Fight-or-Flight Response

The fight-or-flight response is an evolutionary survival mechanism that enables humans and animals to react swiftly to life-threatening situations. This response triggers specific bodily reactions when we encounter threatening or stressful situations.

Example: When faced with a threat, muscles tense, heart rate increases, and breathing becomes more rapid.

While this response evolved for survival, it can unfortunately be activated in non-life-threatening situations where fighting or fleeing isn't helpful.

The amygdala plays a crucial role in this response by associating sensory signals with emotions related to fight-or-flight. When activated, it sends a distress signal to the hypothalamus, which then communicates with the rest of the body through the sympathetic nervous system.

Vocabulary: The sympathetic nervous system (SNS) is part of the autonomic nervous system that prepares the body for intense physical activity.

The body responds to two types of stressors:

1. Acute (sudden) stressors, such as a personal attack
2. Chronic (ongoing) stressors, like a stressful job

When the SNS is triggered, it initiates the process of preparing the body for action. It sends a signal to the adrenal medulla, which releases adrenaline into the bloodstream. Adrenaline causes several physiological changes:

• Increased heart rate and blood pressure
• Rapid breathing
• Release of blood sugar and fats for energy

Highlight: The parasympathetic nervous system helps return the body to its normal state after the threat has passed by slowing heart rate, reducing blood pressure, and restarting digestion.

For chronic stressors, a second system called the HPA axis is activated. This system involves the hypothalamus, pituitary, and adrenal glands, and relies on a series of hormonal signals to keep the SNS working.

Definition: The HPA axis $Hypothalamic-Pituitary-Adrenal axis$ is a complex set of interactions between the hypothalamus, pituitary gland, and adrenal glands that regulates many bodily processes, including stress response.

The process involves:

1. The hypothalamus releases corticotrophin-releasing hormone (CRH)
2. CRH causes the pituitary gland to produce and release adrenocorticotrophic hormone (ACTH)
3. ACTH stimulates the adrenal cortex to release stress-related hormones, including cortisol

Vocabulary: Cortisol is a hormone that plays a vital role in the body's stress response.

The system efficiently regulates itself through feedback mechanisms, with both the hypothalamus and pituitary gland having special receptors that monitor circulating cortisol levels.

Highlight: Understanding the fight or flight response is crucial for A Level Psychology students, particularly in the context of biopsychology and stress response topics.