a) Where does the name 'endocrine gland' come from?

The name 'endocrine gland' comes from the Greek words 'endo' and 'krinein'. 'Endo' means 'within' and 'krinein' means 'to separate' or 'to secrete'. So, the term 'endocrine' essentially refers to the internal secretion of substances. Endocrine glands secrete hormones directly into the bloodstream rather than through a duct, which is why they are also known as ductless glands.