Alcohol and its effects on the human bodies homeostasis; Perhaps you should pace yourself with those drinks...

Figure 1: Various brands of alcohol, all of which

able to alter the human bodies homeostasis.

Picture this… You're of legal drinking age, and you've just come out of a school/work week
packed full of tests and due assignments. The weekend has finally arrived and it's time to
party! You get together with friends and partake in the consumption of alcohol (figure 1). Fun
right? Well yes, but alcohol has other effects on the body than just increasing your confidence
and amusement. It actually has the ability to alter homeostasis, the regulation of body
conditions through the usage of feedback loops in living organisms. People often go for
cold drinks of ethanol to turn up after a long week of work, oblivious to its deep physiological
effects on our bodies (figure 2). Alcohol not only puts the liver into overdrive, but it can also
change water balancing methods, blood sugar levels, blood osmolarity, blood pressure and
even body temperature. You may want to pace yourself on your next night out, as large
quantities of alcohol can be dangerous. Here’s why.

Figure 2: A diagram of the human body, displaying where and what

effects alcohol can have on body conditions.

Homeostasis example...

When conditions are not in their optimal ranges, negative feedback loops can regulate them,
returning a certain body condition back to normal and keep the body in a constant state of
equilibrium. For example, glucose levels in blood often fluctuate based on one's diet (figure 3). In brief,
when blood sugar is too high, the beta cells in the islets of langerhans on the surface of the
pancreas will release insulin, a hormone that will allow glucose to enter cells to be used as fuel
as well as take excess glucose in the blood and transform it into glycogen to be stored in the
liver and muscle cells. This will bring blood sugar back to the optimal level as well as reduce
hunger, as no more sugars from food are needed. On the other hand, when blood sugar
drops, glucagon will be released by the alpha cells in the islets of langerhans on the surface
of the  pancreas and will break down glycogen and release it as glucose into the blood. This
will raise blood sugar to the optimal and trigger hunger as more sugars are needed. This is
one example of many loops that regulate conditions in the body.

Figure 3: A visual of the blood glucose level feedback loop, showing how a rise or drop in
blood sugar can be regulated by certain hormone releases.

As previously stated, alcohol has effects on many of the feedback loops in the human body. Some of
which you may even notice while drinking, which is why I've invited teens to ask about the effects of
alcohol and how, scientifically, they can be explained. Here is a Q & A section, where first time legal
drinkers ask questions about feelings and effects they have experienced with alcohol.

Q & A…

Q: Why is it that when under the influence of alcohol, urination seems to increase?

A: This is very common and relates directly to the water balance feedback loop (figure 4). Normally when
blood osmolarity/ pressure is too high, the pituitary gland located at the base of the brain will release ADH,
antidiuretic hormone produced by the hypothalamus, in order to increase thirst and permeability of the
collecting duct in the nephron, in turn increasing water retention and reabsorption in the kidneys. This
dilutes blood back down to normal and leaves a more concentrated urine. If blood pressure/
osmolarity drops too low, a different regulator pathway is taken. Alcohol actually inhibits the
production of ADH. This hormone is essential for the water reabsorption in the kidneys nephrons.
Without it, water retention decreases, making blood osmolarity/ pressure rise further above its optimal
range, which is very unhealthy. In turn, urine becomes very dilute and since minimal water is being
reabsorbed, it must be urinated out as waste. This explains the extra urinating while drinking alcohol as well
as the dehydration experienced in the days after drinking.

Figure 4: An example of the negative water balance feedback loop without alcohol altering it.
It shows how production of ADH will aid in the retention of water via kidneys.

Q: I often notice a feeling of warmth when drinking alcohol, how can this be?

A: Well, many young people refer to this warmth and fuzziness feeling as the beer blanket or the
vodka veil, etc. It's a common belief that this is directly related to body temperature homeostasis,
however that is not the case. No new heat is being produced when alcohol is consumed. Instead,
heat is moved around (figure 5). Alcohol causes blood vessels on the surface of your skin to dilate, attracting
warm blood from your body’s core to the exterior edges. The skins thermoreceptors sense the new
temperature and send signals to the brain, providing that comfy cozy feeling. This is why you feel as
though your body heats up due to alcohol. Note: This sense of warmth is not technically real and in
reality aids in cooling you down as all of your warm blood is closer to your body’s surface where heat
is released. So do be careful when making decisions under a beer blanket, especially in the winter
time where hypothermia is at risk.

Figure 5: Diagram showing the differences between normal and dilated blood vessels and how
when blood vessels are dilated, often due to alcohol, heat can be lost through the surface of the skin.

Thank you to the teens who submitted their questions.

The previous two symptoms of drinking alcohol are very short term, so lets shift our attention
to the long term fact that alcohol increases the risk of cancer in a human body. Studies have
shown that extreme consumption of alcohol has relations to thyroid, pancreatic and even
adrenal cancer. This relates heavily to the endocrine system and homeostasis as these
glands hosting cancer are what produce and release regulator hormones in order to regulate
the body and keep internal conditions at the proper level. Let's start with one of alcohols
positive effects, its decrease in the risk of thyroid cancer. One study stated that after testing
many different subgroups, based on age, gender, type of thyroid cancer and amount of
alcohol consumed, in general a decreased risk in thyroid cancer is highly associated with
alcohol intake (figure 6). This can be explained by alcohols effect on the hypothalamic-pituitary-thyroid
axis. Alcohol makes it less responsive and reduces its production of thyroid stimulating
hormone, the one that acts as a growth factor for thyroid nodules. Too much of this TSH is
known to increase the risk of thyroid cancer, therefore if alcohol is slightly decreasing its level
of production, it is in turn reducing the chances of developing thyroid cancer. In addition,
alcohol is slightly toxic to thyroid cells, therefore reducing the thyroids size and contributing
to a lower chance of thyroid cancer. In terms of hormone regulation, the thyroid produces
thyroxine and thyroid hormone, essential in the regulation of metabolism, heart rate, muscle,
brain and bone development. In summary, alcohol will reduce TSH in the body, decreasing
thyroid cancer risks but also having a negative effect on hormone regulation of many body
conditions since less TSH means less thyroxine and thyroid hormones.

Figure 6: This explains all of alcohols effects on the thyroid gland and its production of
hormones necessary in the regulation of body conditions and homeostasis.

Alcohol also has effects on pancreatic cancer. A study found that excessive alcohol use can
raise risk of pancreatic cancer in men (figure 7). This is no good for homeostasis as the pancreas is an
endocrine gland which carries insulin and glucagon producers on its surface. These hormones
are very necessary for regulating blood sugar, not allowing it to get too high or low. If cancer
affects ones pancreas, blood sugar control may be affected, putting the persons whole
system out of whack.

 Figure 7: Some information on the pancreas and pancreatic cancer. As shown on the bottom of the display, alcohol consumption is a leading cause in this type of cancer, which has effects on pancreatic hormone production.

And finally, alcohol has also been found to affect the endocrine system, more specifically the
reproductive function in males and females. A study states that the
hypothalamic-pituitary-gonadal axis is affected by alcoholism. Its main function is to produce
hormones necessary for reproductive function. When the HPG axis is not in a working state
due to the excessive alcohol amounts, sex drive, sex hormone production and fertility can all
be off balance. This affects reproductive hormone feedback loops and also has the ability to
alter secondary sexual characteristics such as body hair or size.

In the end, alcohol is a substance often introduced into our bodies that can have numerous
physiological effects on homeostasis. Our bodies self regulate against so many body condition
changes based on internal and external environments were exposed to, and alcohol is able to
affect this regulation. Its responsible for inhibiting the production of ADH, causing changes in
blood pressure, osmolarity, body temperature and water balance. Alcohol is also a substance
able to both increase AND decrease certain types of cancers. So, think twice before having
your next drink. It's always good to enjoy alcohol on a night out… but as with everything, it’s
best in moderation. Please drink responsibly (figure 8).
Figure 8: A message to all, implying that responsible drinking is the best drinking.