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激素（希臘語 hormaein：刺激）是一種由內分泌（希臘語 endocrine）腺所產生的化學物質。它們進入血液並且在體內調節各種各樣的生理過程。激素所涉及的人體的性方面，下列三種內分泌腺特別的重要：1.垂體；2.女性和男性性腺（卵巢或睾丸）；3.腎上腺。

1.垂體 是一個位於腦的下方的約花生大小的器官，它分泌刺激其他腺體的激素，例如性腺。由於這個緣故，它也被稱為“主腺”。

2.性腺 卵巢分泌雌性激素和黃體酮，俗稱“女性激素”。睾丸分泌雄性激素，俗稱“男性激素”。

3.腎上腺 也分泌上述部分性激素。
 

Hormones (gr. hormaein: to stimulate) are chemical substances produced by internally secreting (gr. endocrine) glands. These substances enter the bloodstream and stimulate various processes inside the body. In the context of human sexuality, the following three endocrine glands are especially important: 1. the pituitary gland, 2. the female or male gonads (ovaries or testicles) and 3. the adrenal glands.

1. The pituitary gland is a peanut-size organ located beneath the brain, and it produces hormones which stimulate other glands, for example, the gonads. For this reason, it is also sometimes called the "master gland".

2. The gonads:
The ovaries produce, a.o. the so-called 'female' hormones estrogen and progesterone.
The testicles produce a.o. the so-called 'male' hormone testosterone.

3. The adrenal glands also produce a small portion of all of these hormones.