The fight or flight response is an automatic physiological reaction to a perceived threat, in which the sympathetic nervous system and endocrine system flood the body with adrenaline and cortisol to prepare it to either confront the danger or escape it.
The fight or flight response is your body's built-in alarm system. When you perceive a threat, your nervous system and endocrine system fire off automatically, no conscious decision required. Your heart rate spikes, breathing speeds up, pupils dilate, and blood rushes to your muscles. All of this gets you ready to either stand and fight or run away.
Two systems do the heavy lifting here. The sympathetic nervous system triggers the fast electrical response, and the endocrine system releases hormones like adrenaline and cortisol that keep the body revved up. Think of the sympathetic nervous system as the light switch that flips on instantly, while the endocrine system is the dimmer that holds the lights on a bit longer. Once the threat passes, the body works to return to homeostasis, its balanced resting state.
This term lives in two places, which is exactly why it's worth knowing well. In Unit 2, it connects to Topic 2.2 (The Endocrine System), where you trace how glands and hormones drive behavior. In the stress and coping material (Topic 7.4), it's the classic example of how the body physically reacts to stressors. The same concept threads through cognition too, since how you appraise a situation (a learning objective like AP Psych Revised 2.2.A about judgment and decision-making) determines whether your brain decides something is a threat in the first place. The big takeaway the exam rewards is recognizing that biology and psychology aren't separate, your thoughts can trigger a full-body physiological cascade.
Keep studying AP Psychology Unit 7
Sympathetic Nervous System (Unit 2)
This is the actual machinery behind fight or flight. The sympathetic nervous system is the gas pedal that triggers the reaction, while its partner, the parasympathetic nervous system, is the brake that calms you back down afterward.
Adrenaline and Cortisol (Unit 2)
These are the chemical messengers that make the response last. Adrenaline gives you the instant surge of energy, and cortisol keeps stress hormones elevated, which is why one practice item asks how cortisol shapes your response to stress.
Stress and Coping (Unit 7)
Topic 7.4 zooms out from the biology to the bigger picture. Fight or flight is the body's short-term answer to a stressor, but chronic activation is what makes long-term stress harmful, which links straight to coping strategies.
Homeostasis (Unit 2)
Fight or flight pulls your body out of balance on purpose. Homeostasis is the goal your body returns to once the threat is gone, so the two are essentially opposite ends of the same regulation cycle.
On multiple choice, expect stems that describe a person facing a sudden threat and ask which system or hormone is responsible. The right answer is usually the sympathetic nervous system or adrenaline, not the parasympathetic system. Practice questions also push the endocrine angle, asking how cortisol influences a stress response or how a leader who repeatedly triggers employees' sympathetic responses might hurt team performance. No released FRQ has used this exact term, but it's a natural fit for any prompt that asks you to apply a biological or stress concept to a scenario. If a free-response question asks how the body reacts to a stressor, naming the sympathetic nervous system, adrenaline, and the fight or flight response together is a clean way to earn the point.
Fight or flight is the sympathetic nervous system speeding everything up to handle a threat. The parasympathetic nervous system does the opposite, slowing your heart rate and calming you down once the danger passes. If a question describes someone relaxing after a scare, that's the parasympathetic system, not fight or flight.
Fight or flight is an automatic physiological response to a perceived threat, not a conscious choice you make.
The sympathetic nervous system triggers the fast response while the endocrine system releases adrenaline and cortisol to sustain it.
After the threat passes, the parasympathetic nervous system helps return your body to homeostasis.
This concept appears in both Unit 2 (the endocrine system) and the stress and coping material, so it bridges biology and stress.
Chronic activation of this response is harmful, which is why it connects to long-term stress and coping in Unit 7.
It's your body's automatic reaction to a perceived threat, driven by the sympathetic nervous system and the release of adrenaline and cortisol. Your body prepares to either confront the danger (fight) or escape it (flight).
Sympathetic. The sympathetic nervous system speeds your body up for fight or flight, while the parasympathetic nervous system calms you back down (rest and digest) after the threat is gone.
No. The whole point is that the response is automatic and physiological, kicking in before you consciously think about it. Your appraisal of a situation can trigger it, but the bodily reaction itself isn't a deliberate decision.
Adrenaline (also called epinephrine) gives you the instant energy surge, and cortisol keeps stress hormones elevated. Both come from the endocrine system, which is why this term shows up in Topic 2.2.
Yes. It's tested on multiple choice through scenario stems about the sympathetic nervous system, adrenaline, and cortisol, and it's a strong concept to apply on any free-response prompt about how the body reacts to stress.
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