* Log In * Register Now * Help * Home Page * Today's Paper * Video * Most Popular * Times Topics Search All NYTimes.com ____________________ Search New York Times Health Guide * World * U.S. * N.Y. / Region * Business * Technology * Science * Health + Research + Fitness & Nutrition + Money & Policy + Views + Health Guide * Sports * Opinion * Arts * Style * Travel * Jobs * Real Estate * Autos Search Health3,000+ Topics ____________________ Go Send Feedback Health > Times Health Guide > s > Stress and Anxiety > In-Depth Report: The Body's Response Stress and Anxiety * Overview * In-Depth Report + Background + The Body's Response + Possible Complications + Conditions With Similar Symptoms + Treatment + Risk Factors + Lifestyle Changes + Resources + References * News & Features * Reporter's File * Expert Q & A * Questions for Your Doctor * Clinical Trials * 5 Things to Know View & Print In-Depth Report » Multimedia State of the Economy Affects the State of Mind Web Links * National Institute of Mental Health * National Alliance for the Mentally Ill * National Mental Health Association * American Massage Therapy Association * American Institute for Cognitive Therapy * Association for the Advancement of Behavior Therapy * The American Psychiatric Association * The National Association of Social Workers * American Academy of Child and Adolescent Psychiatry * The American Institute of Stress * The Obsessive Compulsive Foundation Related Topics * Grief * Depression * Tremor * Headache * Sweating * Generalized Anxiety Disorder * Phobia - Simple/specific * Obsessive-Compulsive Disorder * Social Phobia Illustrations * Generalized Anxiety Disorder Generalized Anxiety Disorder In-Depth From A.D.A.M. The Body's Response The best way to envision the effect of acute stress is to imagine yourself in a primitive situation, such as being chased by a bear. The Brain's Response to Acute Stress In response to seeing the bear, a part of the brain called the hypothalamic-pituitary-adrenal (HPA) system is activated. Release of Steroid Hormones and the Stress Hormone Cortisol. The HPA systems trigger the production and release of steroid hormones ( glucocorticoids ), including the primary stress hormone cortisol . Cortisol is very important in organizing systems throughout the body (including the heart, lungs, circulation, metabolism, immune systems, and skin) to deal quickly with the bear. Release of Catecholamines. The HPA system also releases certain neurotransmitters (chemical messengers) called catecholamines , particularly those known as dopamine , norepinephrine , and epinephrine (also called adrenaline). Catecholamines activate an area inside the brain called the amygdala , which appears to trigger an emotional response to a stressful event. In the case of the bear, this emotion is most likely fear. Release of Neuropeptide S . The brain releases neuropeptide S, a small protein that modulates stress by decreasing sleep and increasing alertness and a sense of anxiety. This gives the person a sense of urgency to run away from the bear. Effects on Long- and Short-Term Memory. During the stressful event, catecholamines also suppress activity in areas at the front of the brain concerned with short-term memory, concentration, inhibition, and rational thought. This sequence of mental events allows a person to react quickly, either to fight the bear or to flee from it. It also interferes with the ability to handle difficult social or intellectual tasks and behaviors during that time. At the same time, neurotransmitters signal the hippocampus (a nearby area in the brain) to store the emotionally loaded experience in long-term memory. In primitive times, this brain action would have been essential for survival, because long-lasting memories of dangerous stimuli (such as the large bear) would be critical for avoiding such threats in the future. Research also finds that during times of stress, nerve cells in the brain interpret chemical signals incorrectly. Instead of switching "off," these nerve cells perceive the signals as telling them to switch "on." It's as though the brain's "brakes" fail in response to stress. Response by the Heart, Lungs, and Circulation to Acute Stress The stress response also affects the heart, lungs, and circulation: * As the bear comes closer, the heart rate and blood pressure increase instantaneously. * Breathing becomes rapid, and the lungs take in more oxygen. * The spleen discharges red and white blood cells, allowing the blood to transport more oxygen throughout the body. Blood flow may actually increase 300 - 400%, priming the muscles, lungs, and brain for added demands. The Immune System's Response to Acute Stress The effect of the confrontation with the bear on the immune system is similar to mobilizing a defensive line of soldiers to potentially critical areas. The steroid hormones reduce activity in parts of the immune system, so that specific infection fighters (including important white blood cells) or other immune molecules can be repositioned. These immune-boosting troops are sent to the body's front lines where injury or infection is most likely to occur, such as the skin and the lymph nodes. The Acute Response in the Mouth and Throat As the bear gets closer, fluids are diverted from nonessential locations, including the mouth. This causes dryness and difficulty talking. In addition, stress can cause spasms of the throat muscles, making it difficult to swallow. The Skin's Response to Acute Stress The stress effect moves blood flow away from the skin to support the heart and muscle tissues. This also reduces blood loss in the event that the bear causes a wound. The physical effect is cool, clammy, sweaty skin. The scalp also tightens so that the hair seems to stand up. Metabolic Response to Acute Stress Stress shuts down digestive activity, a nonessential body function during short-term periods of hard physical work or crisis. The Relaxation Response: the Resolution of Acute Stress Once the threat has passed and the effect has not been harmful (for example, the bear has not wounded the human), the stress hormones return to normal. This is known as the relaxation response. In turn, the body's systems also return to normal. More Information on This Topic * Background * The Body's Response * Possible Complications * Conditions With Similar Symptoms * Treatment * Risk Factors * Lifestyle Changes * Resources * References * News & Features * Reporter's File * Expert Q & A * Questions for Your Doctor * Clinical Trials * 5 Things to Know View & Print In-Depth Report » Review Date: 1/30/2013 Reviewed By: Reviewed by: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch). A.D.A.M. Copyright The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2008 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited. SHARE Print E-MAIL Well Seller-Financed Deals Are Putting Poor People in Lead-Tainted Homes December 26, 2016 Is Early Retirement Great? For Some, It’s Hard Work to Have Fun December 23, 2016 The Night Girl Finds a Day Boy December 23, 2016 Should I Stay Silent During One Child’s Populist Taunt of Another? December 22, 2016 Statin Drugs Tied to Better Surgery Outcomes December 21, 2016 More Blog Headlines » Health & Fitness Tools BMI Calculator What's your score? » MOST POPULAR - HEALTH * E-Mailed * Blogged 1. After Weight-Loss Surgery, a Year of Joys and Disappointments 2. Well: The Scientific 7-Minute Workout 3. How to Find Clinical Trials for Experimental Cancer Treatments 4. In Cancer Trials, Minorities Face Extra Hurdles 5. Esther Wilkins, Who Set Standards for Dental Hygienists, Dies at 100 6. The New Old Age: You’re ‘Prediabetic’? Join the Club 7. Harnessing the Immune System to Fight Cancer 8. The Science of Fat: After ‘The Biggest Loser,’ Their Bodies Fought to Regain Weight 9. Well: Which Milk Is Most Nutritious: Soy, Cashew, Almond or Coconut? Go to Complete List » 1. Too Few Doctors in Many U.S. Communities 2. Deals to Keep Generic Drugs Off Market Get a Court Rebuff 3. Medicaid Expansion May Lower Death Rate, Study Says 4. Insurance Rebates Seen as Early Benefit of Health Care Law 5. Vote Looms in Massachusetts on Bill to Limit Health Care Costs Go to Complete List » Health Around the Web Powered by BlogRunner DCSIMG [&t=&s=0&ui=&r=&u=www.nytimes.com%2Fhealth%2Fguides %2Fsymptoms%2Fstress-and-anxiety%2Fthe-body%27s-response.html] [e621154bQ2FwwwwwwOwOZhQ5BQ25Q23Q25J)wwwwwwwwOQ23OSQ25wwg)wwwQ25Q5BQ23Z 9)Q2Fg] Campaign ID: 283468 | Creative: nyt2016_personalization_B2B_cookiesetter_v4 -- 414693 | Page: health.nytimes.com/health/guides/symptoms/stress-and-anxiety/the-body's -response.html / Targeted Page: health.nytimes.com/health/guides | Position: Inv2 * © 2016 The New York Times Company * Site Map * Privacy * Your Ad Choices * Advertise * Terms of Sale * Terms of Service * Work With Us * RSS * Help * Contact Us * Site Feedback Campaign ID: 283468 | Creative: nyt2016_personalization_B2B_cookiesetter_v4 -- 414693 | Page: health.nytimes.com/health/guides/symptoms/stress-and-anxiety/the-body's -response.html / Targeted Page: health.nytimes.com/health/guides | Position: Inv2