Read the passage given below and answer the following questions from (i) to (v).
Hormones act as chemical messengers that are released into the blood stream to act on an organ in another part of the body. Endocrine systems, also referred to as hormone systems, are found in all mammals, birds, fish, and many other types of living organisms. They are made up of: (a) glands located throughout the body, (b) hormones that are made by the glands and released into the bloodstream or the fluid surrounding cells, and (c) Receptors in various organs and tissues that recognise and respond to the hormones.
(iv) In humans, the timing and amount of hormone released are regulated by:
(2)