USMLE PRACTICE QUESTION #54
TOPIC: Physiological homeostasis
Today’s question will test your understanding of the fundamentals of physiological homeostasis.
I’m Paul Ciurysek, MD, and this is The USMLE Times: An independent, subscriber-supported newsletter designed to help you survive medical school, pass your USMLE exams, and match into your dream residency program.
A 45-year-old man visits his primary care physician with a complaint of frequent urination and excessive thirst for the past two months. The patient's medical history is unremarkable, and he denies any recent changes in his diet or exercise habits. His BMI is 29 kg/m². A random blood glucose test reveals a level of 220 mg/dL. The physician initiates further workup to confirm the diagnosis and determine the most appropriate treatment. Which of the following mechanisms best describes the body's attempt to maintain homeostasis in response to its current condition?
A. Increased secretion of insulin
B. Decreased secretion of insulin
C. Increased secretion of glucagon
D. Decreased secretion of glucagon
E. Increased secretion of antidiuretic hormone
F. Decreased secretion of antidiuretic hormone
G. Increased secretion of aldosterone
Detailed Breakdown of Answers + Correct Answer Below ⏬
ANSWER + QUESTION BREAKDOWN
The mental model used to answer this question comes from our detailed test-taking skills masterclass. Here’s how to think through this question:
Step 1. Read the last line to determine what the question is asking: Which physiological mechanism will be employed in an attempt to return to homeostasis?
Step 2: Is this a first-, second-, or third-order question?
Answer: 2nd order: Recognize the problem, then the way to fix it.
Step 3. Read the vignette to gather information.
Step 4. Consider what’s being asked and derive your answer.
Step 5. Look at the answer choices and select the option most closely resembling your thoughts from “Step 4” above.
GENERAL ANALYSIS
This question involves a 45-year-old man presenting with symptoms consistent with hyperglycemia, such as frequent urination and excessive thirst. A random blood glucose test reveals a level of 220 mg/dL, indicating elevated blood sugar. The task is to identify the physiological mechanism the body uses to attempt to maintain homeostasis in response to high blood glucose levels.
ANSWER CHOICES:
ANSWER CHOICE A: Increased secretion of glucose
Explanation: Insulin is a hormone produced by the pancreas that helps lower blood glucose levels by facilitating glucose uptake into cells. In response to high blood glucose levels, the body attempts to secrete more insulin to help reduce the glucose concentration in the blood.
ANSWER CHOICE B: Decreased secretion of glucose
Explanation: A decrease in insulin secretion would lead to higher blood glucose levels.
ANSWER CHOICE C: Increased secretion of glucagon
Explanation: Glucagon raises blood glucose levels by stimulating glycogen breakdown in the liver.
ANSWER CHOICE D: Decreased secretion of glucagon
Explanation: Reducing glucagon secretion can help lower blood glucose levels by decreasing glycogen breakdown. While this could help, it is not the primary response to high blood glucose.
ANSWER CHOICE E: Increased secretion of antidiuretic hormone
Explanation: ADH helps regulate water balance in the body and is, therefore, not directly involved in glucose homeostasis.
ANSWER CHOICE F: Decreased secretion of antidiuretic hormone
Explanation: A decrease in ADH would lead to increased urine output, but it is not a mechanism for controlling blood glucose.
ANSWER CHOICE G: Increased secretion of aldosterone
Explanation: Aldosterone regulates sodium and potassium balance, not glucose levels.
FINAL VERDICT…
In response to elevated blood glucose levels, the body attempts to restore homeostasis primarily by increasing insulin secretion. Insulin facilitates glucose uptake into cells, particularly muscle and adipose tissue, lowering blood glucose levels. This mechanism is crucial for maintaining normal blood glucose concentrations and preventing the complications associated with hyperglycemia. In individuals with type 2 diabetes, insulin resistance may impair this response, but the initial physiological attempt is to increase insulin secretion.
CORRECT ANSWER: A) Increased secretion of insulin
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Thanks for checking out Q54!
See you next time 👋