Have you ever find yourself sitting in a library when, all of a sudden, you start hiccuping loudly? This happened to a friend of mine the other day and I found myself thinking, why do we hiccup? What happens in our body when we do hiccup?

What is hiccuping and how does it work? 

Hiccuping results from uncontrollable spasms of the muscles that help us breathe. These muscles include our diaphragm (which is considered the major player of this response), the muscles between our ribs (intercostal muscles) and the muscles in our neck1. Our diaphragm sits under our lungs and above our stomach. Hiccuping forces us to inhale sharply and can also be referred to as singultus, which is a Latin term which is translated to mean ‘the act of catching one’s breath while sobbing’2.

The ‘hic’ sound that you hear when you hiccup is caused by diaphragm spasms. When your diaphragm contracts arbitrarily, it causes you to inhale; however, this inhalation is very short due to the rapid closing of a structure called the glottis3The glottis is the space between your vocal cords and it is its closing that causes the ‘hic’ sound.

Why do we hiccup?

It’s not really known exactly why we hiccup but here are some theories4:

  • Some scientists believe that we hiccup due to disruptions of the nervous system that leads to respiratory muscles (the muscles that help us breathe), which may be why some people hiccup when they’re upset, nervous, excited or exposed to different temperatures – this makes sense because we know the nervous system is directly related to all of these things!
  • For those everyday, arbitrary hiccups, it’s believed that overeating, drinking too much or eating/drinking too quickly are the causes. When you eat or drink too much, or too fast, your stomach expands to accommodate. Since your stomach sits below your diaphragm, its expansion will irritate the diaphragm, which will then contract and cause you to inhale.

Either way, your respiratory muscles are essentially acting out, causing you to rapidly inhale. The best way to stop hiccuping is likely to get in control of your breathing pattern, which is why holding your breath seems to work3!

1. Whitelaw, William A. 2007. What causes hiccups. ScientificAmerican.com. <http://www.scientificamerican.com/article.cfm?id=what-causes-hiccups&gt; January 30, 2013.

2. Wilkes, Garry. 2012. Hiccups. http://reference.medscape.com/ <http://emedicine.medscape.com/article/775746-overview&gt; January 30, 2013.

3. Murphy, Glenn. 2007. Why do we get hiccups and how do you stop them. http://www.sciencemuseum.org.uk/ <http://www.sciencemuseum.org.uk/onlinestuff/snot/why_do_we_get_hiccups_and_how_do_you_stop_them.aspx&gt; January 30, 2013.

4. n.p. 2004. Why do we hiccup. http://www.medicalnewstoday.com/ <http://www.medicalnewstoday.com/releases/7623.php&gt; January 30, 2013.


Ever get too nervous to step onto a stage and speak in front of an audience? What about getting anxious about an upcoming test? Whether it’s when you think of the future or performing a simple task like driving, we’ve all felt anxious at one point.

What is anxiety and why do you get anxious?

Anxiety is often confused to be the same as fear, but I think it’s important to distinguish one from the other. Fear is your response to a known threat that’s in your surroundings while anxiety is more of a response to an unknown threat or an internal conflict1. We don’t fear the future because we don’t know what is in store for us, but not knowing what will happen can make us anxious. Even though they are caused by different situations, their modes of action in our body are the same.

Getting anxious is simply the flight-or-fight response to an unknown threat and is meant to be a evolutionary response for survival2. Without anxiety or fear, we would probably be reckless and die at a young age as a result.

How do you get anxious?

Fear and anxiety are both emotions regulated by a part of your brain that’s called the amygdala3.

When you’re in a situation that would normally lead to anxiety, such as having an internal conflict, a system known as the locus coeruleus (which is found in the pons), is signalled by the thalamus to release a hormone. This hormone, norepinephrine (NE), targets the amygdala, in addition to other systems.

This causes the amygdala to target another part of the brain (the hypothalamus), which causes the release of cortisolepinephrine (aka adrenaline) and NE to induce the ‘flight-or-fight’ response4. Some cortisol goes back and targets the amygdala, which intensifies the signalling and, therefore, the symptoms1.

The three hormones and the nervous system will target organs like your eyes, heart, sweat glands and bladder and will signal for the pupils of your eyes to dilate, your heart to beat faster, your sweat glands to release more sweat and for your bladder to relax. This relaxation of your bladder results in the likeliness of urinating if you are really anxious or scared. Hence the saying ‘I almost peed myself’.

The general signalling path that results in anxiety.

The general signalling path that results in anxiety and a few symptoms of anxiety.

1. Steimer, Thierry. 2002. The biology of fear & anxiety-related behaviours. Dialogues in Clinical Neuroscience, Vol, 4, No. 3, pp. 225-249.

2. DeMarco, Anthony J. 2009. The biology of fear and anxiety. MASCCares.com. <http://masccares.com/index.php?option=com_content&view=article&id=6:biologyoffear&gt; 02 January 2013.

3. Feinstein, J.S., Adolphs, R., Damasio, A., and Tranel, D. 2011. The human amygdala and the induction and experience of fear. Current Biology, Vol. 21, No. 1, pp. 34-38.

4. Layton, Julia.  2005. How fear works.  HowStuffWorks.com. <http://science.howstuffworks.com/life/fear.htm&gt;  02 January 2013.