Catecholamine and Internal secretion

Catecholamine noun - Any of a group of chemicals including epinephrine and norepinephrine that are produced in the medulla of the adrenal gland.

Internal secretion and catecholamine are semantically related. In some cases you can use "Internal secretion" instead a noun "Catecholamine".

Internal secretion noun - The secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect.

Catecholamine and internal secretion are semantically related. Sometimes you can replace term "Catecholamine" with "Internal secretion", this terms are similar.