Define the following: (a) Exocrine gland (b) Endocrine gland (c) Hormone
The provided context does not explicitly define exocrine glands, though it mentions that the pancreas acts as both exocrine and endocrine gland.
Endocrine glands lack ducts and are hence, called ductless glands. Their secretions are called hormones.
Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts.
Explanation
The provided textbook context explicitly defines endocrine glands and hormones in Section 19.1. For endocrine glands, the text states they 'lack ducts and are hence, called ductless glands'. For hormones, the text provides a current scientific definition stating they are 'non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts'. However, the context does not provide a definition for exocrine glands; it only mentions the pancreas acts as one in Section 19.2.8. Therefore, the answer for (a) is limited to the information available in the text.