Stress and Physiological Response

Stress Definition and History

• Stress is a circumstance that disturbs the normal physiological or psychological functioning of a person.
• Walter Cannon (1875-1945) conducted the first systematic study of the relation of stress to disease in the 1920s.
• Cannon demonstrated that stimulation of the autonomic nervous system, particularly the sympathetic system, readies the organism for the "fight or flight" response.

The "Fight or Flight" Response

• The "fight or flight" response is characterized by hypertension, tachycardia, and increased cardiac output.
• This response is useful in animals who can fight or flee, but in humans who cannot, it results in disease (e.g., cardiovascular disorders).

Hans Selye's Contributions

• Hans Selye (1907-1982) observed that many highly diverse ways of perturbing the organism resulted in common physiological responses.
• Selye developed a model of stress called the "general adaptation syndrome", which consists of three phases: the alarm reaction, the stage of resistance, and the stage of exhaustion.
• Selye believed that stress, by definition, need not always be unpleasant, and called unpleasant stress "distress".

The General Adaptation Syndrome

• The general adaptation syndrome is a nonspecific bodily response to any demand caused by either pleasant or unpleasant conditions.
• The body reacts to stress by putting into motion a set of responses to diminish the impact of the stressor and restore homeostasis.
• Stressors can be either pleasant or unpleasant (real, symbolic, or imagined) conditions that threaten an individual and cause stress responses.

Types of Stressors

• Physical stressors: environmental pollution, sudden and extreme temperature changes, exposure to diseases, excessive exercise, electrical shock, injury, etc.
• Psychological stressors: any feeling or thought that creates emotional and apprehensive threat perception by individuals.
• Psycho-social stressors: conflicts related to social and interpersonal relationships, extreme domestic discipline or social coercion, social exclusion, sequestration, etc.

Physiological Responses to Stress

• Autonomic activation symptoms: tachycardia, sweating, hypertension, hyperglycemia, muscle strain, etc.
• Neuroendocrine and immune responses to stress: activation of noradrenergic, serotonergic, and dopaminergic systems in the brain, and release of catecholamines from the autonomic nervous system.

Immune Responses to Stress

• Life stresses have been shown to have a deleterious effect on antiviral immunity in humans.
• In response to stress, Corticothropine Releasing Factor (CRF) is secreted from the hypothalamus into the hypophysial-pituitary-portal system.

Consequences of Stress

• Stress can have deleterious effects on physical health, leading to conditions such as obesity, headache, acne, asthma, and many types of cancer.
• Stress can also lead to psychiatric conditions such as anxiety disorders, depression, and substance abuse.
• Inadequate coping mechanisms to stress can cause serious behavioral and psychiatric conditions.

Stress Definition and History

• Stress is a circumstance that disturbs the normal physiological or psychological functioning of a person.
• Walter Cannon (1875-1945) conducted the first systematic study of the relation of stress to disease in the 1920s.
• Cannon demonstrated that stimulation of the autonomic nervous system, particularly the sympathetic system, readies the organism for the "fight or flight" response.

The "Fight or Flight" Response

• The "fight or flight" response is characterized by hypertension, tachycardia, and increased cardiac output.
• This response is useful in animals who can fight or flee, but in humans who cannot, it results in disease (e.g., cardiovascular disorders).

Hans Selye's Contributions

• Hans Selye (1907-1982) observed that many highly diverse ways of perturbing the organism resulted in common physiological responses.
• Selye developed a model of stress called the "general adaptation syndrome", which consists of three phases: the alarm reaction, the stage of resistance, and the stage of exhaustion.
• Selye believed that stress, by definition, need not always be unpleasant, and called unpleasant stress "distress".

The General Adaptation Syndrome

• The general adaptation syndrome is a nonspecific bodily response to any demand caused by either pleasant or unpleasant conditions.
• The body reacts to stress by putting into motion a set of responses to diminish the impact of the stressor and restore homeostasis.
• Stressors can be either pleasant or unpleasant (real, symbolic, or imagined) conditions that threaten an individual and cause stress responses.

Types of Stressors

• Physical stressors: environmental pollution, sudden and extreme temperature changes, exposure to diseases, excessive exercise, electrical shock, injury, etc.
• Psychological stressors: any feeling or thought that creates emotional and apprehensive threat perception by individuals.
• Psycho-social stressors: conflicts related to social and interpersonal relationships, extreme domestic discipline or social coercion, social exclusion, sequestration, etc.

Physiological Responses to Stress

• Autonomic activation symptoms: tachycardia, sweating, hypertension, hyperglycemia, muscle strain, etc.
• Neuroendocrine and immune responses to stress: activation of noradrenergic, serotonergic, and dopaminergic systems in the brain, and release of catecholamines from the autonomic nervous system.

Immune Responses to Stress

• Life stresses have been shown to have a deleterious effect on antiviral immunity in humans.
• In response to stress, Corticothropine Releasing Factor (CRF) is secreted from the hypothalamus into the hypophysial-pituitary-portal system.

Consequences of Stress

• Stress can have deleterious effects on physical health, leading to conditions such as obesity, headache, acne, asthma, and many types of cancer.
• Stress can also lead to psychiatric conditions such as anxiety disorders, depression, and substance abuse.
• Inadequate coping mechanisms to stress can cause serious behavioral and psychiatric conditions.