Expert: Walter Hintz - 12/9/2006

Question
HI!
  I'm a 17 years young boy from Pakistan studying in pre-medical and i want to know that how do that harmones reach to thier target organs or sites? Are these controlled by brain in animals and how these are controlled by plants? Sir this not my home work question, i'm telling you this because i asked from one scholar here at allexpets.com but he reply that he could not answer my home work questions but that's not so. Hope to get a proper and stisfactory answer from your side.

Answer
 Hi Isras
Hormones are secreted directly into the blood stream and reach the organs through circulation.  All organs are reached but the action of each hormone is directed only to specific organs.  The nervous system is involved in secretions and there are feedback mechanisms that  also control secretions.  Adrenal hormones for example are controlled by secretions from the pituitary gland.
I cannot help you with respect to plant hormones.  You can probably google this topic.
  Most experts on this site will not answer homework questions especially test questions.