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Page 38 | Abby's Magazine - www.AbbysHealthAndNutrition.com amygdala, an area of the brain that contributes to emo onal processing. The amygdala interprets the images and sounds. When it perceives danger, it instantly sends a distress signal to the hypothalamus. Command Center When someone experiences a stressful event, the amygdala, an area of the brain that contributes to emo onal processing, sends a distress signal to the hypothalamus. This area of the brain func ons like a command center, communica ng with the rest of the body through the nervous system so that the person has the energy to fight or flee. The hypothalamus is a bit like a command center. This area of the brain communicates with the rest of the body through the autonomic nervous system, which controls such involuntary body func ons as breathing, blood pressure, heartbeat, and the dila on or constric on of key blood vessels and small airways in the lungs called bronchioles. The autonomic nervous system has two components, the sympathe c nervous system and the parasympathe c nervous system. The sympathe c nervous system func ons like a gas pedal in a car. It triggers the fight-or-flight response, providing the body with a burst of energy so that it can respond to perceived dangers. The parasympathe c nervous system acts like a brake. It promotes the "rest and digest" response that calms the body down a er the danger has passed. A er the amygdala sends a distress signal, the hypothalamus ac vates the sympathe c nervous system by sending signals through the autonomic nerves to the adrenal glands. These glands respond by pumping the hormone epinephrine (also known as adrenaline) into the bloodstream. As epinephrine circulates through the body, it brings on a number of physiological changes. The heart beats faster than normal, pushing blood to the muscles, heart, and other vital organs. Pulse rate and blood pressure go up. The person undergoing these changes also starts to breathe more rapidly. Small airways in the lungs open wide. This way, the lungs can take in as much oxygen as possible with each breath. Extra oxygen is sent to the brain, increasing alertness. Sight, hearing, and other senses become sharper. Meanwhile, epinephrine triggers the release of blood sugar (glucose) and fats from temporary storage sites in the body. These nutrients flood into the bloodstream, supplying energy to all parts of the body. All of these changes happen so quickly that people aren't aware of them. In fact, the wiring is so efficient that the amygdala and hypothalamus start this cascade even before the brain's visual centers have had a chance to fully process what is happening. That's why people are able to jump out of the path of an oncoming car even before they think about what they are doing. As the ini al surge of epinephrine subsides, the hypothalamus ac vates the second component of the stress response system — known as the HPA axis. This network consists of the hypothalamus, the pituitary gland, and the adrenal glands. The HPA axis relies on a series of hormonal signals to keep the sympathe c nervous system — the "gas pedal" — pressed down. If the brain con nues to perceive something as dangerous, the hypothalamus releases cor cotropin- releasing hormone (CRH), which travels to the pituitary gland, triggering the release of adrenocor- cotropic hormone (ACTH). This hormone travels to the adrenal glands, promp ng them to release cor sol. The body thus