Chapter 4: Stress Management and Sleep 75 Stress Response There are three stages to the stress response: alarm, resistance, and exhaustion (Selye, 1974). The first stage of the stress response is called the alarm stage or the fight-or-flight stage. In the alarm stage, the hypothalamus stimulates both the pituitary gland and sympathetic nervous system (part of the nervous system responsible for providing a rapid and involuntary response to dangerous or stressful situations). The pituitary gland responds by releasing adrenocorticotrophic hormone (ACTH), which in turn stimulates the adrenal glands. The adrenal glands respond by releasing the hormones cortisol, epinephrine, and norepinephrine into the blood. Collectively, these hormones and the sympathetic nervous system produce a heightened state of physical awareness. Some of the physiological responses to stress include increases in blood pressure, heart rate, respiratory rate, blood flow to the muscle as well as activation of the sweat glands (Johnson & Morris, 2012). These responses are depicted in Figure 4.4. Figure 4.4. The Physiological Response to Acute Stress
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