Hormone secretion is regulated by four different mechanisms: hormone levels, hormone effects, levels of circulating substance, and circadian rhythms.
- Hormone levels feed back to the pituitary and hypothalamus for hormones that are regulated by tropic hormones (such as thyroid hormones and cortisol).
- Hormone effects, such as stress, feedback to the CNS causing sympathetic activation and release of epinephrine from the adrenal medulla.
- Levels of circulating substance feedback to specific endocrine gland (such as the response of insulin to blood glucose levels).
- Circadian rhythms release hormone according to a daily pattern (for example, cortisol peaks mid-morning).
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