Describe the three Core fight-or-flight effects of adrenaline
Connect adrenal secretion with increased breathing rate, heart rate and pupil diameter.
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Recall electrical impulses, blood transport, gland secretion and the distinction between a stimulus and a body response.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which hormone is secreted in the supplied fight-or-flight situation?
What you will learn
- Follow the fight-or-flight signal
- State all three required response directions
Describe the three Core fight-or-flight effects of adrenaline
| Feature | Meaning |
|---|---|
| Signal | Adrenaline from adrenal glands |
| Breathing | Rate increases |
| Heart | Rate increases |
| Pupil | Diameter increases |
Follow the fight-or-flight signal
Adrenaline is secreted in fight-or-flight situations, when the body prepares for a rapid response to a challenge or threat. Adrenal glands release the chemical hormone into the blood, which carries it to responsive targets. The Core description asks for the hormone and its three stated effects rather than a full account of every stress pathway.
Breathing rate increases: more breaths are taken per unit time. Heart rate increases: the heart beats more often per unit time. Pupil diameter increases: the opening through which light enters becomes wider. These are three distinct quantities; breathing rate is not automatically the same as breathing depth, and heart rate is not the volume pumped in each beat.
State all three required response directions
The changes support readiness for action. Faster breathing can support gas exchange, and a faster heart can increase the frequency of pumping. A larger pupil admits more light under comparable conditions. The exact change in an individual depends on context, so the teaching model gives directions rather than a guaranteed numerical value for every situation.
The pupil also responds to changes in light intensity through the pupil reflex studied earlier. Adrenaline during fight or flight and increased brightness are different inputs. A question that supplies fight or flight asks for increased pupil diameter in this account; a brightness-only pupil question asks for constriction. Neither account supplies a universal pupil size under every combination of inputs.
Sources for this lesson
Pause and explain
Which list contains all three Core effects?
Worked example
State the three required Core adrenaline effects.
Show the worked solution
- Breathing rate and heart rate both increase.
- Pupil diameter also increases.
Answer Increased breathing rate, increased heart rate and increased pupil diameter.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Name the fight-or-flight hormone and describe all three Core effects.
Give me a hint
Give the chemical name and three increase directions.
Compare my reasoning
- Adrenaline is secreted.
- Breathing rate, heart rate and pupil diameter increase.
Adrenaline: increased breathing rate, increased heart rate and increased pupil diameter.
Look for these in your work
- Name adrenaline
- Include all three effects
Explain the distinction between increased breathing rate and increased heart rate.
Give me a hint
Define what is counted per unit time.
Compare my reasoning
- Breathing rate counts breaths per unit time.
- Heart rate counts heart beats per unit time.
Breathing rate is breaths per unit time; heart rate is heart beats per unit time. Both increase in the required adrenaline account.
Look for these in your work
- Define both rate quantities
- Give both response directions
A learner gives pupil constriction in a supplied fight-or-flight answer because bright light can cause constriction. Correct the answer and distinguish the contexts.
Give me a hint
Different supplied stimuli require different accounts.
Compare my reasoning
- Adrenaline fight or flight is described with increased pupil diameter.
- Increased brightness alone triggers a constricting pupil reflex.
For the supplied fight-or-flight account, pupil diameter increases. Brightness-induced constriction describes a different input and does not replace this required adrenaline effect.
Look for these in your work
- Correct the fight-or-flight direction
- Distinguish the light-reflex context
Common mistakes
- Giving decreased pupil diameter for the supplied fight-or-flight account.
- Replacing breathing rate with depth without answering rate.
What can you explain now?
Which list contains all three Core effects?
Compare with the explanation
Breathing rate, heart rate and pupil diameter increase
All three quantities and directions are specified.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
State adrenaline and all three Core effects with the correct directions.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.