Chapter 12Chapter 12

The Biology of Emotion and Stress

StressStressStressor - An event that either

strains or overwhelms the ability of an organism to adjust to the environment.

Types of StressorsTypes of StressorsPhysiological stressors include extreme cold or heat, the invasion of dangerous microorganisms, and physical injury.

Psychological stressors include the death of a relative or friend, an upcoming exam, and being fired from a job.

Ben Fogle 2012

StressStressPressure - An expectation to behave

in a specific way within a particular time frame.

Conflict - The inability to satisfy two or more incompatible motives.

Frustration - The obstruction of achieving a goal.

Stress response - The psychological and physiological changes that occur when we encounter a stressor; determines whether we are able to adapt to the stressful experience.

Biological Reactions to Biological Reactions to StressorsStressorsGeneral Adaptation Syndrome

(GAS) - A pattern of physiological responses to a physiological or psychological stressor; all stressors produce this response.

The GAS has three stages:• Alarm stage• Resistance stage• Exhaustion stage

Han Selye

The Alarm StageThe Alarm StageCharacterized by intense sympathetic nervous

system arousal; also called alarm reaction.

Emergency reaction mobilizes our resources and prepares us for “fight or flight,” enabling us to cope behaviorally with stressful experiences.

Alarm reaction lasts for a relatively short time.

When the stressor ends, the parasympathetic nervous system takes over, restoring our physiological reserves to pre-stressor levels.

If the stressor continues, however, we enter the second stage of the GAS.

The Resistance StageThe Resistance StageCharacterized by the mobilization of

physiological resources to cope with a prolonged stressor.

All physiological systems not directly involved in stress resistance are inhibited in this stage.

A prolonged stressor continues the hypothalamic activation causing an increased release of adrenocorticotropic hormone (ACTH) from the anterior pituitary gland.

The Resistance StageThe Resistance StageACTH released into the bloodstream

continues to stimulate the manufacture and release of glucocorticoid hormones (which provides continued energy supply) from the adrenal cortex.

This sequence of structures, the hypothalamus, pituitary gland, and adrenal cortex, is part of the stress axis.

The Exhaustion StageThe Exhaustion Stage

If the stressor continues indefinitely, an animal eventually depletes its physiological resources, resulting in failure of the body’s defense systems and eventually death.

Overtraining syndrome - disorder caused by excessive training by athletes; characterized by decreased performance, chronic fatigue, mood changes, and evidence of a compromised immune system.

The Three The Three Stages of Stages of the the GeneralGeneralAdaptatioAdaptationnSyndromeSyndrome

Diseases of adaptationDiseases of adaptation

An illness caused by the efforts of the body to cope with stressors.

Essential hypertension Gastric or peptic ulcers Colitis

Stress reactions can both cause these illnesses and intensify their severity.

Stress and NeuroplasticityStress and Neuroplasticity• Chronic stress suppresses cellular

proliferation and leads to a shortening and loss of dendrites in the hippocampus.

• By preventing the cellular changes that accompany learning and memory, stressors can have a profound effect on the ability to learn and remember.

• Not all stress has negative consequences:

Acute stress enhances both the immune system and the memory of potentially threatening events.

Coping With StressorsCoping With Stressors

Distress - Negative stress

Eustress - Positive stress with beneficial effects

Different people respond differently to the same stressor. Some people have an intense alarm reaction to a stressor that causes only a low or moderate reaction in other people.

These responsivity differences influence disease development

Coping Behaviors: Type A, Coping Behaviors: Type A, Type BType BType A - A set of behaviors that includes an

excessive competitive drive, an intense sense of time urgency, and high aggressiveness.

Type B - A set of behaviors that are relatively relaxed, patient, and easy-going.

Type A’s are twice as likely to have a heart attack as type Bs

Type A is an independent risk factor for developing coronary heart

disease.

Why Are Type A’s More at Why Are Type A’s More at Risk for Coronary Disease?Risk for Coronary Disease?Significantly more reactive to stressors.Have greater norepinephrine release which

can accelerate arterial damage, enhance blood clot formation, and produce cardiac arrhythmias.

Smoke more, sleep less, drink more caffeine

Show more hostility and are quick-tempered anger, which appear to be independent risk factors for coronary heart disease.

HardinessHardinessIs the ability to cope effectively with stressors because of -a high level of commitmenta perception that change is a challenge rather than a threata sense of control over events.

May explain why some individuals thrive despite being raised in extremely dysfunctional circumstances, while others fail in the most advantageous environments.

HardinessHardinessHardy people are less biologically

responsive to stressors; cope better under stress

Hardy people have a greater sense of purpose, a stronger commitment to self, an internal locus of control, and experience less emotional stress.

Hardiness has been shown to be inversely related to depression and fatigue.