Stress: Internal and External Stressors

1. Defining Stress

• Stress: A state of physiological and psychological arousal produced by internal or external stressors that are perceived by the individual as challenging or exceeding their ability or resources to cope.
• Stressor: Any event, situation, object, person, or other condition that causes stress.
• Stress Response: The physiological and psychological reactions experienced when confronted by a stressor.

KEY TAKEAWAY: Stress is subjective. What one person finds stressful, another may not.

2. Types of Stressors

2.1 Internal Stressors

• Originate within the individual.
• Examples:
  • Personal beliefs
  • Thoughts
  • Feelings
  • Physical illness
  • Lack of sleep
  • Worrying about academic performance

2.2 External Stressors

• Originate outside the individual, from situations and events in the environment.
• Examples:
  • School demands (exams, assignments)
  • Work pressures
  • Social interactions
  • Relationships
  • Environmental factors (noise, crowding)
  • Major life events (e.g., death of a loved one, moving house)
  • Sociocultural factors (discrimination, poverty)

EXAM TIP: Be prepared to provide specific examples of internal and external stressors in exam questions.

3. Stress Responses

3.1 Psychological Stress Responses

• Emotional: Feelings of anxiety, tension, irritability, sadness, anger, helplessness, hopelessness.
• Cognitive: Difficulties concentrating, memory problems, negative thoughts, catastrophic thinking.
• Behavioral: Changes in eating habits, sleep disturbances, social withdrawal, increased substance use.

3.2 Physiological Stress Responses

• Involve bodily changes, largely due to the activation of the autonomic nervous system (ANS).
• Examples:
  • Increased heart rate
  • Increased blood pressure
  • Sweating
  • Muscle tension
  • Dilated pupils
  • Suppressed immune system

COMMON MISTAKE: Confusing stress (the state) with stressors (the causes of stress).

4. Acute vs. Chronic Stress

STUDY HINT: Create a table like the one above to compare different concepts related to stress.

5. The Fight-Flight-Freeze Response (Acute Stress)

• An involuntary, immediate reaction to a perceived threat or stressor.
• Prepares the body for:
  • Fight: Confronting and fighting off the threat.
  • Flight: Escaping from the threat.
  • Freeze: Becoming immobile and silent, avoiding detection.
• Physiological Process:
  1. Threat perceived: Sensory information is sent to the amygdala (processes emotions, especially fear).
  2. Hypothalamus activated: The hypothalamus activates the sympathetic nervous system (SNS).
  3. SNS activation: The SNS stimulates the adrenal medulla (inner part of the adrenal gland).
  4. Adrenal medulla releases hormones: Adrenaline (epinephrine) and noradrenaline (norepinephrine) are released into the bloodstream.
  5. Physiological changes:
     • Increased heart rate and blood pressure
     • Increased respiration rate
     • Dilated pupils
     • Increased blood flow to muscles
     • Release of glucose from the liver for energy
     • Suppression of non-essential functions (e.g., digestion)
• Freeze Response:
  • Characterized by immobility, slowed heart rate, and tense muscles.
  • May occur when fight or flight is not possible or appropriate.
  • Involves both the sympathetic and parasympathetic nervous systems. Initial sympathetic activation is followed by parasympathetic activation, leading to a conservation of energy.

REMEMBER: The fight-flight-freeze response is an adaptive mechanism that helps us survive in threatening situations.

6. Cortisol and Chronic Stress

• Cortisol: A stress hormone released by the adrenal cortex (outer part of the adrenal gland) in response to a stressor.
• HPA Axis: The hypothalamic-pituitary-adrenal (HPA) axis is activated in chronic stress.
  1. Hypothalamus releases CRH: The hypothalamus releases corticotropin-releasing hormone (CRH).
  2. Pituitary gland releases ACTH: CRH stimulates the pituitary gland to release adrenocorticotropic hormone (ACTH).
  3. Adrenal cortex releases cortisol: ACTH stimulates the adrenal cortex to release cortisol.
• Role of Cortisol:
  • Energizes the body by increasing blood sugar levels.
  • Suppresses the immune system.
  • Has anti-inflammatory effects.
• Effects of Prolonged Cortisol Release (Chronic Stress):
  • Impaired immune system functioning
  • Increased risk of illness
  • High blood pressure
  • Cardiovascular disease
  • Diabetes
  • Mental health problems (e.g., anxiety, depression)
  • Memory and learning problems
  • Weight gain
  • Sleep disturbances

APPLICATION: Healthcare workers during the COVID-19 pandemic experienced high levels of chronic stress, evidenced by elevated cortisol levels, leading to potential long-term health consequences.

7. Comparing Acute and Chronic Stress Responses

VCAA FOCUS: VCAA exam questions often ask about the differences between acute and chronic stress responses, and the role of specific hormones in each.