Video Transcript
Which of the following endocrine
glands are closely associated with the development of secondary sexual
characteristics? (A) The adrenal glands and the
pancreas, (B) the pancreas and the thyroid, or (C) the testes and the ovaries.
This question is asking us to
determine the function of specific glands in the human endocrine system. To do this, let’s take a quick tour
of the endocrine glands that have been mentioned in the answer options. This way, we can find out which
ones are closely associated with the development of secondary sexual
characteristics. And we can define some key terms
along the way.
Endocrine glands are groups of
specialized cells that are activated by certain changes in our bodies’ internal
environment. For example, some endocrine glands
are activated by an increase in blood glucose concentration. This triggers the cells within the
endocrine gland to produce specific chemical messengers called hormones. These hormones are then secreted
into the bloodstream. The blood then transports these
hormones all around the body, including to specific cells called target cells. Once hormones reach their
particular target cells, they can trigger a response in those cells to cause a
particular effect.
This diagram shows some of the main
endocrine glands in a human body, in a biological male on the left and a biological
female on the right. Let’s take a look at each of the
endocrine glands that have been mentioned in the answer choices and some of their
key functions. Humans tend to have two adrenal
glands, which sit above each kidney. They are responsible for producing
and secreting a huge range of hormones. One example that you’ve most likely
heard of is adrenaline. Adrenaline is involved in the
fight-or-flight response to help us react effectively to acutely stressful or
dangerous situations. The pancreas is located in the
abdomen, not far from the adrenal glands. And while it also secretes a huge
range of hormones, these hormones are different in their structure and function to
those released from the adrenal glands.
One example of a hormone that’s
released from the pancreas is insulin. Insulin is usually released when
blood glucose levels are too high. And it targets many different cells
in the body. The result of insulin’s action aims
to lower blood glucose back to within a healthy range.
The thyroid gland is a
butterfly-shaped gland located at the base of the neck. One of the thyroid hormones is
called thyroxine, or sometimes T4. Thyroxine has various target
tissues and multitudes of important functions. For example, it helps to control
our brain development and functioning, physical growth when we are children, and
plays a vital role in our metabolism.
The gonads, which are otherwise
known as the sexual or reproductive glands, are the only glands that differ
considerably between biological males and biological females. Biological females tend to have two
ovaries, while biological males tend to have two testes. The gonads in both males and
females secrete sex hormones. The testes tend to secrete larger
quantities of a sex hormone called testosterone, and the ovaries tend to secrete
larger quantities of a sex hormone called estrogen. However, both types of gland
release at least small quantities of all sex hormones.
The adrenal glands also release
some sex hormones. However, these are in much smaller
quantities than those released by the gonads. These hormones stimulate the
development of secondary sexual characteristics when a person reaches puberty. In males, this might include the
development of thicker facial and body hair, while in females it often involves the
development of breasts, among many other physical characteristics in both biological
sexes.
Now we’ve got enough information to
answer our question. The endocrine glands that are most
closely associated with the development of secondary sexual characteristics are (C),
the testes and the ovaries.
