Answer: Hormone
Explanation:
A hormone is a chemical substance produced in small quantities by an endocrine gland (such as thyroid gland in the neck) and carried in the blood to another tissue in the body where it acts as a messenger to control itsfunction.
Examples of hormones include:
- Thyroxine produced by the thyroid gland in the neck
- Testosterone produced by the testis in male humans
- Oestrogen produced by the ovary in female humans
