Physiological Responses to Stress

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Physiological Responses to Stress : 

Physiological Responses to Stress Pupils dilate to admit more light for more sensitive vision Mucous membranes of nose & throat shrink while muscles force wider opening of passages to permit easier air flow Secretion of saliva decreases Bronchi dilate Perspiration increases –evaporation cools body Liver releases sugar into blood stream – energy for muscles and brain Bone marrow throughout body produces more while blood cells Endorphins are released Hearing becomes more acute Heart rate increases Spleen releases more red blood cells Adrenal glands release adrenalin and noradrenalin resulting in increased blood pressure, increased heart rate, increased fatty acids in blood stream and increased blood sugar Voluntary skeletal muscles contract throughout the body Pancreas decreases secretion

Physiological Health Consequences of Stress : 

Physiological Health Consequences of Stress Increased Risk of Myocardial Infarction Increased Risk of Impaired Immune System Functioning

The Research : 

The Research Early research (1932) was done by Walter Cannon who described the Fight-or-Flight Response. Stress chemicals called catecholamines are at the center of this response. This is the short-term stress or acute stress response. Later Research (1956, 1976) was done by Hans Selye who described the General Adaptation Syndrome. Stress chemicals called glucocorticoids are involved in this response. This is the long-term stress or the vigilant response to stress.

The Early Research: Fight-or-Flight : 

The Early Research: Fight-or-Flight Cannon described a series of physiological responses of the organism when faced with a threat. These automatic responses prepared the body to either fight or flee the threat. (Saber Tooth Tiger and the Caveman).

Physiological Responses to Stress : 

Physiological Responses to Stress Pupils dilate to admit more light for more sensitive vision Mucous membranes of nose & throat shrink while muscles force wider opening of passages to permit easier air flow Secretion of saliva decreases Bronchi dilate Perspiration increases –evaporation cools body Liver releases sugar into blood stream – energy for muscles and brain Bone marrow throughout body produces more while blood cells Endorphins are released Hearing becomes more acute Heart rate increases Spleen releases more red blood cells Adrenal glands release adrenalin and noradrenalin resulting in increased blood pressure, increased heart rate, increased fatty acids in blood stream and increased blood sugar Voluntary skeletal muscles contract throughout the body Pancreas decreases secretion

Good or Bad? : 

Good or Bad? These acute response are “good” for survival… But in our world today, we don’t have Saber Tooth Tigers…or, do we? Who (what) are the modern-day equivalents of the Saber Tooth Tigers?

The Adrenal Glands : 

The Adrenal Glands

The Two Pathways : 

The Two Pathways

The N.S. Response to Stress : 

The N.S. Response to Stress Perceived Threat Sympathetic branch of Autonomic Nervous System is activated. Parasympathetic branch is shut down Medulla of the Adrenal Glands is stimulated causing it to release adrenalin (catecholamines). Adrenalin cause increased heart rate, increased blood pressure, deeper faster breathing, increased perspiration, increased muscle tension, increased oxygen consumption,, increased platelet activity.

The Endocrine Response to Stress : 

The Endocrine Response to Stress Perceived Threat Cortex of Adrenal Glands is stimulated resulting in the release of Cortisol (glucocorticoids) Cortisol causes increased heart rate, increased blood pressure, deeper faster breathing, increased perspiration, increased muscle tension, increased oxygen consumption,, increased platelet activity. Pituitary gland is stimulated releasing ACTH

Stress and Heart Disease : 

Stress and Heart Disease Adrenal CORTEX Cortisol (associated with long-term effect of stress) – loss of control Adrenal MEDULLA Adrenalin (associated with acute or short term response to stress. Increased FFA, increased Platelet numbers, increased Serum Cholesterol, decreased Potassium, direct injury producing effect of coronary artery walls. Increased Platelet stickiness, direct injury producing effect on coronary artery walls, over contractibility of myocardium, increased FFA, shearing effect on plaques resulting in clotting system.

Summary of how Stress Increases the Risk of a Heart Attack : 

Summary of how Stress Increases the Risk of a Heart Attack Stress Hormones (Cortisol & Adrenaline) elevate Blood Pressure. Adrenalin increases blood platelet stickiness. Cortisol increases blood platelet numbers. Adrenalin & Cortisol have a direct injury-producing effect on artery walls (contributes to atherosclerosis). Adrenaline causes over-contractibility of heart muscle (rupture fibers?). Cortisol increases cholesterol levels and lowers potassium levels.