Video Transcript
With reference to the human endocrine system, which of the following best defines the term hormone? A hormone is a biological catalyst that is used by the body to speed up the rate of chemical reactions. A hormone is an electrical impulse that is transmitted from an endocrine gland to specific cells in the body via the nervous system. A hormone is a form of neurotransmitter that is used to communicate between different nerve cells. A hormone is a chemical messenger that is transported from endocrine glands to target organs via the bloodstream.
To answer this question, let’s review some key facts about the human endocrine system and its main messengers, hormones. The human endocrine system is made of endocrine glands, which produce and secrete chemical messengers that the body uses for a range of functions. The major glands of the endocrine system include the pituitary, the pineal, the thyroid, the thymus, the adrenal, the pancreas, ovaries, and the testes. Each of these glands produces and secretes chemical messengers called hormones.
Hormones are chemical messengers that travel throughout the body via the bloodstream to target cells and organs. Let’s take a look at this process. When a change in the body activates endocrine glands, hormones are secreted directly into the bloodstream. Once in the bloodstream, hormones are able to travel throughout the body. Hormones are able to leave the bloodstream and act upon target cells or target organs and cause an effect. However, since hormones travel via the bloodstream, the effect of hormones may take minutes or even days to occur.
With this information, we can now answer our question. So, with reference to the human endocrine system, the statement that best defines a hormone is a chemical messenger that is transported from the endocrine glands to the target organs via the bloodstream.
