Hormones, stress and behavioural regulation
Introduced| English |
|---|
| HPA axis/ˌeɪtʃ piː ˈeɪ ˈæksɪs/ |
| negative feedback/ˈneɡətɪv ˈfiːdbæk/ |
A decision before an answer
- A hormone is a broadcast message: slow, body-wide, and unreadable by any cell without the receptor.
- Your goal: Trace the HPA stress response from trigger to cortisol.
Run the two clocks
- The stress response runs on two clocks.
- The fast sympathetic-adrenal-medullary path releases adrenaline within seconds; the slower HPA axis runs hypothalamus (CRH) to pituitary (ACTH) to adrenal cortex (cortisol) over minutes, mobilising energy and suppressing non-urgent functions. Chronic stress can affect health through several interacting pathways; cortisol is one part of this regulation, not a single inevitable cause.
The hormone responsible for preparing the uterus for implantation of a fertilised ovum is:
Progesterone builds and maintains the uterine lining.
Match hormone to loop
- Key regulatory hormones: progesterone prepares and maintains the uterine lining for implantation; oxytocin drives labour contractions and milk let-down and is linked to bonding; melatonin times sleep-wake cycles; insulin and glucagon manage blood glucose in opposition.
- Match the hormone to the loop it serves, not to a vague mood label.
Compared with neural signalling, hormonal signalling is:
Hormones travel the bloodstream: slow, sustained, and selective only via receptors.
Compare neural and hormonal
- Hormones differ from neural signals in timing and targeting: neural signalling is often faster and spatially directed; hormonal signalling often acts over longer times through circulation.
- These are tendencies with exceptions, not an absolute division. Only cells carrying the matching receptor respond, so a circulating hormone can still be selective.
A near-miss in traffic: adrenaline within seconds, then cortisol via the HPA axis over minutes; cortisol later inhibits CRH/ACTH to settle the response. Progesterone prepares the uterus for a fertilised ovum. Melatonin rises at night to time sleep.
In the HPA axis, the pituitary releases ACTH, which drives the adrenal cortex to release ____.
CRH from the hypothalamus starts the chain; cortisol is the adrenal output.
Close the feedback loop
- Feedback keeps the system bounded: cortisol inhibits CRH and ACTH release (negative feedback), so the axis ramps down when the stressor passes.
- Feedback failure or chronic activation — not the hormone itself — is what turns an adaptive response into a liability.
Assigning a hormone a single emotion, or forgetting receptor selectivity; hormones broadcast but only receptor-bearing cells answer.
Which answer fits this case?
Trace the HPA stress response from trigger to cortisol
A hormone affects every cell it reaches in the bloodstream.
Only cells with the matching receptor respond; circulation is broad but action is selective.
Keep the distinctions
- HPA axis 下丘脑-垂体-肾上腺轴 — The hypothalamus-pituitary-adrenal chain producing the slower cortisol stress response.
- negative feedback 负反馈 — A product inhibiting its own upstream release, bounding the response.
- Trace the HPA stress response from trigger to cortisol.
- Match key hormones to their regulatory roles.
- Distinguish hormonal from neural timing and targeting.
Match each term with its precise meaning in this lesson.
Keep the distinctions stated in the teaching example.
Put this lesson’s reasoning or event sequence in order.
The order follows the stated process; check each stage before the next.