Throughout the body there are formations of special secretory tissues that form glands. Function of the glands is to produce and output hormones into the bloodstream. Hormones are transported to (sometimes) distant organs and tissues where they can act regulating various aspects of their metabolic activity.
The main human endocrine glands are :
- pituitary gland
- thyroid gland
- parathyroid glands
- islets of the pancreas
- adrenal glands
- placenta (during pregnancy)
Hormones are chemical messengers that maintain a perfect equilibrium
of numerous metabolic processes.
There are a few terms that need to be clarified :