Topic 2: Physiological Changes During Stress: Impacts on Body and Brain


Stress, while often considered an abstract psychological concept, induces palpable physiological changes in our body and brain. These changes, which evolved as adaptive survival mechanisms, can have significant impacts on our well-being, especially when stress becomes chronic. Understanding these alterations provides insight into the comprehensive nature of stress and its broader implications on health.

Hormonal Release

  1. Adrenaline: Produced by the adrenal glands, adrenaline prepares the body for the fight-or-flight response. It increases heart rate, elevates blood pressure, and boosts energy supplies.

    Example: The palpable heart-pounding before a public speech is largely due to a surge in adrenaline.

  2. Cortisol: Termed the “stress hormone,” cortisol releases sugars into the bloodstream, enhances the brain’s use of glucose, and curtails nonessential functions like digestion.

    Example: Ever noticed an upset stomach during stressful times? Elevated cortisol can divert resources away from digestion.

Effects on the Cardiovascular System

  • Increased Heart Rate and Blood Pressure: This ensures that muscles get the oxygen and nutrients needed to either fight or flee.

    Example: Feeling one’s pulse racing during an intense confrontation.

  • Vasoconstriction: Blood vessels constrict, which also elevates blood pressure.

    Example: Chronic stress can contribute to long-term conditions like hypertension.

Brain and Nervous System

  1. Amygdala Activation: The brain’s “alarm system,” the amygdala, becomes more active, identifying potential threats and invoking immediate reactions.

  2. Prefrontal Cortex Suppression: This brain region, responsible for logical thinking and decision-making, becomes less active, allowing more instinctual parts of the brain to take charge during immediate threats.

    Example: Ever regretted a hasty decision made in the heat of the moment? This is the prefrontal cortex being overruled by more reactive brain areas.

  3. Neural Plasticity: Chronic stress can alter neural connections and even lead to a reduction in size of the prefrontal cortex.

  4. Heightened Alertness: Activation of the sympathetic nervous system enhances sensory perceptions, making one more alert.

Metabolic and Digestive Changes

  1. Metabolism Boost: The body releases sugar and fat to produce energy.

  2. Digestion Suppression: As the body prioritizes immediate survival, systems like digestion are deemed non-essential and thus slowed.

    Example: The “butterflies” in the stomach or even nausea during stress.

Musculoskeletal System

  • Muscle Tension: Muscles tighten up, ready to spring into action. This can lead to stress-related disorders like tension-type headaches or migraines.

    Example: The feeling of stiff shoulders or a tight neck after a stressful day.

Respiratory Changes

  • Rapid Breathing: The lungs take in more oxygen to distribute to vital organs. This can exacerbate conditions like asthma or lead to feelings of breathlessness.

Reproductive and Immune Systems

  1. Reproductive Issues: Chronic stress can affect libido, menstrual cycles, and even sperm production.

  2. Immune Response: Short bursts of stress can boost the immune system, but chronic stress suppresses it, increasing susceptibility to illnesses.

    Example: Falling ill after prolonged periods of work without breaks or relaxation.


The physiological changes during stress highlight the body’s remarkable ability to adapt and respond to threats. However, in a world where stressors can be chronic and relentless, these changes can become maladaptive, leading to health issues. Recognizing and understanding these alterations is the first step towards effective stress management, ensuring that our bodies and minds remain in harmony.