Define the following:
(a) Exocrine gland , (b) Endocrine gland, (c ) Hormone

Explanation

(a) Exocrine Glands
Glands that discharge secretions into ducts are known as exocrine glands. Sebaceous gland in the skin, salivary galnd in the buccu cavity, etc. ectopic collections of sebaceous glands in oral cavity are celled Fordyce granyles are examples of exocrine glands.
(b) Endocrine Glands
Glands that do not discharge their secretions into ducts are knwn as endocrine glands . Instead, these glands discharge their secretions directly into the blood. Pituitary gland, thyroid gland, adrenal gland, etc. are examples of endocrine glands.
(c) Hormones
Hormones are chemical messenger that regulate physiological processes in living organisms. They act upon specific cells/tissues/organs which are called target cells/tissues/organs