要使内分泌系统能够适应生理需要,循环中的激素就得不断更新。这就得有一个清理活性激素的机制,它可能很快被清除(蛋白类激素大多只要几分钟),也可能需时较久(甲状腺素需经1周)。正像人们可能想到的,清除速度的快慢,与该内分泌腺对正常刺激作出适当分泌反应的速度快慢是平行的。多肽类激素在组织蛋白酶和肽酶作用下,在血浆中分解为其组成氨酸。激素被细胞摄取后(内部 To make the endocrine system to adapt to physiological needs, circulating hormones have to be constantly updated. There is a mechanism for cleaning up active hormones. It may be cleared quickly (most of the protein hormones take a few minutes) or may take longer (thyroid hormone takes one week). As one might expect, the rate of removal is parallel to the rate at which the endocrine gland will properly excrete the normal stimulus. Polypeptide hormones in the role of cathepsin and peptidase, in the plasma decomposition of its constituent amino acids. After the hormone is taken up by the cells (internal