top of page

Describe the fight or flight response and its physiological basis.

Biological Approach

Psychology Essays

 A Level/AS Level/O Level

Free Essay Outline

Briefly introduce the fight or flight response as a physiological and psychological reaction to perceived threats.

Physiological Basis of the Fight or Flight Response
Sympathetic Nervous System Activation: Explain how the sympathetic nervous system is activated in response to a threat, releasing adrenaline and noradrenaline.
Hormonal Changes: Detail the release of adrenaline and noradrenaline from the adrenal glands and their specific effects on the body (e.g., increased heart rate, blood pressure, respiration).
Physiological Responses: Describe the physical changes that occur during the fight or flight response (e.g., pupil dilation, blood flow redirection, digestion suppression).

Purpose and Adaptive Value
Explain how these physiological changes prepare the body to either confront the threat (fight) or escape from it (flight).
Discuss the evolutionary advantage of this response in terms of survival.

Limitations and Modern Relevance
Acknowledge that the fight or flight response is not always adaptive in modern society (e.g., chronic stress).
Briefly mention alternative stress responses such as "freeze" or "tend and befriend."

Summarize the key points about the fight or flight response, its physiological basis, and its significance.

Free Essay

The fight or flight response is an automatic physiological and psychological reaction to a perceived threat or stressor. This innate survival mechanism prepares the body to either confront the danger (fight) or escape to safety (flight). This response involves a complex interplay of neural and hormonal changes that lead to profound physiological effects.

Physiological Basis of the Fight or Flight Response

Sympathetic Nervous System Activation: When a threat is perceived, the amygdala, the brain region responsible for processing emotions, sends a distress signal to the hypothalamus. This triggers the activation of the sympathetic nervous system, a branch of the autonomic nervous system responsible for mobilizing the body's resources in stressful situations.

Hormonal Changes: The sympathetic nervous system stimulates the adrenal glands, located above the kidneys, to release hormones, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine). These hormones act as chemical messengers, traveling through the bloodstream to various organs and systems, initiating a cascade of physiological changes.

Physiological Responses: The release of adrenaline and noradrenaline leads to a wide range of physiological changes aimed at preparing the body for action:

⭐Increased heart rate and blood pressure: These changes ensure increased blood flow, carrying oxygen and glucose to the muscles and brain.
⭐Rapid breathing: Respiration rate and depth increase to maximize oxygen intake.
⭐Blood flow redirection: Blood is redirected away from non-essential functions like digestion and towards muscles and the brain.
⭐Pupil dilation: Pupils widen to increase light intake and enhance visual perception.
⭐Increased blood clotting: This prepares the body for potential injury.
⭐Heightened senses: Hearing and vision become sharper.
⭐Glucose release: The liver releases stored glucose into the bloodstream to provide energy.

Purpose and Adaptive Value

The physiological changes associated with the fight or flight response are all geared towards enhancing survival in dangerous situations. Increased heart rate and respiration provide the body with the necessary energy and oxygen for strenuous physical activity, whether it's fighting off an attacker or fleeing to safety. Blood flow redirection prioritizes essential functions like supplying oxygen to the brain and muscles involved in movement. Heightened senses improve awareness of the environment and potential threats.

From an evolutionary perspective, the fight or flight response provided a significant survival advantage. In environments full of predators and immediate dangers, a quick and effective response to threats was crucial for survival and passing on genes to future generations.

Limitations and Modern Relevance

While the fight or flight response remains crucial for survival, its usefulness in modern society is often limited. In today's world, stressors are often chronic and psychological in nature (e.g., work deadlines, financial worries), rather than immediate physical threats. The constant activation of the fight or flight response under chronic stress can lead to detrimental health consequences, including cardiovascular problems, anxiety disorders, and weakened immune function.

Furthermore, not all responses to threat are limited to fight or flight. More recently, researchers have identified alternative stress responses, such as "freeze" and "tend and befriend." Freezing involves becoming immobile and silent, potentially allowing an individual to avoid detection by a predator. The "tend and befriend" response, more common in females, involves protecting offspring and seeking social support during times of stress. These responses highlight the complexity of stress responses beyond the traditional fight or flight model.


The fight or flight response is a complex physiological and psychological mechanism that has played a crucial role in human survival. Triggered by the perception of threat, it involves the activation of the sympathetic nervous system, hormonal changes (primarily adrenaline and noradrenaline), and a cascade of physiological responses that prepare the body for either confronting or escaping danger. While its evolutionary advantage is undeniable, the fight or flight response is not always adaptive in the context of modern stressors. Recognizing its limitations and exploring alternative stress responses is crucial for understanding and managing stress in today's world.


Sapolsky, R. M. (2004). Why zebras don't get ulcers: The acclaimed guide to stress, stress-related diseases, and coping (3rd ed.). New York: Henry Holt and Company.
Taylor, S. E., Klein, L. C., Lewis, B. P., Gruenewald, T. L., Gurung, R. A., & Updegraff, J. A. (2010). Biobehavioral responses to stress in females: Tend-and-befriend, not fight-or-flight. Psychological Review, 107(3), 411–429.

bottom of page