Physiological Consequences of External Stressors

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This essay sets out to discuss the physiological consequences of external stressors on the body, with particular attention to the impact that they have on the Nervous, Endocrine and Cardiovascular systems. External stressors could be described as any physical or emotional strain such as those brought on by fear, exercise, illness, negative relationships or poor living conditions (UMMC, 2011) The human body is naturally equipped with a built in mechanism which provides a biochemical reaction that adapts and responds to stress, and this is referred to as the ‘Fight or Flight Response’ (Harari & Legge, 2001: 75). The two main controllers of the stress response are the Sympathetic Nervous System (SNS) and the Hypothalamic-pituitary-adrenal (HPA) Axis. Responding to biochemical and environmental demands, both these systems work together in tandem via a feedback loop and are responsible for ensuring timely control and activation of physiological responses and maintenance of homeostasis throughout the body (Tortora & Derrickson, 2012: 713-714). The first stage of the stress response occurs when the hypothalamus in the brain detects stress and switches on the Sympathetic Nervous System (SNS) to induce a rush of adrenaline. The (SNS) activates body functions involved in the stress response by releasing Noradrenaline via the sympathetic nerves and Adrenaline and Noradrenaline via the Adrenal Medulla. These neurotransmitters work to increase heart rate, blood pressure, cellular metabolism and bronchial dilation with a view to ensuring that adequate oxygen, nutrients and energy supplies are delivered to essential organs in preparation for an emergency response. Moreover, these chemical messengers are also responsible for vasoconstriction of blood vessels which inhibit the functioning of the digestive system; this prevents blood from being diverted from essential

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