Hypothalamic and Pituitary Axes and Layered Feedback · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Three levels, one loop

Science · The Human Body · ages 20-22
Name ______________________   Date ____________

  1. How can a responding cell amplify a hormone signal?

    • Every relay molecule removes all hormone from the blood
    • Each hormone molecule grows larger when it binds a receptor
    • One receptor signal activates many relay molecules

  2. Which order follows stimulation in a three-level anterior-pituitary axis?

    • Hypothalamus, anterior pituitary, target gland
    • Target gland, anterior pituitary, hypothalamus
    • Anterior pituitary, target gland, hypothalamus

  3. Cortisol inhibits hormone release at both the hypothalamus and anterior pituitary in the adrenal axis.

    Circle one:   True   False

  4. The adrenal cortex cannot make enough cortisol. The upper levels and feedback still work. Which relative secretion pattern does this model predict?

    • CRH low; ACTH low; cortisol low
    • CRH high; ACTH high; cortisol low
    • CRH high; ACTH low; cortisol high

  5. Which hormone directly stimulates cortisol secretion from the adrenal cortex?

    • CRH released directly by the hypothalamus
    • ACTH released by the anterior pituitary
    • Cortisol released directly by the adrenal cortex

  6. Sustained glucocorticoid treatment produces strong negative feedback. What happens to CRH, ACTH and the adrenal cortex's own cortisol output?

    • CRH rises; ACTH rises; native cortisol falls
    • CRH falls; ACTH rises; native cortisol rises
    • CRH falls; ACTH falls; native cortisol falls

  7. Negative feedback and intracellular signal amplification both increase the adrenal axis's drive.

    Circle one:   True   False

  8. In the lesson's failure model, ACTH and cortisol stay low despite rising CRH. Which level cannot pass on the hypothalamic signal?

    • Anterior pituitary
    • Adrenal cortex alone
    • Hypothalamus alone
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Three levels, one loop W1-mt_tgRAAq3Poe-s1

  1. One receptor signal activates many relay molecules · Receptor activation can start a relay involving many molecules inside the cell. This increases the response without enlarging the hormone.
  2. Hypothalamus, anterior pituitary, target gland · The hypothalamic releasing hormone stimulates the anterior pituitary. Its tropic hormone then stimulates the target gland.
  3. True · Cortisol reduces CRH release from the hypothalamus and ACTH release from the anterior pituitary through negative feedback.
  4. CRH high; ACTH high; cortisol low · Low cortisol reduces feedback inhibition. CRH and ACTH rise, but the failing adrenal cortex cannot restore cortisol production.
  5. ACTH released by the anterior pituitary · ACTH acts directly on the adrenal cortex. CRH acts earlier by stimulating ACTH release from the anterior pituitary.
  6. CRH falls; ACTH falls; native cortisol falls · Drug feedback lowers CRH and ACTH. Reduced ACTH stimulation then lowers the adrenal cortex's own cortisol output.
  7. False · Amplification increases a responding cell's response. Cortisol feedback reduces CRH and ACTH release, limiting further stimulation.
  8. Anterior pituitary · Rising CRH is not followed by adequate ACTH release. The interrupted link is the anterior-pituitary response, leaving the adrenal cortex under-stimulated.
Worksheet · LightMySky