How is communication among parts of an organism accomplished?

Transported by blood they reach target organs, i.e., organs for which they are intended.
(b) Hormones may stimulate or inhibit specific biological processes in target organs to modify their activities. Thus they regulate organs and tissues.
© The activity of these messenger molecules, i.e., hormones secreted in the blood by endocrine glands is under the direct control of the nervous system.
They have a central role in body activity because they influence various functions like coordination and response to various internal and external stimuli.
(e) There is considerable coordination between nerves and hormones and functional hormonal co-ordination play an important role in communication among all parts of the body.