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Quiz: Stress and the Gut

Test your understanding of Chapter 7. Choose the best answer, then click Show Answer to check.

Question 1

What is the correct order of hormones in the HPA axis?

  1. Cortisol, then ACTH, then CRH
  2. CRH, then ACTH, then cortisol
  3. ACTH, then CRH, then cortisol
  4. Epinephrine, then CRH, then ACTH
Show Answer

The correct answer is B. The hypothalamus releases CRH, which tells the anterior pituitary to release ACTH, which tells the adrenal cortex to make cortisol. Option A reverses the chain; cortisol comes last and then feeds back on the first two steps.

Concept Tested: HPA Axis Bloom's Level: Remember

Question 2

Which part of the body releases ACTH?

  1. The adrenal medulla
  2. The colon lining
  3. The hypothalamus
  4. The anterior pituitary gland
Show Answer

The correct answer is D. ACTH comes from the anterior pituitary and travels in the blood to the adrenal glands. The hypothalamus (C) is one step earlier: it releases CRH, which tells the pituitary to release ACTH.

Concept Tested: ACTH Bloom's Level: Remember

Question 3

What is a mast cell?

  1. An immune cell in tissues, including the gut lining, that stores and quickly releases signals such as histamine and tryptase
  2. A neuron in the hypothalamus that makes CRH
  3. A hormone-making cell in the adrenal cortex
  4. A gut bacterium that produces stress hormones
Show Answer

The correct answer is A. Mast cells sit in tissues like the gut lining and release stored chemicals that can cause inflammation, affect nerves, and loosen the barrier. Option D is a mix-up: mast cells are the body's own immune cells, not microbes.

Concept Tested: Mast Cell Bloom's Level: Remember

Question 4

Why does cortisol usually return to its resting level a few hours after a single stressful event ends?

  1. Cortisol is broken down by gut bacteria as soon as it is made.
  2. The adrenal glands run out of cortisol after one use.
  3. Rising cortisol acts on the hypothalamus and pituitary to reduce CRH and ACTH, a process called negative feedback.
  4. The fight-or-flight response destroys cortisol in the blood.
Show Answer

The correct answer is C. Cortisol turns down the very signals that cause its release, limiting how high and how long the response goes. Option B is a common misconception: the adrenal glands don't "run out"; the system is actively switched off.

Concept Tested: Negative Feedback Bloom's Level: Understand

Question 5

Fight-or-flight generally slows digestion. So why can stress cause urgent diarrhea?

  1. CRH signaling in the brain and colon can speed up colon movement, even while the upper gut is held back.
  2. Stress makes the stomach empty faster, which pushes food straight into the colon.
  3. Diarrhea during stress is imagined; the gut doesn't actually change.
  4. Cortisol directly dissolves stool in the colon.
Show Answer

The correct answer is A. In animals, activating CRF1 receptors in the brain or colon speeds colon movement and causes watery stool, and in a small human study, CRH increased colon movement. Option C is the "all in your head" myth; these are measurable changes in gut function.

Concept Tested: Stress and Gut Motility Bloom's Level: Understand

Question 6

Which statement best explains the difference between acute and chronic stress?

  1. Acute stress is always harmful, and chronic stress is always harmless.
  2. Acute stress involves only cortisol, and chronic stress involves only adrenaline.
  3. Acute stress happens only in adults, and chronic stress only in children.
  4. Acute stress is a short challenge after which the system resets; chronic stress lasts or keeps returning before the system can fully recover.
Show Answer

The correct answer is D. The key difference is duration and repetition. A single race or exam triggers a response that negative feedback can shut down, while ongoing stress keeps reactivating the system. Option A gets it backward: short stress is normal and often useful.

Concept Tested: Chronic Stress Bloom's Level: Understand

Question 7

Riya asks Dr. Alvarez whether the stress of high school caused her Crohn's disease. Based on this chapter, which answer is most accurate?

  1. "Yes, stress is the main known cause of Crohn's disease."
  2. "Stress isn't a known cause of Crohn's, but in people who have IBD, high stress is linked to more flares."
  3. "Stress has no connection at all to IBD symptoms."
  4. "Only stress in early childhood can cause Crohn's disease."
Show Answer

The correct answer is B. NIDDK lists immune, genetic, environmental, and microbial factors, not stress, as possible causes, while a year-long study of 704 people with IBD linked high perceived stress to flares. Option C goes too far in the other direction: stress may affect symptoms even though it isn't a known cause of the disease.

Concept Tested: Stress Response Bloom's Level: Apply

Question 8

In the HPA Axis Stress Dial MicroSim, a student runs one stressful event with feedback on, then again with feedback off. What should she observe the second time?

  1. Cortisol doesn't rise at all.
  2. CRH rises after cortisol instead of before it.
  3. The cortisol peak is higher and it takes longer to return to rest.
  4. The gut panel stops moving completely.
Show Answer

The correct answer is C. Without feedback, nothing actively turns CRH and ACTH down when cortisol rises, so cortisol climbs higher and falls more slowly. Option A is wrong because the stressor still starts the CRH, ACTH, and cortisol chain; feedback controls the shutdown, not the start.

Concept Tested: Cortisol Bloom's Level: Apply

Question 9

Sudo and colleagues (2004) found that germ-free mice had a bigger ACTH and corticosterone response to restraint stress than normal mice. A blog writes, "Germ-free mice prove probiotics lower cortisol in people." What is the strongest analysis of this claim?

  1. The claim is accurate because the study measured cortisol in people.
  2. The claim is accurate because any bacteria lowered the stress response in the study.
  3. The claim is wrong only because the study was too old.
  4. The study was in mice (which make corticosterone, not cortisol), compared no microbes with normal microbes, and found later colonization didn't help, so it can't show what probiotics do in people.
Show Answer

The correct answer is D. The germ-free stress response is a mouse finding about having microbes versus none, with a timing window early in life. Option B is wrong because one harmful E. coli strain actually made the response bigger, so not all bacteria lowered it.

Concept Tested: Germ-Free Stress Response Bloom's Level: Analyze

Question 10

O'Mahony and colleagues (2009) separated rat pups from their mothers for 3 hours a day and found lasting changes in stress hormones, gut sensitivity, and gut microbes. Studies in people link hard early-life experiences with later IBS. Why is the human link weaker evidence of cause than the rat study?

  1. Human studies are observational, so other factors that come with early adversity, like poverty or illness, could explain the link.
  2. Rats have no stress hormones, so the rat study shows nothing.
  3. Human studies always use more people, which makes them less reliable.
  4. Early-life stress has been proven to have no effect in people.
Show Answer

The correct answer is A. In the rat study, researchers assigned the stress and controlled other factors, so it can show cause in rats. Human studies can only observe who had hard early experiences, and many other differences could explain the link. Option D overstates the point: the human link is real as an association, just not proven as cause.

Concept Tested: Early-Life Stress Bloom's Level: Analyze