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The Fight or Flight Response

Core Concept Definition

What is F/F?

The fight or flight response is a rapid, automatic physiological reaction to perceived danger or threat. It prepares the body to either confront the threat (fight) or escape from it (flight). This response is crucial for survival and involves multiple systems working together, notably the nervous and endocrine systems.

Activation Pathways

When a threat is detected, sensory information is sent to the hypothalamus in the brain, which acts as a command centre. The hypothalamus activates two pathways:

1

SYMPATHETIC NERVOUS SYSTEM ACTIVATION

The hypothalamus stimulates the sympathetic branch of the autonomic nervous system. This leads to immediate physiological changes such as increased heart rate, dilation of airways, and diversion of blood flow to muscles. These rapid changes prepare the body for quick action.
2

ACTIVATION OF THE ENDOCRINE SYSTEM

The hypothalamus signals the adrenal medulla (part of the adrenal glands) to release adrenaline (epinephrine) and noradrenaline into the bloodstream.

Role of Adrenaline

Adrenaline is a hormone and neurotransmitter released during stress that triggers enhanced physical ability and mental alertness. Key effects include:

❤️

Heart/BP

Increased heart rate and blood pressure: More oxygen-rich blood reaches muscles and vital organs.
👁️

Pupils

Dilation of pupils: Improves vision to assess the threat.
💨

Airways

Expansion of airways: Allows more oxygen intake.
⚡

Energy

Increased blood glucose: Adrenaline stimulates the liver to release glucose, providing extra energy for muscle activity.
🩸

Blood Flow

Redistribution of blood flow: Blood is diverted away from non-essential systems like digestion towards muscles.

The Homeostasis Formula

Threat Cessation + PNS = Recovery
The body must return to its resting state, conserving energy. The Parasympathetic Nervous System (PNS) is responsible for dampening the fight or flight response.

The Recovery Process (Termination)

✅

Termination: Once the threat passes, the parasympathetic nervous system dampens the fight or flight response. Adrenaline levels fall, heart rate slows down, and the body returns to its resting state, conserving energy and promoting recovery.

Short-Term Necessity vs. Chronic Risk

✅
Essential in Emergencies: The response is crucial for survival, providing instantaneous enhancements to physical capability and alertness.
❌
Harmful Chronic Activation: Chronic activation (due to prolonged stress) can be harmful, contributing to health problems like hypertension, anxiety, and weakened immune function.
Fight or Flight Response Deck
Term
Fight or Flight Response

What is the fight or flight response?

Answer
Definition

A rapid, automatic physiological reaction to perceived danger, preparing the body to fight or flee.

Term
Command Center

Which brain area acts as the command center in the fight or flight response?

Answer
The Hypothalamus

The hypothalamus.

Term
Nervous System Branch

Which nervous system branch is activated in the fight or flight response?

Answer
Sympathetic Nervous System

The sympathetic nervous system.

Term
Hormones Released

What hormones are released during the fight or flight response?

Answer
Adrenaline & Noradrenaline

Adrenaline (epinephrine) and noradrenaline.

Term
Physiological Changes

Name two physiological changes caused by adrenaline.

Answer
Heart Rate & Airway Dilation

Increased heart rate and dilation of airways.

Term
Blood Glucose

How does adrenaline affect blood glucose levels?

Answer
Glucose Release

It stimulates the liver to release glucose for extra energy.

Term
Response Dampening

What system dampens the fight or flight response after the threat passes?

Answer
Parasympathetic Nervous System

The parasympathetic nervous system.

Term
Health Risks

What are possible health risks of chronic fight or flight activation?

Answer
Hypertension, Anxiety, Immune Weakening

Hypertension, anxiety, and weakened immune function.

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🧠 Fight or Flight Response Quiz

1. What part of the brain initiates the fight or flight response?

The hypothalamus processes sensory threats and triggers the response.

2. Which hormone is primarily released by the adrenal medulla during fight or flight?

Adrenaline prepares the body for rapid action during stress.

3. True or False: The parasympathetic nervous system activates the fight or flight response.

The sympathetic nervous system activates it; the parasympathetic system helps return the body to rest afterward.

4. Which of the following is NOT a typical physiological effect of the fight or flight response?

Pupils dilate to improve vision during threat, not constrict.

5. Prolonged activation of the fight or flight response may lead to:

Chronic stress can cause health problems including hypertension.

📊 Results

  • Notes and Quiz
  • Psychology
  • AS & A Level
  • Stress
  • AQA