
Question 2: A young boy presents with failure to thrive. Biochemical analysis of a duodenal aspirate after a meal reveals a deficiency of enteropeptidase (enterokinase). Which one of the following digestive enzymes would be affected by this deficiency?
- A. Amylase
- B. Pepsin
- C. Trypsin (Correct Answer)
- D. Lactase
Explanation: ***Trypsin*** - Enteropeptidase (enterokinase) is crucial for activating **trypsinogen** into its active form, **trypsin**. Without active trypsin, the entire cascade of pancreatic protease activation is disrupted. - Trypsin then activates other pancreatic proteases like chymotrypsin, elastase, and carboxypeptidases, all of which are essential for **protein digestion** in the small intestine. *Amylase* - **Amylase** is a carbohydrate-digesting enzyme, primarily involved in breaking down starch. Its activity is independent of enteropeptidase. - **Pancreatic amylase** is secreted in its active form and does not require proteolytic cleavage by trypsin for activation. *Pepsin* - **Pepsin** is an enzyme found in the stomach that initiates protein digestion. It is activated by **hydrochloric acid** from its inactive precursor, pepsinogen. - Its activity is entirely independent of enteropeptidase, which functions in the duodenum. *Lactase* - **Lactase** is a brush border enzyme located in the small intestine that digests the disaccharide **lactose** into glucose and galactose. - Its production and activity are genetically regulated and not dependent on the protein-digesting enzymes or enteropeptidase.
Question 3: What is the primary effect of GLP-1 on insulin secretion?
- A. Increased aldosterone secretion by adrenal
- B. Increased PTH secretion
- C. Increased insulin secretion from beta-cells of pancreas (Correct Answer)
- D. Increased testosterone secretion from Leydig cells
Explanation: ***Increased insulin secretion from beta-cells of pancreas*** - **Glucagon-like peptide-1 (GLP-1)** is an **incretin hormone** that stimulates **glucose-dependent insulin secretion** from pancreatic beta-cells. - This effect is crucial for maintaining **glucose homeostasis**, especially after a meal. *Increased aldosterone secretion by adrenal* - **Aldosterone secretion** is primarily regulated by the **renin-angiotensin-aldosterone system (RAAS)** and potassium levels, not directly by GLP-1. - Aldosterone's main function is to regulate **sodium and water balance** and **blood pressure**. *Increased PTH secretion* - **Parathyroid hormone (PTH)** secretion is primarily regulated by **serum calcium levels**. - Its main role is to maintain **calcium homeostasis** by affecting bone, kidney, and intestine. *Increased testosterone secretion from Leydig cells* - **Testosterone secretion** from Leydig cells is primarily regulated by **luteinizing hormone (LH)** from the pituitary gland. - GLP-1 has no direct significant role in **gonadal steroidogenesis**.
Question 4: Somatostatin is secreted by which type of cells in the pancreas?
- A. Gamma cells
- B. Delta cells (Correct Answer)
- C. Alpha cells
- D. Beta cells
Explanation: ***Delta cells*** - **Delta cells** (δ-cells) of the pancreatic islets are responsible for secreting **somatostatin**. - Somatostatin acts as a paracrine inhibitor, regulating the secretion of other pancreatic hormones like insulin and glucagon. *Gamma cells* - The term "gamma cells" is not a standard classification for pancreatic islet cells. - Pancreatic islet cells are typically categorized as alpha, beta, delta, and PP (pancreatic polypeptide) cells. *Alpha cells* - **Alpha cells** (α-cells) are responsible for secreting **glucagon**. - Glucagon primarily acts to raise blood glucose levels. *Beta cells* - **Beta cells** (β-cells) are the most abundant pancreatic islet cells and produce **insulin**. - Insulin is crucial for lowering blood glucose by promoting glucose uptake into cells.
Question 5: Intrinsic factor in the stomach is secreted by:
- A. Parietal cells (Correct Answer)
- B. Chief cells
- C. Zymogen cells
- D. Enterochromaffin cells
Explanation: ***Parietal cells*** - **Parietal cells** (also known as oxyntic cells) are responsible for secreting **intrinsic factor** and **hydrochloric acid (HCl)**. - Intrinsic factor is crucial for the absorption of **vitamin B12** in the terminal ileum. *Chief cells* - **Chief cells** primarily secrete **pepsinogen**, the precursor to the proteolytic enzyme pepsin. - They also produce **gastric lipase**, which aids in the digestion of fats. *Zymogen cells* - **Zymogen cells** are another name for **chief cells** in the gastric glands. - They are named for their production of **zymogens**, which are inactive enzyme precursors like pepsinogen. *Enterochromaffin cells* - **Enterochromaffin (EC) cells** are neuroendocrine cells found in the gastrointestinal tract. - They synthesize and secrete **serotonin** and other peptides that regulate gut motility and secretion.
Question 6: Monu, a 30-year-old male with a history of chronic alcoholism, presents with sudden onset of epigastric pain that radiates to the back. All are seen except:
- A. Hypocalcaemia
- B. Increased serum amylase
- C. Low serum lipase (Correct Answer)
- D. Increased LDH
Explanation: ***Low serum lipase*** - In **acute pancreatitis**, serum lipase levels are typically **elevated**, not low, due to the inflammation and damage to pancreatic acinar cells. - A low serum lipase level would indicate a lack of pancreatic enzyme release, which contradicts the classic presentation of acute pancreatitis. *Increased LDH* - **Lactate dehydrogenase (LDH)** can be elevated in **severe acute pancreatitis**, indicating **tissue necrosis** and cell damage. - Elevated LDH is a marker of organ damage and can be used as an indicator of prognosis in acute pancreatitis, particularly in established scoring systems like Ranson's criteria. *Hypocalcaemia* - **Hypocalcaemia** can occur in acute pancreatitis due to the **saponification of peripancreatic fat** by free fatty acids, which binds calcium. - This is a serious complication, and severe hypocalcemia can lead to adverse outcomes like tetany and cardiac arrhythmias. *Increased serum amylase* - **Elevated serum amylase** is a hallmark finding in **acute pancreatitis**, typically rising within hours of onset. - Amylase levels are generally at least **three times the upper limit of normal** to be diagnostic of acute pancreatitis.
Question 7: Maldigestion of protein and fat is manifested in chronic pancreatitis only if the damage to pancreatic tissue exceeds?
- A. 30%
- B. 50%
- C. 90% (Correct Answer)
- D. 75%
Explanation: ***90%*** - **Maldigestion** of protein and fat in chronic pancreatitis typically occurs when there is extensive damage to the pancreatic tissue, specifically affecting more than **90%** of its functional capacity. - This threshold is critical because the pancreas has a significant reserve capacity for enzyme production, meaning a large portion must be damaged before **exocrine insufficiency** becomes clinically apparent. *30%* - Damage to only **30%** of pancreatic tissue is generally below the threshold for significant clinical manifestations of maldigestion. - The remaining **70%** of functional tissue can still adequately produce digestive enzymes to prevent widespread nutrient malabsorption. *50%* - While **50%** damage is substantial, it usually does not lead to overt clinical symptoms of maldigestion, particularly fat malabsorption (**steatorrhea**). - The body's compensatory mechanisms and the remaining functional pancreatic mass can still maintain relatively normal digestion at this stage. *75%* - Although **75%** damage represents significant pancreatic loss, it often does not fully manifest as severe maldigestion of protein and fat. - Significant **steatorrhea** and **protein malabsorption** typically require an even greater reduction in exocrine function.
Question 8: What is the effect of cholecystokinin on the gastrointestinal tract?
- A. Increases gastric acid secretion
- B. Increases gastric motility
- C. Relaxes gall bladder
- D. Increases small intestinal peristalsis (Correct Answer)
Explanation: ***Increases small intestinal peristalsis*** - **Cholecystokinin (CCK)** is released in response to fat and protein in the duodenum and plays a significant role in **digestion and absorption**. - One of its key functions is to enhance **small intestinal motility**, facilitating the mixing and propulsion of chyme for efficient digestion and nutrient absorption. *Increases gastric acid secretion* - **Gastrin** is the primary hormone responsible for increasing **gastric acid secretion**, stimulated by protein and amino acids in the stomach. - While CCK shares structural similarities with gastrin, its predominant effect on gastric acid is typically inhibitory, especially at physiological concentrations, to allow for intestinal processing. *Increases gastric motility* - CCK generally has an **inhibitory effect on gastric emptying and motility**, helping to slow down the rate at which food leaves the stomach. - This allows adequate time for the small intestine to process the incoming chyme, particularly rich in fats, by coordinating with **pancreatic enzyme** and **bile release**. *Relaxes gall bladder* - CCK is known for its potent ability to **contract the gallbladder**, leading to the expulsion of bile into the duodenum. - This action is crucial for **emulsifying dietary fats** and aiding in their digestion and absorption.
Question 9: Vitamin D absorption is decreased by ?
- A. Proteins
- B. Acid
- C. Lactose
- D. Fat malabsorption (Correct Answer)
Explanation: ***Fat malabsorption*** - **Vitamin D** is a **fat-soluble vitamin**, meaning it requires dietary fat for proper absorption in the small intestine. - Conditions causing **fat malabsorption**, such as **cystic fibrosis**, **celiac disease**, or **pancreatic insufficiency**, significantly reduce the uptake of vitamin D. *Proteins* - **Proteins** do not directly decrease vitamin D absorption; in fact, some dietary proteins can enhance vitamin D binding and transport in the bloodstream. - Their primary role is in structural and enzymatic functions, not impeding fat-soluble vitamin uptake. *Acid* - **Gastric acid** is important for the absorption of some nutrients, but it generally does not directly hinder the absorption of **fat-soluble vitamins** like vitamin D. - Conditions like **achlorhydria** primarily affect the absorption of minerals and vitamin B12, rather than vitamin D. *Lactose* - **Lactose** is a sugar found in milk, and its malabsorption (lactose intolerance) primarily causes gastrointestinal symptoms like bloating and diarrhea. - It does not directly interfere with the absorption of **fat-soluble vitamins**; rather, it affects carbohydrate digestion.
Question 10: Enteropeptidase enzyme is secreted by:
- A. Ileum
- B. Duodenum (Correct Answer)
- C. Stomach
- D. Jejunum
Explanation: ***Duodenum*** - **Enteropeptidase** (also known as enterokinase) is a key enzyme primarily secreted by the mucosal cells of the **duodenum**. - Its main function is to activate **trypsinogen** (from the pancreas) into **trypsin**, initiating a cascade of protein digestion. *Ileum* - The ileum is primarily involved in the absorption of **vitamin B12** and **bile salts**. - It does not significantly contribute to the secretion of digestive enzymes like enteropeptidase. *Stomach* - The stomach secretes **pepsin** (to digest proteins) and **hydrochloric acid**, and is involved in initial protein digestion. - It does not produce enteropeptidase, which acts much later in the digestive process. *Jejunum* - The jejunum is a major site for the absorption of **nutrients** like carbohydrates, fats, and proteins. - While it has some brush border enzymes, the primary secretion of enteropeptidase occurs in the duodenum.
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