What type of organ secretes hormones?

Do all organs of our body secrete hormones?

My teacher says that all organs of our body secrete some kind of hormone so they are all glands. Is the statement entirely correct without any exceptions? Till date I am unable to find any exception for that statement. Could anybody provide an exception if any present?

$\begingroup$ Oesophagus contain adipose tissue which secretes hormones like leptin, adiponectin and resisting. $\endgroup$

$\begingroup$ How do you define an organ? Paracrine signalling factors are not considered hormones. If you consider interferons and chemokines as hormones, then cells that secrete these are found almost everywhere. $\endgroup$

1 Answer 1

Good question! The major and most common endocrine glands in the human body include pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, gonads and pineal gland, along with neuroendocrinol glands like hypothalamus. Some other, not-so-common, examples include heart (Anti-Natriuretic Factor), GI tract organs (gastrin, secretin, etc.), placenta (estrogen, progesterone, etc.), kidneys (erythropoietin, renin), skin (cholecalciferol) and adipose tissue (leptin) 1 . Even the lungs are known to secrete calcitonin 2 .

In spite of this, I can think of quite a few examples of organs which do not act as endocrine glands. That is because there is a difference between the organs secreting hormones and endocrine glands. The definition of endocrine glands is as follows 1, 5, 6, 7, 8 :

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct.

So, if these organs don’t directly secrete the hormones into the bloodstream, then they are not endocrine glands. Leading this way, emotional tears are known to consist of hormones such as prolactin, ACTH and leucine-enkephalin 3, 4 . Thus, though eyes do secrete hormones, they are not endocrine glands. Also, not sure about this, but lungs still do not seem to fit in the category of endocrine glands.

In short, all the organs of the body might secreted hormones, but they all cannot be considered as endocrine glands.