Video Transcript
Which of the following is not a function of hormones in the human body? (A) Helping maintain a constant internal environment. (B) Stimulating the development of secondary sexual characteristics. (C) Regulating metabolic functions. Or (D) Transmitting electrical signals between neurons.
Since this question asks us to identify what is not a function of hormones in humans,
let’s first review what hormones do within the human body, and eliminate the choices
that contain actual functions of hormones.
Hormones are the chemical messengers of the endocrine system. This organ system is composed of glands throughout the body that secrete hormones
into the blood that can then be carried to target cells elsewhere in the body. Through the action of hormones, the endocrine system regulates many important
biological processes such as metabolism, reproduction, and heart rate. Let’s look at a few examples.
Follicle-stimulating hormone stimulates the gonads, or sex organs, to produce mature
eggs in females and sperm in males. Luteinizing hormone will also influence these organs. In females, this hormone stimulates ovulation, or the release of a mature egg from
the ovary. In males, luteinizing hormone aids in the production of testosterone. Testosterone stimulates the development of secondary sexual characteristics like
beard growth and voice deepening. So, one function of hormones is to stimulate development of secondary sexual
characteristics. Therefore, we can eliminate (B).
Follicle-stimulating hormone and luteinizing hormone are released from the pituitary
gland in the brain. This gland is often called the master gland because it controls many other endocrine
glands through the stimulating hormones it releases. For example, the pituitary gland also releases a hormone to stimulate the thyroid,
which releases its own hormones to regulate metabolic processes, which affect weight
and energy levels. Since we have an example of a hormone that regulates metabolic functions, we can also
eliminate (C).
Some other well-known hormones include insulin and glucagon, which are released by
the pancreas. These hormones regulate blood sugar levels. When blood sugar is too low, glucagon is released to promote the release of stored-up
sugar, or glycogen. When blood sugar gets too high, insulin is released to transport the sugar out of the
blood and bring the blood sugar levels back down. In this way, these hormones work together to maintain a more or less constant,
optimal blood sugar level, not too high and not too low. Since we have an example of hormones helping to maintain a constant internal
environment, we can also eliminate (A).
However, there are no hormones that transmit electrical signals between neurons. Chemical substances that transmit such messages are called neurotransmitters. Remember that hormones are chemical, not electrical. And they are released into and carried by the blood, not neurons. Therefore, the correct answer to this question is (D). Something that is not a function of hormones in the human body is transmitting
electrical signals between neurons.
