As college students, we are very familiar with attempting to manage copious amounts of stress. From studying, to taking exams, to finding time to eat lunch, it seems as though we can never catch a break. However, we are definitely not the only animals that experience this horrible feeling. In fact, the mechanisms behind stress responses are similar among all vertebrates. The Human Stress Response It is Sunday night. You have a lab report due tomorrow, a Biology exam on Tuesday, and a research paper for English due Thursday. You are stressed to the max. On the outside, you try your best to stay cool, calm, and collected, but on the inside, hormones are surging. The hypothalamic-pituitary-adrenal (HPA) axis has been activated, signaling neurons in the hypothalamus to release corticotropin-releasing hormone (CRH). Another hormone, adrenocorticotropin (ACTH), is released from the pituitary gland into the bloodstream, where it reaches the adrenal glands that are located above the kidneys. This triggers the secretion of “stress hormones”: cortisol and the catecholamines (epinephrine and norepinephrine). These hormones signal the fight-or-flight response, in which we experience the all-too-familiar increase in heart rate and blood pressure. It is possible to quantify amounts of these hormones using blood, urine, and saliva. Salamanders get stressed out, too!?! Salamanders may not have exams to worry about, but they experience stress regularly. As the most abundant vertebrate group in the southeastern United States, salamanders play an important role in the ecosystem. However, increases in temperature, decreases in moisture levels, predicted habitat loss, and the possibility of disease threaten the wellbeing of salamanders. The ultimate goal of this project is to understand how these stressors affect the physiological stress response of the Southern gray-cheeked salamander, Plethodon metcalfi. When an amphibian is exposed to a stimulus that disrupts homeostasis, such as high temperature, its body reacts by adjusting metabolic rates. This may be a result of the activation of the hypothalamus-pituitary-interrenal (HPI) axis, which signals the release of glucocorticoid molecules and corticosterone. Corticosterone is a stress hormone that circulates through the bloodstream and increases in concentration as the amphibian faces a stressful event. Subsequently, blood glucose concentrations also increase, allowing the amphibian to change its behavior and immune response, and therefore, alleviate the effects of the stressor. So...next time you're stressed out, just remember that you're in very good company. ~Samantha
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The Slime Times is written by the Stress After Dark Creative Inquiry TeamScience isn't all white lab coats and ivory pillars, sometimes you just need to get slimy. Archives
August 2016
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