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Long-term and short-term mechanisms that control blood pressure are one of the most important issues of medical physiology. According to Khurana (2008, p. 188) every mechanism has its own specific function. The author states that the control of BP is performed under physiological conditions, and a narrow range of 95 to 100 mmHg is the normal mean arterial pressure (MAP). Short-term mechanisms are also called rapid ones; they include baroreceptor reflexes, central nervous system ischaemic response, and chemoreceptor reflexes. The salient features of those reflexes which belong to short-term mechanisms include their rapid action, i.e. “within seconds to few minutes of alterations in blood pressure” (Khurana, 2008, p. 188). Also, the period of these short-term mechanisms’ work varies from a few hours to a few days so that they are insignificant for long-term mechanisms which control blood pressure. Moreover, these reflexes are useful in “preventing acute diseases in blood pressure” (Khurana, 2008, p.188). Sherwood (2012) avers that “long-term regulation of blood pressure rests with the kidneys and the thirst mechanism” (p. 554). Khurana (2008, p. 189) divides long-term mechanisms into direct and indirect ones. Direct mechanisms include a kidney which controls circulatory volume while indirect mechanisms comprise functioning of a kidney via hormonal mechanisms. Rhoades and Bel (2012, p. 317) state that epinephrine which is from adrenal medulla, AVP (antidiuretic hormone), rennin, and ANP influence blood pressure. The most important ones are epinephrine which rises BP and rennin which is released by kidneys and lowers BP. For example, in case of an extreme situation, one’s BP is higher because of the release of adrenaline. During blood loss, rennin is usually released even before BP becomes lower.
To sum up, it is necessary to admit that long-term and short-term mechanisms of control play an integral role in circulatory system. This control can be performed either by reflexes or hormonal mechanisms. Today, numerous scientists are conducting a study of circulatory system and all types of mechanisms which control it. These studies make treatment of various diseases more successful.