Video Transcript
In this video, we’re going to
explore different diseases caused by the malfunction of some endocrine glands in the
human body. The hormones produced by our
endocrine glands are normally perfectly adjusted to our body needs. However, various factors that we
will outline together can make our endocrine glands malfunction. As we will see, even small
imbalances can have serious consequences on our health. Fortunately, in most cases,
treatments exist, and we will review some of them. But first, let’s briefly remind
ourselves about what an endocrine gland is and what it does.
An endocrine gland is usually a
group of cells that produce hormones. Hormones are chemical messengers
that are released in the blood and circulate through the entire body until they find
their target cells. Once inside the target cell, a
hormone can change the activity of that cell. This can cause it to use energy or
divide or to create other hormones, just to give a few examples. This way, hormones can adjust
different body functions and can adapt the changes in our environment. This constant adaptation of our
body to stay in balance is called homeostasis. Now, let’s look at some examples of
endocrine glands that contribute to our homeostasis.
We’ll first mention the pituitary
gland, which is a very important gland located under the brain. The pituitary gland regulates many
functions by releasing hormones that can either directly regulate certain cells in
our body or can indirectly regulate cells. Here, the pituitary gland can have
an effect on other endocrine glands to release hormones. These hormones can then act on
their target cells. Because the pituitary gland can
regulate other endocrine glands, it’s sometimes called the master gland.
One endocrine gland that’s
controlled by the pituitary is the thyroid gland. This is located in the front side
of our neck. The thyroid gland is one of the
largest glands in our body. It plays a major role in our
metabolism and our growth and development. It does this by releasing thyroid
hormones.
The pancreas is another important
endocrine gland of our body. When we eat food, the food can be
broken down into glucose, which is then released into the blood. The pancreas can then release
hormones to control the blood glucose levels. If these levels aren’t controlled
by the pancreas, then our blood glucose levels can rise too much and this can be
very dangerous. As a consequence, too little or too
much of these hormones, either from the pancreas or another endocrine gland, can
disrupt homeostasis. This can result in serious health
problems, making us develop a range of diseases, sometimes with long-term
consequences.
Let’s review several examples of
these disorders, starting with one disorder caused by the dysfunction of the
pituitary gland. But first let me ask you, have you
ever heard of the footballer Lionel Messi? He is considered one of the best
players of all time. Messi managed to become this
amazing footballer, despite being diagnosed with the disorder called growth hormone
deficiency, also sometimes called pituitary dwarfism at the age of 10. How does this disease manifest
itself?
Growth hormone, or GH for short, is
a hormone produced by the pituitary gland throughout our lifetime. When we are children and teenagers,
it plays an important role on our growth and development of our bones and
muscles. This is because GH stimulates our
cells to divide and regenerate. Sometimes because of a genetic
mutation or cancer, for example, the pituitary may not produce GH effectively. In children, this stops them from
growing, while in adults this may cause loss of muscle mass or bones to weaken.
Fortunately, there is a treatment
that can correct this. The treatment consists of injecting
human GH into the patients. In the past, this GH was obtained
from deceased donors. Nowadays, human GH can be produced
from genetically modified bacteria. In these bacteria, the human gene
that makes GH is inserted into the DNA of the bacteria. When this happens, the bacteria can
make a lot of GH that can be collected. This can then be safely injected
into patients to correct the growth hormone deficiency.
Sometimes, a pituitary gland
malfunction can also lead to an increase in GH. When too much GH is produced during
childhood, this causes the long bones to grow further, resulting in a condition
called gigantism. Children with gigantism can grow up
to two meters or more in height. The most common cause of gigantism
is a noncancerous tumor on the pituitary gland. Treatment of gigantism usually
involves the destruction of the tumor using lasers. This stops the overproduction of
GH. As we’ve just seen, the
consequences of an imbalance of GH can impact many different types of cells. Similarly, the hormones secreted by
the thyroid gland influence many cells as well. Let’s have a look at diseases
caused by thyroid gland malfunctions.
The thyroid gland produces
hormones, for example, thyroxine. Thyroxine can control how quickly
our body uses energy, how fast proteins are produced, and how our brain develops and
functions. Both over- and undersecretion of
thyroxine can cause the gland to enlarge. An enlarged thyroid gland is called
a goiter. The thyroid gland is controlled by
a hormone called TSH, or thyroid stimulating hormone. This is released by the pituitary
gland. In addition to being controlled by
the pituitary gland, the thyroid gland needs the mineral iodine to function
properly. We mostly get iodine from our diet,
mainly from seafood, dairy, eggs, or table salt. If your diet doesn’t include enough
iodine, then your thyroid gland will be less able to produce thyroxine.
When thyroxine levels are low, the
pituitary gland increases production of TSH. This can lead to a buildup of TSH
in the thyroid gland. This causes the thyroid gland to
become enlarged and form a simple goiter. Because thyroxine levels are low,
less energy is available for a body to function properly, muscle mass can decrease,
and normal brain function is impaired. This can cause intellectual
disabilities in children or can slow down the brain functions in adults. The lack of thyroxine can be
corrected by eating more food that contains iodine or by taking medicine to replace
these hormones.
So, this is what happens when
thyroxine levels are low, but what about when they’re high? The thyroid gland can also
malfunction to produce high levels of thyroxine. This is often caused by the immune
system mistakenly attacking the thyroid gland. The thyroid gland can then become
swollen and form a goiter like before. However, this is called an
exophthalmic goiter because the immune system can attack the tissue around the eyes,
causing them to appear bulging. Exophthalmic is a medical term that
describes protruding eyes. Too much thyroxine can cause the
body to produce and use more energy. This can lead to weight loss and
improper muscle function. To correct this, a part of the
thyroid can be surgically removed to reduce thyroxine overproduction. In addition, changes to the diet to
reduce iodine might help.
Now, let’s talk about disease of
the pancreas. When we eat food or have a sugary
drink, it’s broken down into glucose. This glucose is dissolved in the
blood. And if we measure blood glucose
levels, we can see that its concentration peaks after about an hour. This glucose is very important and
is used by cells like muscle cells to produce energy. But these cells can’t absorb
glucose unless a special hormone called insulin is present. Insulin is produced by the
pancreas. The pancreas is able to detect
glucose levels. And when they’re high, the pancreas
will produce more insulin. This way, the cells can absorb
glucose for energy. So glucose peaks after about an
hour of having a sugary drink. Then, insulin is produced, which
allows the cells to absorb glucose. So, glucose levels drop over the
next few hours.
This is what happens in a healthy
individual. However, in those with diabetes,
these glucose levels stay higher for a longer period of time. This is because the pancreas isn’t
functioning properly and can’t produce enough insulin. Without enough insulin, the cells
aren’t able to take up as much glucose. And so, glucose levels rise and
take longer to go back down.
There’s two types of diabetes: type
one and type two. In type one, the cause isn’t clear,
but maybe due to the immune system mistakenly attacking the healthy tissue of the
pancreas, while in type two diabetes, the cells of our body become resistant to
insulin. This usually occurs later on in
life. This excess glucose in the blood
causes many symptoms of diabetes, such as increased thirst and urine output, as well
as being tired more frequently. Some of the long-term effects
include heart problems, strokes, and nerve damage. So, monitoring glucose levels and
administering insulin is important in these individuals.
Now, let’s take a moment to go over
a practice question.
The figure shows how the thyroid
gland can become enlarged, forming a goiter. What nutrient deficiency may lead
to the formation of an enlarged thyroid, as shown in the figure?
The thyroid gland is one of the
largest glands of the endocrine system. This gland, which is found in your
neck, is controlled by the pituitary gland found in the brain. The thyroid gland produces the
hormone thyroxine. This controls how quickly your body
uses energy, the speed of protein production, and brain development and
function. When thyroxine levels are low, the
pituitary gland tries to stimulate more by releasing a hormone called TSH, or
thyroid stimulating hormone. In some cases, the thyroid gland
may not be functioning properly, and this can lead to a buildup of TSH. This can cause the thyroid gland to
become enlarged and form what’s called a goiter.
In addition to being controlled by
the pituitary gland, the thyroid gland needs the mineral iodine to function
properly. However, the body does not produce
iodine, so the only source of it is from the food that we eat. If the diet is low in iodine, the
thyroid gland will be less able to produce thyroxine. This can lead to a buildup of TSH
and can form a goiter. Therefore, a nutrient deficiency of
iodine can lead to a goiter.
Now, let’s go over the key points
that we covered in this video. Some diseases are caused by a
malfunction of endocrine glands. Malfunction of the pituitary gland
can lead to a lack of GH, which causes dwarfism, or excessive GH, which causes
gigantism. Dwarfism can be treated by
injection with GH. Malfunction of the thyroid gland
can lead to a lack of thyroxine, which causes a simple goiter, or excessive
thyroxine, which causes an exophthalmic goiter. A simple goiter may be treated by
getting more iodine in your diet. Malfunction of the pancreas can
lead to a lack of insulin and cause the disease diabetes. This can be treated by insulin
injections.
