Coordinating Systems in Action - Stress and Biological Rhythms
Page 2: Lecture Outline
Major Topics
Neurobiology of Stress
Functions of stress
Hypothalamic-Pituitary axes and chronic stress responses
Biological Rhythms
Coordination of systems
Feedback loops in transcription-translation
Circadian regulation by circuits, physiology, and behavior
Page 3: Lecture Structure
Key Concepts
Definition of Stress
Hypothalamic-Pituitary Axis
Acute and Chronic Stress Response
Biological Rhythms
Circadian Regulation
Page 4: Defining Stress
Concept of Stress
Definition: Stress is anything that disrupts homeostasis; includes injury, illness, and extreme temperature.
Allostasis: The process of achieving stability through physiological/behavioral changes; crucial for adapting to stimuli (e.g., seasonal exams).
Page 6: Stressors
Types of Stressors
Major Life Stressors - extreme weather
Daily Hassles - traffic
Page 7: Stress Response Components
Key Components of the Stress Response
Hypothalamus
Releases Corticotropin-Releasing Hormone
Pituitary Gland
Releases Adrenocorticotropic Hormone (ACTH)
Adrenal Gland
Cortex - Produces Glucocorticoids (e.g., cortisol)
Medulla - Produces catecholamines (Epinephrine and Norepinephrine)
Page 8: Physiological Mechanism of Stress
Peripheral Nervous System Activity
Effect on epinephrine and norepinephrine concentrations around PhD exam periods indicating stress responses over days before and after the exam.
Page 9: Long-Term Impact of Stress
Health Consequences
Long-term stress leads to negative health outcomes such as inhibited wound healing in caregivers over time
Page 10: Circadian Rhythms
Biological Cycles
Definition: Daily biological cycles ('circa' = 'around', 'diēs' = 'day').
Characteristics: Roughly 24-hour cycles in various bodily functions like alertness, temperature, and hormone levels; regulated by environmental cues (zeitgebers).
Page 11: Daily Hormonal Rhythms
Stress Hormones and Time
Daily cortisol fluctuations involved in arousal across different times (9 AM to 9 AM).
highest in the morning, lowest at night
Page 12: Suprachiasmatic Nucleus (SCN)
Function of SCN
Specialised hypothalamic cells acting as the brain's master circadian pacemaker.
Informs the pineal gland to secrete melatonin based on light exposure from ganglion cells in retina, controlling sleep-wake cycles.
Page 13: Evidence of SCN Function
Animal Studies
Findings from lesions disrupting users’ circadian rhythms.
Transplanted SCN leading recipient rats to adopt the periodicity of the donor’s SCN.
Page 14: Measuring Melatonin
Melatonin as a Marker
Sleep-promoting hormone, affected by light exposure; measured through saliva or blood to determine circadian phase.
Page 15: Self-Reporting Circadian Rhythms
Outside Laboratory Measures
Utilisation of tools like Munich Chronotype Questionnaire to assess social jet lag and circadian preference misalignment.
Page 16: Early School Start Times
Societal Impact
Analysis of early start times in schools and their effects on sleep duration, contributing to social jet lag and associated issues.
Page 17: Consequences of Sleep Issues
Effects of Insufficient Sleep
Insufficient sleep resulting in various negative impacts on cognition, safety, and mental/physical health.
Page 18: Sleep Restriction Impacts
Study Findings
Research demonstrating cognitive decline associated with restricted school night sleep; insufficient recovery on weekends.
Page 19: Sleep and Emotional Wellbeing
Correlation
Weekday sleep restriction negatively affecting REM, which is crucial for emotion regulation, leading to increased anxiety and negative emotions.
Page 20: Actigraphy Study
Research on Older Adults
Monitoring health outcomes based on sleep patterns observed over 10 years, assessing various health aspects from actiwatch data.
Page 21: Survival Rates from Sleep Data
Impact of Sleep Duration
Analysis of survival rates based on actigraphic sleep duration showing a strong correlation between sleep time and longevity.
Page 22: SCN Transplantation Paradigm
Experimental Evidence
Findings from SCN lesions impacting circadian rhythms and transplantation experiments demonstrating rhythm re-establishment in recipient rats.
Page 23: SCN Characteristics
Biological Clock
Evidence supporting SCN as biological clock regulating circadian rhythms, cellular activity synchronization, and genetic underpinnings in fruitflies.
Page 24: Human SCN Dynamics
Circadian Effects
SCN cells exhibiting individual activity rhythms that synchronize through chemical mechanisms; insights into molecular clock genes.
Page 25: Biello et al. Study (2009)
Age Effects on SCN Activity
Differences in SCN firing patterns among age groups demonstrating no timing discrepancy but changes in amplitude.
Page 26: Age-Related Neurochemicals
Phase Shifting Patterns
Neurochemicals affecting circadian rhythms showing differences in phase shift potential across age demographics.
Page 27: Neurochemical Behavior Patterns
Phase Shift Mechanisms
Behaviors affected by age-related neurochemical changes and their implications on circadian alignment.
Page 28: Study Summary
Circadian Rhythms in Juvenile Sheep
Effects of photoperiod, environment, and weaning on melatonin and behavior in a naturalistic setting.
Page 29: Seasonality of Biological Rhythms
Experimental Findings
Differences observed between long and short photoperiods and their influence on behavioral rhythms.
Page 30: Behavioral Investigations
Barn vs. Pasture Conditions
Exploring behavioral patterns in varied living conditions, with statistical outcomes over differing periods.
Page 31: Seasonal Changes and Sleep Patterns
Day/Time Influences
Seasonal variations causing differences in sleep onset and offset; analysis over time.
Page 32: Night Work and Sleep Disorders
Implications of Work Schedules
Overview of symptoms experienced by night workers, correlation with sleep disorders, and proposed interventions for reducing exposure.