Biology Question -- Please HELP!

[Josh]

Question:
Why are nonendocrine messengers not considered to be hormones?

 

[Recneps]

<<Why are nonendocrine messengers not considered to be hormones? >>

Because the endocrine system is a system which produces hormones. There for endocrine = hormones so nonendocrine != hormones. If you would like a better answer post a better question.

 

[BlueScreenVW]

Also, which kind of messengers do you refer to? For example:

Transmittor substances (CNS, PNS) <--- Sometimes called &quot;neurohormones&quot;
Intracellular messengers (cAMP, Calcium)
Feromones
Etc...

Actually, one &quot;definition&quot; of a hormone is that it reaches (almost) the whole body by the blood. Thus, it must be endocrine. As opposed to paracrine, autocrine, etc.

 

[kimagurealex]

easy, because only endocrine messengers are considered hormone.

 

[kimagurealex]

haha, answering the question with the question.

 

[JACKHAMMER]

It all depends on what type of &quot;hormone&quot; you are talking about. You specifically mention endocrine (by blood) but as stated above there are numerous other extrcellular messengers. BY strict definition a hormone is only endocrine (made by an endocribe tissue into the blood stream and influences a target tissue). Other extracellular messengers like many steroids, etc. are not hormones by the strictest definition although their function maybe the same as true hormaone.

 

[Josh]

Yea, I got the answer. Thanks anyway guys