See also

Note:
Pinyin#Pinyin tone marking

Hormones are the chemical messengers of the endocrine system. Hormones are the signals, together with the nervous system, adjust the body's internal working. Each multicellular organism has hormones. The cells of different organs have specialized receptors to response to a particular hormone. When a hormone touches to the protein of the receptor, a communication mechanism is activated. The cell or tissue that gets the message is called the "target." Hormones only act on cells which have specified receptors.

Jīsù shì nèifēnmì xìtǒng de huàxué xìnchāi. Jīsù shì yǔ shénjīng xìtǒng gòngtóng tiáozhěng tǐnèi gōngzuò de xìnhào. Měigè duōxìbāo shēngwùtǐ dōu yǒu jīsù. Bùtóng qìguān de xìbāo dōu yǒu zhuānmén jiēshōuqì duì tèdìng de jīsù yǒu fǎnyìng. Dāng jīsù jiēchù dào jiēshōuqì de dànbáizhì shí, tōngxùn jīzhì jiù qǐdòng. Dédào xìnxī de xìbāo huò zǔzhī chēngwéi “mùbiāo”. Jīsù zhǐ duì jùyǒu tèdìng jiēshōuqì de xìbāo cái qǐ zuòyòng.