Fight or Flight Response (Adrenaline)

This section explores Fight or Flight Response, focusing on the role of adrenaline within the Biopsychology module of psychology. The fight or flight response is an automatic physiological reaction to a perceived threat. It evolved as a survival mechanism that prepares an individual to face danger (fight) or flee to safety (flight). This response is critical for enabling a person to react quickly in life-threatening situations. The sympathetic nervous system and the endocrine system work together to activate this response, with adrenaline playing a key role.

Biopsychology: The Fight or Flight Response and the Role of Adrenaline

The Process of the Fight or Flight Response

Detection of a Threat

The fight or flight response is initiated when a potential threat is detected by the brain, particularly by the amygdala, which is involved in processing emotional responses.

The amygdala sends a distress signal to the hypothalamus, which acts as a command centre for initiating the body’s response to stress.

Activation of the Sympathetic Nervous System

The hypothalamus activates the sympathetic branch of the autonomic nervous system (ANS). This branch is responsible for preparing the body to respond rapidly to danger.

Signals are sent from the hypothalamus to the adrenal medulla, which is part of the adrenal glands located just above the kidneys.

Release of Adrenaline

The adrenal medulla responds by releasing adrenaline (also known as epinephrine) into the bloodstream.

Adrenaline, a key hormone in the fight or flight response, has widespread effects on the body, enabling it to act quickly and effectively in response to the threat.

Physiological Effects of Adrenaline

Adrenaline prepares the body for immediate action by triggering several physiological changes, including:

Increased heart rate: to pump blood faster around the body, delivering oxygen and glucose to muscles and the brain for quick response.

Increased breathing rate: to increase oxygen intake, supporting the muscles and brain during heightened activity.

Dilated pupils: to improve vision and increase awareness of the surrounding environment.

Reduced digestion: blood flow is redirected away from the digestive system towards the muscles, as digestion is not a priority during a threat.

Increased blood glucose levels: to provide more energy, as adrenaline prompts the liver to release stored glucose.

These changes help to maximise an individual’s physical capabilities, increasing their chances of survival.

Return to Homeostasis

Once the threat has passed, the parasympathetic nervous system takes over to return the body to a state of calm, known as homeostasis.

Heart rate and breathing slow down, digestion resumes, and energy levels are restored to a baseline state.

The Role of Adrenaline in the Fight or Flight Response

Adrenaline is essential for initiating and sustaining the fight or flight response. As a hormone and neurotransmitter, it enables the body to react efficiently in high-stress situations by focusing resources on immediate physical needs.

Survival Adaptation: By increasing alertness, energy, and physical ability, adrenaline equips individuals to react swiftly and appropriately to danger.

Speed of Response: Adrenaline is rapidly released and acts almost instantly, illustrating the body’s priority in responding to threats.

Impact on Mood and Alertness: Elevated adrenaline levels can enhance focus, making the individual more attentive to potential dangers in their environment.

Evaluation of the Fight or Flight Response

Strengths:

• The fight or flight response is highly adaptive for dealing with acute stressors in the environment, enhancing chances of survival by preparing the body for action.
• Understanding this response has implications for understanding anxiety and stress-related disorders, as well as for developing treatments that address abnormal responses to stress.

Limitations:

• The fight or flight response is designed for short-term threats; in modern society, many stressors are chronic (e.g., work stress, social pressures), which can lead to prolonged activation of the fight or flight response.
• Extended or repeated activation of this response can contribute to health problems, such as hypertension, heart disease, and immune system suppression.

Alternative Responses:

Recent research suggests that in addition to the fight or flight response, humans (particularly women) may have a "tend-and-befriend" response to stress, which involves seeking social support rather than engaging in a fight or flight reaction.

Key Terms to Remember

Amygdala: A brain structure involved in emotional processing, responsible for detecting threats and initiating the stress response.

Hypothalamus: The brain's regulatory centre for the autonomic nervous system, signalling the adrenal glands to release adrenaline.

Sympathetic Nervous System: Part of the autonomic nervous system that activates the body’s fight or flight response.

Parasympathetic Nervous System: The part of the autonomic nervous system responsible for returning the body to a state of calm after the threat has passed.

Adrenaline (Epinephrine): A hormone released by the adrenal medulla during stress, causing physical changes that prepare the body to respond to danger.

These notes cover the key aspects of the fight or flight response, with a focus on the role of adrenaline in enabling rapid, adaptive reactions to threats. This understanding is foundational for appreciating how stress affects human behaviour and health.