Class 4

Question 1

How Stress Affects Body Systems

Answer 1

Stress impacts various major body systems, contributing to a range of diseases:

• Cardiovascular System: Stress is widely studied in relation to cardiovascular health. Health risk behaviors like smoking can contribute to atherosclerosis (inflammation in arteries), which reduces blood flow and increases blood pressure. Stress is associated with conditions like Coronary Artery Disease, Heart Failure, and Stroke. Research on hypertension focuses on emotions related to struggle and aggression. Factors like conflict, crowding, and chronic exposure to noisy environments can affect blood pressure from an early age.
• Gastrointestinal System: Stress negatively impacts the gut microbiome by promoting harmful bacteria and reducing healthy bacteria, leading to gut inflammation. It can also affect the muscle activity required for digestion. This system is associated with diseases like Crohn’s Disease, Ulcerative Colitis, and Cirrhosis.
• Respiratory System: The “fight-or-flight” response to stress triggers rapid, shallow breathing. The respiratory system is involved in taking in substances and removing waste, and oxygen is needed to utilize nutrients. Stress is linked to conditions such as Asthma and Sleep Apnea.
• Urinary (Renal) System: The kidneys are the main component, filtering blood and playing an important role in blood pressure control. Stress can affect conditions like Chronic Kidney Disease.
• Immune System: This widespread system protects the body from infection using individual cells, primarily white blood cells. The immune system has two main responses: the innate (non-specific) response and the lymphoid (specific, targeted) response involving antibodies. The Central Nervous System (CNS) can both stimulate and dampen immune activity through the Peripheral Nervous System (PNS) and hormones. Sometimes the immune system can overreact to harmless stimuli (allergies) or attack healthy cells (auto-immune disorders).

Question 1

Core Concepts of Psychoneuroimmunology

Answer 1

• Mind-Body Connection: PNI is built on the principle that body systems, which support health and behavior, are influenced by psychosocial factors. Stress, stressors, and our responses to them play a vital role in how our body systems function.
• “Wear and Tear”: The physiological and psychological responses to stress are significant contributors to illness.
• Evolutionary Perspective: Biological structures and emotional responses to stress (like fear and anger) evolved to be adaptive, motivating behaviors such as “fight or flight” to increase survival.
• Modern Maladaptation: While these responses can be adaptive in the short-term (e.g., exam stress motivating studying), they can become maladaptive in the long-term in modern society. Chronic stress can lead to problems like weight gain, loneliness, fatigue, burnout, and illness. It can also contribute to health risk behaviors like smoking and alcohol use.

Question 2

The Physiology of the Stress Response

Answer 2

The body’s response to stress is managed by several interconnected systems:

1. The Nervous System:
   
   • Peripheral Nervous System (PNS): This system includes the Somatic and Autonomic nervous systems.
   • Somatic Nervous System: This is the voluntary system that relays information from the brain to skeletal muscles.
   • Autonomic Nervous System: This involuntary system processes information from the brain and spinal cord to various organ systems. It is divided into two parts:
     
     • Sympathetic Nervous System (SNS): Responsible for the “fight-or-flight” response, preparing the body for a life-threatening situation.
     • Parasympathetic Nervous System: Regulates the body during periods of rest.
2. The Endocrine System: This is a network of glands that produce and release hormones into the bloodstream, controlling various bodily functions for longer periods than the nervous system.

Question 3

Key Research and Findings on Stress

Answer 3

• Early Theories: Physiologist Walter Cannon first theorized the “fight-or-flight” response in the early 1900s, noting the brain responds to physical and psychological challenges. In the 1940s, endocrinologist Hans Selye linked stress to the adrenal hormone cortisol and ulcer formation, arguing that stress is a daily occurrence.
• Psychological Factors and Illness:
  
  • Gastrointestinal Ulcers: The “Executive Monkey” experiment suggested that having control over avoiding a stressor (electric shocks) led to more ulcers, although this study had design flaws like non-random assignment. Follow-up research showed that unpleasant, uncontrollable situations induced ulcers in animals. In humans, the bacterium H. Pylori is a risk factor, but stress can exacerbate it, and ulcers can develop even without the bacteria. Depression and anxiety are also linked to ulcers.
  • Vasovagal Reactions: This is a clear example of stress-related illness where blood flow to the brain decreases, common in people with phobias related to blood, needles, or injury. It is related to the anticipation of harm.
  • The Common Cold: A 2005 study by Cohen showed that participants with greater life stress were more likely to develop cold symptoms after being exposed to a virus, even after controlling for other risk factors like smoking and sleep.

Question 4

The Dual Role of Stress on Immunity

Answer 4

The relationship between stress and the immune system is complex and time-dependent.

• Brief Stressors: Short-term stress is generally adaptive and can increase immune function.
• Long-Term Stressors: Chronic, long-term stress contributes to a reduction in immune activity, largely due to the hormone cortisol. This can exacerbate both physical and psychological health problems and increases the risk of developing autoimmune diseases.

Question 5

Mediating Factors and Future Directions

Answer 5

The impact of stress is not uniform and is influenced by several factors:

• Health Behaviors and Psychosocial Factors: The effects of stress on immunity are mediated by health behaviors (e.g., sleep) and psychosocial factors (e.g., social support, socioeconomic status).
• Early Life Stress (ELS): ELS can have long-term impacts on immune functioning and is linked to adult disease.
• Stress and Aging: Chronic stress can accelerate immunological aging, leading to reduced immune function.
• Future Research: Future studies will likely focus on how specific qualities of a stressor (its type and timing) and individual characteristics make people more or less susceptible to immune dysregulation.