Endocrine products (hormones) are released directly into blood rather than through ducts
Endocrine system includes specialized glands known as endocrine glands. These glands secrete their products, hormones, directly into the blood rather than through a duct. The main endocrine glands include the adrenal, thyroid, pituitary gland, thymus and pancreas. Ovaries and testes are also considered as endocrine glands. The hypothalamus is a neuroendocrine organ. Other organs which are not so well known for their endocrine activity include the stomach, which produces hormones such as ghrelin. Local chemical messengers, not generally considered part of the endocrine system, include autocrines, which act on the cells that secrete them, and paracrines, which act on a different cell type nearby.
Hormones play a very important role right from the birth to development
Hormones depends on the presence of receptors to respond to a target cell. These receptors are present within the cell or its plasma membrane, to which the hormone can bind. Hormone receptors are dynamic structures.
Hormones play a very important role in our life right from our birth by regulating reproduction, growth and development in many ways and help maintain homeostasis. The moodiness of teenagers, obesity of humans and even the transformation of caterpillar into a butterfly are regulated by hormones. Millions of people with diabetes all over the world take the hormone insulin. Hormones are also used in cosmetics to keep the skin smooth and in livestock feed to fatten cattle. So our life style, moods and emotions are also influenced by the hormones. The activities in our body are highly complex and they need to be so regulated that every activity takes place at a proper time and in a correct sequence. For example, the gastric juice, bile and pancreatic juice should be poured into the food canal only when there is food in it. Though this kind of regulation is done to some extent by the nervous system but it also brought about by hormones.