HPA Axis Essay

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1. What is the function of the HPA Axis and why should someone with Type-A personality be concerned about the effects of HPA Axis activation? (20 points) The HPA Axis also known as the Hypothalamic Pituitary Adrenal Axis, is a complex set of direct influences and feedback interactions among the hypothalamus (a part of the brain that controls visceral systems involved in fight or flight reactions). The hypothalamus regulates neural controls, the basic biological functions that include tasks that regulating hunger, thirst, temperature, sexual arousal, and is also involved with emotions. It also includes the pituitary gland (the master gland connected to the hypothalamus), and the adrenal glands (glandular-hormonal control). The interactions among these organs constitute the HPA axis. A major part of the neuroendocrine system controls reactions to stress and regulates many body processes such as digestion, the immune system, mood and emotions, sexuality, and energy storage and expenditure. The main hormones that activate the HPA Axis are corticotrophin-releasing factor, vasopressin, and adrenocorticotropin hormone. It is completed by the negative feedback of cortisol on the hypothalamus and pituitary. Cortisol negatively affects the immune system and prevents the release of immunotransmitters. Release of CRH from the hypothalamus is influenced by stress and by blood levels of cortisol. Increased production of cortisol signals an alarm reaction to stress, facilitating an adaptive phase of a general adaptation syndrome in which alarm reactions including the immune response are suppressed, allowing the body to attempt countermeasures. When psychosocial stressors occur, a sequence of events called a neural cascade begins. Higher cortical and limbic system analysis defines the stressor internally as a threat that requires a response. Signals sent to the
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