physiology of motivated behaviors unit 8 study guides

Key Concepts and Definitions

• Stress involves a perceived threat to homeostasis or well-being that elicits physiological and behavioral responses
• Stressors encompass external or internal stimuli that trigger the stress response (physical, psychological, or social factors)
• Allostasis represents the process of maintaining stability through physiological or behavioral change in response to stressors
  • Allostatic load refers to the cumulative wear and tear on the body resulting from chronic stress and inefficient allostasis
• Eustress denotes positive stress that enhances motivation, performance, and well-being (completing a challenging project)
• Distress signifies negative stress that overwhelms coping abilities and impairs functioning (job loss or relationship difficulties)
• Acute stress involves a brief, intense stressor that rapidly activates the stress response and resolves quickly
• Chronic stress entails persistent or recurring stressors that maintain a prolonged activation of the stress response

Physiological Basis of Stress

• The hypothalamic-pituitary-adrenal (HPA) axis plays a central role in the stress response by regulating the release of glucocorticoids (cortisol)
  • Corticotropin-releasing hormone (CRH) from the hypothalamus stimulates the pituitary gland to secrete adrenocorticotropic hormone (ACTH)
  • ACTH triggers the adrenal cortex to release cortisol, which mobilizes energy resources and modulates immune function
• The sympathetic nervous system (SNS) activates the "fight-or-flight" response during stress
  • Releases catecholamines (epinephrine and norepinephrine) from the adrenal medulla to increase heart rate, blood pressure, and glucose levels
• The parasympathetic nervous system (PNS) promotes "rest-and-digest" functions and helps restore homeostasis after stress
• Neurotransmitters such as serotonin, dopamine, and GABA modulate stress reactivity and emotional regulation
• The amygdala processes emotional aspects of stress and triggers the HPA axis and SNS activation
• The prefrontal cortex regulates the stress response by exerting top-down control over the amygdala and other subcortical regions

Stress Response Systems

• The sympathetic-adrenal-medullary (SAM) axis initiates the rapid "fight-or-flight" response to acute stressors
  • Sympathetic activation leads to the release of epinephrine and norepinephrine from the adrenal medulla
  • Effects include increased heart rate, blood pressure, respiration, and glucose mobilization to prepare for action
• The hypothalamic-pituitary-adrenal (HPA) axis mediates the slower, sustained response to prolonged stressors
  • CRH from the hypothalamus stimulates ACTH release from the pituitary, which triggers cortisol secretion from the adrenal cortex
  • Cortisol enhances glucose availability, suppresses immune function, and modulates brain function and behavior
• Negative feedback loops regulate the stress response to prevent overactivation and restore homeostasis
  • Cortisol inhibits further CRH and ACTH release, while the hippocampus and prefrontal cortex exert inhibitory control over the HPA axis
• Chronic stress can lead to dysregulation of the SAM and HPA axes, resulting in allostatic load and adverse health outcomes

Types of Stressors

• Physical stressors involve direct challenges to physiological homeostasis (injury, infection, extreme temperatures)
• Psychological stressors encompass perceived threats to well-being or self-esteem (work deadlines, public speaking, relationship conflicts)
  • Anticipatory stressors involve the expectation of future challenges or demands (upcoming exams or job interviews)
• Social stressors arise from interpersonal interactions or societal pressures (discrimination, social isolation, financial hardship)
• Developmental stressors occur during critical periods of growth and development (puberty, pregnancy, aging)
• Traumatic stressors entail severe, life-threatening events that overwhelm coping abilities (natural disasters, violence, abuse)
• Daily hassles represent minor, recurring stressors that can accumulate over time (traffic congestion, household chores)
• Major life events involve significant changes or transitions that require adaptation (marriage, divorce, job loss, bereavement)

Arousal and Its Relationship to Stress

• Arousal refers to the state of physiological and psychological activation or alertness
• The Yerkes-Dodson law describes the inverted-U relationship between arousal and performance
  • Moderate levels of arousal enhance cognitive performance and task engagement (flow state)
  • Excessive arousal leads to anxiety, impaired concentration, and decreased performance
• Eustress represents optimal arousal that facilitates growth, creativity, and peak performance
• Distress occurs when arousal exceeds an individual's coping capacity, leading to strain and impairment
• Stress appraisal involves the cognitive evaluation of a stressor as a challenge (eustress) or threat (distress)
  • Challenge appraisals perceive the stressor as an opportunity for growth and mobilize coping resources
  • Threat appraisals view the stressor as overwhelming or uncontrollable, leading to feelings of helplessness or despair
• Individual differences in stress reactivity and arousal regulation influence the impact of stressors on well-being and performance

Coping Mechanisms and Strategies

• Problem-focused coping involves active efforts to modify or eliminate the source of stress (problem-solving, time management, assertiveness)
• Emotion-focused coping aims to regulate the emotional response to stress (relaxation techniques, social support, cognitive reappraisal)
  • Adaptive emotion-focused coping strategies promote resilience and well-being (mindfulness, positive self-talk)
  • Maladaptive emotion-focused coping strategies provide temporary relief but may exacerbate stress in the long run (substance abuse, avoidance, rumination)
• Social support buffers the impact of stress by providing emotional comfort, practical assistance, and a sense of belonging
• Cognitive-behavioral interventions target stress-related thoughts and behaviors to enhance coping skills (stress inoculation training, cognitive restructuring)
• Lifestyle factors such as regular exercise, a balanced diet, and sufficient sleep promote stress resilience and overall well-being
• Mindfulness-based stress reduction (MBSR) cultivates present-moment awareness and acceptance to reduce stress reactivity
• Biofeedback techniques help individuals regulate physiological stress responses by providing real-time feedback on bodily functions (heart rate, muscle tension)

Health Implications of Chronic Stress

• Chronic stress contributes to the development and exacerbation of various physical and mental health conditions
• Cardiovascular disease: Chronic stress increases the risk of hypertension, atherosclerosis, and coronary heart disease
  • Stress-induced inflammation, endothelial dysfunction, and unhealthy behaviors (smoking, overeating) mediate this relationship
• Metabolic disorders: Prolonged stress exposure disrupts glucose metabolism and increases the risk of obesity, insulin resistance, and type 2 diabetes
• Immune dysfunction: Chronic stress suppresses immune function, increasing susceptibility to infections and prolonging wound healing
  • Stress-induced inflammation also contributes to autoimmune disorders and chronic inflammatory conditions
• Mental health disorders: Chronic stress is a risk factor for depression, anxiety disorders, and post-traumatic stress disorder (PTSD)
  • Stress-induced changes in neurotransmitter systems and brain structure (hippocampal atrophy) underlie these associations
• Cognitive impairment: Chronic stress impairs memory, attention, and decision-making abilities, particularly in the prefrontal cortex and hippocampus
• Accelerated aging: Chronic stress contributes to telomere shortening and oxidative stress, which are markers of cellular aging and age-related diseases

Current Research and Future Directions

• Investigating the role of epigenetic mechanisms in stress vulnerability and resilience
  • Stress-induced changes in DNA methylation and histone modifications can alter gene expression and stress reactivity across the lifespan
• Exploring the gut-brain axis in stress regulation and mental health
  • The bidirectional communication between the gut microbiome and the central nervous system modulates stress responses and emotional well-being
• Developing personalized stress management interventions based on individual differences in stress reactivity and coping styles
  • Genetic, epigenetic, and personality factors influence stress susceptibility and treatment response
• Examining the impact of early life stress on brain development and long-term health outcomes
  • Adverse childhood experiences (ACEs) can sensitize stress response systems and increase the risk of chronic diseases in adulthood
• Investigating the effectiveness of technology-based stress management tools (mobile apps, wearable devices, virtual reality)
  • These interventions offer accessible, cost-effective, and scalable solutions for stress reduction and prevention
• Studying the role of social determinants of health in stress-related disparities
  • Socioeconomic status, discrimination, and access to resources shape stress exposure and coping abilities across populations
• Integrating stress management into primary care and public health initiatives to promote population-level well-being and prevent chronic diseases