© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Chapter 5 The Physical Basis of Stress

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Overview nThis chapter uProvides an overview of the physical basis of stress through an in-depth analysis of Selye’s general adaptation syndrome (GAS) uDescribes how the GAS responds to immediate and longer-term threats uEnds with a critical analysis of Selye’s work based on recent studies

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Outline uOverview of the major body systems involved in the stress response uFight-or-flight: An alarm reaction uResistance: A chronic, long-term stress response uThe physiology of exhaustion uA critical look at general adaptation syndrome (GAS)

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Major Body Systems Involved in the Stress Response nCommunication, control, and integration uThe endocrine system uThe nervous system

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Other Major Body Systems Involved in the Stress Response nTransportation and defense uCardiovascular (circulatory) system uImmune system

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Other Major Body Systems Involved in the Stress Response nSupport and Movement uMuscular system nRespiration, Nutrition, and Excretion uGas exchange: The respiratory system uNutrition and excretion: The digestive system

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images The Nervous System and Fight-or- Flight (An Alarm Reation) nFight-or-flight stress response helps us get out of harm’s way nSelye’s General Adaptation Syndrome (GAS) alarm phase nStress response: a series of phases that continue to exact a toll on our bodies until we remove or cope with the stressor that initiates is

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Axes and Pathways nEverly and Lating use these terms to describe the routes traveled through the body after a potential stressor is appraised as threatening nThree different pathways uThe neural axis uThe neuroendocrine axis (a.k.a. the sympathoadrenomedullary system, or SAM) uThe endocrine axis (contains the hypothalamic- pituitary-adrenal-cortical system, or HPAC) nThe axes expand on Selye’s work

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images The Neural Axis nThe central nervous system: brain and spinal column nThe peripheral nervous system: all the other nerve pathways

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Fight-or-Flight: The Brain nThe fight-or-flight response uOriginates with the brain’s perception of threat nDifferent parts of the brain are involved in the stress response uThe cerebral cortex—covers the cerebrum and controls higher thought processes uThe diencephalon—forms the central brain core and receives and routes messages

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Fight-or-Flight: The Brain (continued) nThe limbic system uLinks the emotional brain with the thinking, rational brain nThe brain stem uProduces autonomic functions (necessary for survival) uIs pathway for both general and specific cortical arousal through the reticular activating system (RAS)

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Fight-or-Flight: The Spinal Cord nThe lifeline between the brain and the rest of the body

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Fight-or-Flight: The Peripheral Nervous System nThe somatic nervous system uTransmits messages under our conscious control nThe autonomic nervous system uControls functions that are unconscious uSympathetic branch: activates stress responses uParasympathetic branch: deactivates stress responses (activates relaxation responses)

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Fight-or-Flight: The Endocrine System of the Neuroendocrine Axis nProduces hormones associated with alarm nAdrenal glands play the most significant role in the stress response uEpinephrine (adrenaline) uNorepinephrine (noradrenaline)

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Resistance: A Continuous, Long- Term Stress Response nThe physiology of resistance: The body not at rest but also not in the throes of alarm nRoles played by uThe brain: the cerebral cortex, diencephalon, limbic system, and brain stem uThe endocrine axes: adrenocortical, somatotropic, thyroid, and pituitary systems

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Resistance—The Cerebral Cortex uThe cerebral cortex—the key part of the brain involved in resistance FOur thoughts about stressors, especially illogical thoughts, keep them alive or allow them to dissipate

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Resistance—The Limbic System nInteracts with the cortex as our emotions interact with our thoughts nProlongs or reduces the stress response

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Resistance—The Endocrine System nThe pituitary is known as the master gland nAll activities are orchestrated by the pituitary gland through the hypothalamus

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Resistance—The Adrenal Function nThe medulla secretes two key groups of hormones uGluccocorticoids (sugars) FCortisol provides energy, reduces inflammation, prolongs stress response uMineralocorticoids (salts) FAldosterone keeps blood pressure elevated

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images The Physiology of Exhaustion nSelye believed all living things have a finite amount of energy to adapt to stress uWhen that is used up, one suffers exhaustion uOrganisms vary in how they become exhausted

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Exhaustion—The Weak Link nSelye asserted all living things have a “weak link,” the first part to fail nChronic stress puts a heavy demand on strategic body parts FHeart, blood vessels, and adrenal and thyroid glands are most susceptible

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images General Adaptation Syndrome (GAS) (A Review) nDeveloped by Selye, GAS has three distinguishable phases uAlarm uResistance uExhaustion

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images A Critical Look at GAS nTwo major challenges in recent years uNonspecificity—Goldstein FIdentified different responses to seven specific stressors: water deprivation, salt deprivation, posture changes, eating a large meal, exercise, hemorrhage, and temperature alteration uEustress—Mason and Frankenhauser FFound body response to threat different from body response to challenge

© 2007 McGraw-Hill Higher Education. All rights reserved. Akira Kaede/Getty Images Chapter 5: The Physical Basis of Stress nSummary