What are the relationships between hypothalamic hormones (releasing and inhibiting), pituitary (tropic hormones), and end hormones?

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Hormones are small molecule chemical messengers in the body.  They are secreted from different glands in the body that make up the endocrine system.  The hormones travel through the body to their intended targets to help control bodily functions like growth, digestion, and sexual responses.

Hypothalamic releasing hormones are neurological based hormones that are produced by the hypothalamus, which is a particular part of the brain that connects the nervous system to the endocrine system.  These releasing hormones are responsible for triggering the pituitary gland (a small gland at the base of the brain) to release different hormones that control a wide variety of functions, including growth, sexual functions, and sleep/wake cycles.  Hypothalamic inhibiting hormones function similar to releasing hormones but instead of triggering the release of a new hormone by the pituitary gland, they trigger the inhibition of the production of a particular hormone from the pituitary gland.

Tropic hormones are similar to hypothalamic hormones in that they target the production of other hormones in other glands.  Unlike hypothalamic hormones, they tend to originate from the pituitary gland and target other glands throughout the body, including the thyroid, sexual glands, and liver.

I have actually never heard of the term "end hormone" nor can I find any reference to it online.  I'm not sure if that is an actual biological term or if perhaps you mistyped your question.  Since all of the other hormones that we have been talking about have been tropic in nature (that is, they act on other glands to produce other hormones rather than acting on individual tissue cells directly themselves), I'm guessing that perhaps you are referencing non-tropic hormones.  These are hormones that directly act on specific target tissue cells to induce a response.  In this way, they can be thought of as "end" hormones since they go directly to the end of the signalling chain themselves.

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