Gastric secretion regulation US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Gastric secretion regulation. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Gastric secretion regulation US Medical PG Question 1: A 38-year-old man comes to the clinic complaining of recurrent abdominal pain for the past 2 months. He reports a gnawing, dull pain at the epigastric region that improves with oral ingestion. He has been taking calcium carbonate for the past few weeks; he claims that “it used to help a lot but it’s losing its effects now.” Laboratory testing demonstrated increased gastrin levels after the administration of secretin. A push endoscopy visualized several ulcers at the duodenum and proximal jejunum. What characteristics distinguish the jejunum from the duodenum?
- A. Lack of goblet cells
- B. Crypts of Lieberkuhn
- C. Lack of submucosal Brunner glands (Correct Answer)
- D. Peyer patches
- E. Plicae circulares
Gastric secretion regulation Explanation: ***Lack of submucosal Brunner glands***
- The **jejunum** lacks **Brunner glands**, which are characteristic of the **duodenum** and secrete alkaline mucus to neutralize acidic chyme from the stomach.
- The absence of these glands helps differentiate the jejunum from the duodenum histologically.
*Lack of goblet cells*
- **Goblet cells** are present throughout the small intestine, including both the duodenum and jejunum, though their density increases distally.
- Therefore, the **lack of goblet cells** does not distinguish the jejunum from the duodenum.
*Crypts of Lieberkuhn*
- **Crypts of Lieberkuhn** (intestinal crypts) are present throughout the entire small intestine, including both the **duodenum** and **jejunum**, where they house stem cells for epithelial renewal.
- Their presence is not a distinguishing feature between these two segments histologically.
*Peyer patches*
- **Peyer patches** are lymphoid aggregates primarily found in the **ileum**, not the jejunum or duodenum, and are involved in immune surveillance.
- They are a distinguishing feature of the ileum but not between the jejunum and duodenum.
*Plicae circulares*
- **Plicae circulares** (also known as valves of Kerckring or circular folds) are macroscopic folds of the mucosa and submucosa that are present in both the **duodenum** and **jejunum**.
- They are most prominent in the jejunum, but their mere presence does not distinguish the jejunum from the duodenum.
Gastric secretion regulation US Medical PG Question 2: A scientist is studying the mechanism by which the gastrointestinal system coordinates the process of food digestion. Specifically, she is interested in how distension of the lower esophagus by a bolus of food changes responses in the downstream segments of the digestive system. She observes that there is a resulting relaxation and opening of the lower esophageal (cardiac) sphincter after the introduction of a food bolus. She also observes a simultaneous relaxation of the orad stomach during this time. Which of the following substances is most likely involved in the process being observed here?
- A. Neuropeptide-Y
- B. Secretin
- C. Ghrelin
- D. Vasoactive intestinal polypeptide (Correct Answer)
- E. Motilin
Gastric secretion regulation Explanation: ***Vasoactive intestinal polypeptide***
- **VIP (Vasoactive intestinal polypeptide)** is a neuropeptide that mediates **relaxation** of the **smooth muscle** in the gastrointestinal tract, including the **lower esophageal sphincter** and the **orad stomach**, facilitating the passage of food.
- This relaxation is part of the **receptive relaxation** process, allowing the stomach to accommodate food without a significant increase in intragastric pressure.
*Neuropeptide-Y*
- **Neuropeptide-Y (NPY)** is primarily involved in stimulating **food intake** and **reducing energy expenditure**, acting as an orexigenic peptide.
- It does not directly mediate the relaxation of the **lower esophageal sphincter** or **orad stomach** in response to food bolus distension.
*Secretin*
- **Secretin** is a hormone released in response to **acid in the duodenum** and primarily stimulates the pancreas to release **bicarbonate-rich fluid**.
- Its main role is to neutralize stomach acid, not to mediate sphincter relaxation or stomach accommodation.
*Ghrelin*
- **Ghrelin** is known as the "**hunger hormone**" and primarily stimulates **appetite** and **growth hormone release**.
- It does not play a direct role in the relaxation of the **lower esophageal sphincter** or **orad stomach** during swallowing.
*Motilin*
- **Motilin** promotes **gastric and intestinal motility** during the **interdigestive phase**, responsible for the migrating motor complex (MMC).
- Its actions are generally prokinetic, rather than causing relaxation of the upper GI tract in response to a food bolus.
Gastric secretion regulation US Medical PG Question 3: A 38-year-old man comes to the physician because of an 8-month history of upper abdominal pain. During this period, he has also had nausea, heartburn, and multiple episodes of diarrhea with no blood or mucus. He has smoked one pack of cigarettes daily for the past 18 years. He does not use alcohol or illicit drugs. Current medications include an antacid. The abdomen is soft and there is tenderness to palpation in the epigastric and umbilical areas. Upper endoscopy shows several ulcers in the duodenum and the upper jejunum as well as thick gastric folds. Gastric pH is < 2. Biopsies from the ulcers show no organisms. Which of the following tests is most likely to confirm the diagnosis?
- A. Urea breath test
- B. 24-hour esophageal pH monitoring
- C. Serum vasoactive intestinal polypeptide level
- D. Urine metanephrine levels
- E. Fasting serum gastrin level (Correct Answer)
Gastric secretion regulation Explanation: ***Fasting serum gastrin level***
- The patient's presentation with multiple, refractory **duodenal and jejunal ulcers**, thick gastric folds, and severely low gastric pH (<2) strongly suggests **Zollinger-Ellison syndrome (ZES)**, caused by a gastrin-secreting tumor (gastrinoma).
- Measuring **fasting serum gastrin** is the most direct way to confirm excess gastrin production characteristic of ZES.
*Urea breath test*
- This test is primarily used for diagnosing **Helicobacter pylori infection**, which can cause peptic ulcers.
- However, the presentation of **multiple, refractory ulcers** extending into the jejunum, thick gastric folds, and very low gastric pH are not typical for *H. pylori* alone, and biopsies showed no organisms, making this less likely the primary issue.
*24-hour esophageal pH monitoring*
- This test is used to diagnose **gastroesophageal reflux disease (GERD)** by measuring esophageal acid exposure.
- While heartburn is present, the widespread, severe ulcers in the duodenum and jejunum, along with thick gastric folds and very low gastric pH, point to a more systemic problem of acid hypersecretion rather than just reflux.
*Serum vasoactive intestinal polypeptide level*
- Elevated **VIP (vasoactive intestinal polypeptide) levels** are indicative of a **VIPoma**, a tumor that causes secretory diarrhea.
- While the patient has diarrhea, the prominent features of severe, widespread ulcers and gastric acid hypersecretion are not hallmarks of a VIPoma; they are characteristic of gastrinoma.
*Urine metanephrine levels*
- Measuring **urine metanephrine levels** is used to screen for **pheochromocytoma**, an adrenal tumor that secretes catecholamines.
- Pheochromocytoma symptoms typically include hypertension, palpitations, and headaches, which are not present in this patient's clinical picture of persistent acid-related symptoms and diarrhea.
Gastric secretion regulation US Medical PG Question 4: A 53-year-old patient presents to his primary care provider with a 1-week history of abdominal pain at night and between meals. He has attempted taking antacids, which help briefly, but then the pain returns. The patient has not noticed any changes to the color of his stool but states that he has been having some loose bowel movements. The patient reports that he has had duodenal ulcers in the past and is concerned that this is a recurrence. On exam, his temperature is 98.4°F (36.9°C), blood pressure is 130/84 mmHg, pulse is 64/min, and respirations are 12/min. The abdomen is soft, nontender, and nondistended in clinic today. A fecal occult blood test is positive for blood in the stool. During outpatient workup, H. pylori stool antigen is negative, endoscopy demonstrates duodenal ulcers, and gastrin levels are elevated after a secretin stimulation test. Which of the following should also be examined in this patient?
- A. Parathyroid hormone (Correct Answer)
- B. Plasma metanephrines
- C. Vasoactive intestinal peptide
- D. Calcitonin
- E. Thyroid stimulating hormone
Gastric secretion regulation Explanation: ***Parathyroid hormone***
- Elevated gastrin levels after a secretin stimulation test and recurrent duodenal ulcers are characteristic of **Zollinger-Ellison syndrome (ZES)**, which is often associated with **Multiple Endocrine Neoplasia type 1 (MEN1)**.
- MEN1 involves tumors of the **parathyroid glands**, **pituitary gland**, and **pancreatic islet cells**. Therefore, parathyroid hormone levels should be checked to screen for **primary hyperparathyroidism**, a common component of MEN1.
*Plasma metanephrines*
- **Plasma metanephrines** are used to screen for **pheochromocytoma**, a tumor of the adrenal medulla which is associated with **MEN2**.
- This patient's presentation is consistent with ZES, which is linked to MEN1, not MEN2.
*Vasoactive intestinal peptide*
- **Vasoactive intestinal peptide (VIP)** levels are elevated in **VIPomas**, which cause **watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome)**.
- While VIPomas are pancreatic tumors, the patient's symptoms (abdominal pain, duodenal ulcers, elevated gastrin) point towards ZES, not a VIPoma.
*Calcitonin*
- **Calcitonin** is a marker for **medullary thyroid carcinoma**, which is a component of **MEN2**.
- Given the classic presentation of ZES, screening for MEN1 components is appropriate, not MEN2.
*Thyroid stimulating hormone*
- **Thyroid stimulating hormone (TSH)** is used to assess thyroid function. While thyroid disorders can present with various symptoms, they are not directly linked to ZES or MEN1 in the same way parathyroid disease is.
- There is no specific indication from the patient's symptoms (abdominal pain, ulcers, elevated gastrin) that warrants TSH evaluation as the next step in this context.
Gastric secretion regulation US Medical PG Question 5: During digestion of a high-fat meal, which of the following gastrointestinal hormones primarily stimulates gallbladder contraction?
- A. Secretin
- B. GIP
- C. Gastrin
- D. Cholecystokinin (Correct Answer)
Gastric secretion regulation Explanation: ***Cholecystokinin***
- **Cholecystokinin (CCK)** is released by I-cells in the duodenum and jejunum in response to fats and proteins in the chyme.
- Its primary function related to digestion of fats is to stimulate **gallbladder contraction**, leading to the release of bile for fat emulsification.
*Secretin*
- **Secretin** is released by S-cells in the duodenum in response to acidic chyme from the stomach.
- Its main roles include stimulating the pancreas to release **bicarbonate-rich fluid** to neutralize stomach acid and inhibiting gastric acid secretion.
*GIP*
- **Gastric inhibitory peptide (GIP)**, also known as glucose-dependent insulinotropic polypeptide, is released by K-cells in the duodenum and jejunum.
- It stimulates **insulin secretion** from pancreatic beta cells in response to glucose and fat, and inhibits gastric acid secretion and motility.
*Gastrin*
- **Gastrin** is secreted by G-cells in the stomach antrum and duodenum in response to proteins and vagal stimulation.
- Its main function is to stimulate **gastric acid secretion** by parietal cells and promote gastric motility.
Gastric secretion regulation US Medical PG Question 6: A 33-year-old man comes to the physician because of a 2-month history of burning epigastric pain, dry cough, and occasional regurgitation. The pain is aggravated by eating and lying down. Physical examination shows a soft, non-tender abdomen. Upper endoscopy shows hyperemia in the distal third of the esophagus. Which of the following drugs is most likely to directly inhibit the common pathway of gastric acid secretion?
- A. Pirenzepine
- B. Ranitidine
- C. Lansoprazole (Correct Answer)
- D. Aluminum hydroxide
- E. Octreotide
Gastric secretion regulation Explanation: ***Lansoprazole***
- **Lansoprazole** is a **proton pump inhibitor (PPI)** that irreversibly blocks the **H+/K+-ATPase (proton pump)** in gastric parietal cells, the final common pathway for gastric acid secretion.
- By inhibiting this pump, PPIs effectively reduce acid production, providing significant relief for symptoms like **burning epigastric pain** and **regurgitation** as seen in **gastroesophageal reflux disease (GERD)**.
*Pirenzepine*
- **Pirenzepine** is a **muscarinic M1 receptor antagonist** that selectively inhibits gastric acid secretion stimulated by acetylcholine.
- While it reduces acid, it does not directly target the final common pathway (the proton pump) and is less potent than PPIs.
*Ranitidine*
- **Ranitidine** is an **H2 receptor antagonist** that blocks histamine-mediated acid secretion from parietal cells.
- Although it reduces acid production, it does not inhibit the proton pump directly, which is the common pathway for all acid secretagogues.
*Aluminum hydroxide*
- **Aluminum hydroxide** is an **antacid** that neutralizes existing stomach acid by acting as a buffer.
- It does not inhibit acid secretion but rather works on the acid that has already been secreted.
*Octreotide*
- **Octreotide** is a **somatostatin analog** that inhibits various gastrointestinal hormones, including gastrin, thereby indirectly reducing acid secretion.
- It is primarily used for conditions like **variceal bleeding** or **neuroendocrine tumors** like **gastrinomas**, not for routine GERD treatment.
Gastric secretion regulation US Medical PG Question 7: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?
- A. "Does the diarrhea typically precede the constipation, or vice-versa?"
- B. "Is the diarrhea foul-smelling?"
- C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
- D. "Are the symptoms worse in the morning or at night?"
- E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)
Gastric secretion regulation Explanation: ***Can you tell me more about the symptoms you have been experiencing?***
- This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis.
- In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions.
*Does the diarrhea typically precede the constipation, or vice-versa?*
- While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience.
- It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture.
*Is the diarrhea foul-smelling?*
- Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions.
- However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed.
*Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life*
- Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time.
- However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially.
*Are the symptoms worse in the morning or at night?*
- Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related.
- This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.
Gastric secretion regulation US Medical PG Question 8: A 59-year-old woman comes to the clinic complaining of an intermittent, gnawing epigastric pain for the past 2 months. The pain is exacerbated with food and has been getting progressively worse. The patient denies any weight changes, nausea, vomiting, cough, or dyspepsia. Medical history is significant for chronic back pain for which she takes ibuprofen. Her father passed at the age of 55 due to pancreatic cancer. Labs were unremarkable except for a mild decrease in hemoglobin. What medication is most appropriate to be switched to from the current medication at this time?
- A. Naproxen
- B. Ranitidine
- C. Aspirin
- D. Acetaminophen
- E. Omeprazole (Correct Answer)
Gastric secretion regulation Explanation: ***Omeprazole***
- The patient's symptoms of **gnawing epigastric pain** exacerbated by food, along with a history of chronic ibuprofen use and mild anemia, strongly suggest a **peptic ulcer**.
- **Omeprazole**, a proton pump inhibitor (PPI), is the most effective medication for healing ulcers and preventing their recurrence by reducing gastric acid production.
*Naproxen*
- **Naproxen** is a non-steroidal anti-inflammatory drug (NSAID), similar to ibuprofen, and would likely worsen the patient's symptoms by further inhibiting prostaglandin synthesis necessary for gastric mucosal protection.
- Continuing an NSAID without gastroprotection would increase the risk of ulcer complications, such as bleeding.
*Ranitidine*
- **Ranitidine** is an H2-receptor antagonist, which reduces stomach acid, but it is generally less potent than PPIs like omeprazole for treating and healing ulcers, especially in cases of NSAID-induced gastropathy.
- Its efficacy for advanced or severe peptic ulcer disease is inferior to that of PPIs.
- Note: Ranitidine was withdrawn from the US market in 2020 due to NDMA contamination; alternative H2 blockers include famotidine.
*Aspirin*
- **Aspirin** is an NSAID with significant antiplatelet effects and is well-known to cause and exacerbate peptic ulcers and gastrointestinal bleeding.
- Switching to aspirin would be contraindicated in the presence of strong evidence suggesting active peptic ulcer disease.
*Acetaminophen*
- **Acetaminophen** (paracetamol) is an analgesic that does not have significant anti-inflammatory properties and is not associated with gastric irritation or ulcer formation.
- While it could be used for pain relief, it does not address the underlying issue of peptic ulcer disease or provide gastroprotection, making it an inadequate switch for effective management.
Gastric secretion regulation US Medical PG Question 9: During a study on gastrointestinal hormones, a volunteer is administered the hormone secreted by S cells. Which of the following changes most likely represent the effect of this hormone on gastric and duodenal secretions?
$$$ Gastric H+ %%% Duodenal HCO3- %%% Duodenal Cl- $$$
- A. ↓ ↓ ↓
- B. ↑ ↓ no change
- C. ↑ ↑ ↓
- D. ↓ ↑ ↓ (Correct Answer)
- E. ↓ no change no change
Gastric secretion regulation Explanation: ***↓ ↑ ↓***
- S cells secrete **secretin**, which primarily inhibits **gastric acid (H+) secretion** to protect the duodenal mucosa from acidic chyme.
- Secretin also stimulates the pancreas and bile ducts to secrete **bicarbonate (HCO3-)**, neutralizing the acidic chyme. Duodenal **chloride (Cl-) secretion is typically reduced** as it is often exchanged for bicarbonate or water follows bicarbonate secretion for osmotic balance.
*↓ ↓ ↓*
- While **gastric H+ decreases** due to secretin, **duodenal HCO3- secretion increases**, not decreases, making this option incorrect.
- **Duodenal Cl- secretion** would likely decrease, but the other components are inconsistent with secretin's effects.
*↑ ↓ no change*
- Secretin **inhibits gastric H+ secretion**, so an increase contradicts its primary function to protect the duodenum from acid.
- **Duodenal HCO3- secretion increases**, not decreases, and no change in Cl- is unlikely given the physiological responses to secretin.
*↑ ↑ ↓*
- Secretin **inhibits gastric H+ secretion**, so an increase is incorrect.
- While **duodenal HCO3- increases** and **Cl- decreases**, the initial change in gastric H+ makes this option wrong.
*↓ no change no change*
- While **gastric H+ is indeed decreased**, secretin significantly **increases duodenal HCO3- secretion** and likely decreases duodenal Cl- secretion, making "no change" in these parameters incorrect.
- Secretin has a pronounced effect on both bicarbonate and chloride transport in the duodenum.
Gastric secretion regulation US Medical PG Question 10: A 28-year-old female comes to the emergency department complaining of heart palpitations. She has had multiple episodes of these in the past few months. She has found that if she wears tight clothing then sometimes these episodes will stop spontaneously. On presentation to the ED, she feels like her heart is pounding and reports feeling nauseous. She appears mildly diaphoretic. Her blood pressure is 125/75 mmHg, pulse is 180/min, and respirations are 22/min with an O2 saturation of 99% on room air. A neck maneuver is performed and her pulse returns to 90/min with improvement of her symptoms. Stimulation of afferent fibers from which nerve are most responsible for the resolution of her symptoms?
- A. Facial
- B. Hypoglossal
- C. Glossopharyngeal (Correct Answer)
- D. Trigeminal
- E. Vagus
Gastric secretion regulation Explanation: ***Glossopharyngeal***
- The question specifically asks about **afferent fibers** responsible for the resolution of symptoms during the neck maneuver (carotid sinus massage).
- The **glossopharyngeal nerve (cranial nerve IX)** provides the **afferent (sensory) limb** of the baroreflex by carrying signals from **baroreceptors in the carotid sinus** to the nucleus tractus solitarius in the medulla.
- When the carotid sinus is massaged, baroreceptors are stimulated → afferent signals travel via **CN IX** → medullary cardiovascular centers → efferent vagal output → heart rate slows.
- This is the afferent pathway that initiates the reflex response to terminate **supraventricular tachycardia (SVT)**.
*Vagus*
- The **vagus nerve (cranial nerve X)** is crucial for treating SVT, but it provides the **efferent (motor) limb** of the baroreflex, not the afferent limb.
- After afferent signals from CN IX reach the medulla, the vagus nerve carries parasympathetic output to the SA node to slow the heart rate.
- If the question asked about efferent fibers, vagus would be correct, but it asks specifically about **afferent fibers**.
*Facial*
- The **facial nerve (cranial nerve VII)** primarily controls **facial expressions**, carries taste sensation from the anterior two-thirds of the tongue, and innervates salivary glands.
- It has no role in the baroreflex or cardiac rhythm regulation via neck maneuvers.
*Hypoglossal*
- The **hypoglossal nerve (cranial nerve XII)** is responsible for **tongue movement**.
- It has no involvement in cardiac rhythm regulation or the afferent pathways of the baroreflex.
*Trigeminal*
- The **trigeminal nerve (cranial nerve V)** mediates sensation from the face and controls the muscles of **mastication (chewing)**.
- While trigeminal stimulation via the **diving reflex** (cold water on face) can cause bradycardia, this is not the mechanism involved in carotid sinus massage for SVT treatment.
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