Hormones

These are chemical messengers or information molecules which are produced by ductless glands and transported by circulatory system to other parts of body for inducing and coordinating their activities,

Characteristics:

1. These are produced by endocrine glands and poured into circulatory system
2. These act on specific cells , tissues and organs called target sites away from the place of origin.
3. Since these are transported by blood , their action is slow( except adrenaline)
4. These are small sized molecules of diverse origin-proteins, peptides, amino acid, steroids etc.
5. They are effective in very low concentration.
6. They are generally produced in response to a stimulus and are consumed during their activity in target cells.
7. Both their deficiency and excess is harmful.

Glands:

A cell, tissue or an organ that produces a secretion for performing a particular function is called gland. These can be 

1. Exocrine glands:These drain out their secretion through ducts into target sites which are adjacent to the gland. The secretion can be enzymes, mucus, excretory substances etc. Example:gastric glands, milk glands, sweat glands.
2. Endocrine glands: These are isolated glands which do not have ducts for draining out their secretion but put it into blood as their target sites are away from the point of origin.Their secretion comprises of hormones. Eg: Thyroid, pituitary gland.
3. Heterocrine glands: They have both exocrine and endocrine regions.Eg:Pancreas.