There’s public radio telethon week, toll roads, vending machines that give you Diet Pepsi when you clearly pushed the “Coke” button, and near the top of the list are hiccups. These are a few of my least favorite things. Oh, you know this guy loves the human body. There are few marvels in this world more elegant, more profoundly complex than the body and it’s nuts and bolts, but son of a [CENSORED], hiccups are the devil! I seriously doubt that a successful pick up line has ever been delivered while battling with the hiccups. Hiccups lie in wait like mean-spirited hecklers waiting to kill the mood of your acceptance speech or interrupt the punch line of your best dirty joke. So in this episode of Forgotten physiology we’ll pose the question; Hiccups, what’s your deal?
Synchronous Diaphragmatic Flutter (or Miss Jackson if you’re nasty)
Mechanically speaking, hiccups are nothing more than spasms of the diaphragm; short, involuntary contractions forcing air through the windpipe that is then immediately closed off by the tough, elastic flap of the epiglottis. This closes off the vocal chords like a trap door that says “No more air for you! No!” and produces that signature, sexy frog sound of a classic hiccup.
You have a left and right phrenic nerve that connect to the diaphragm to control its contractions and receive sensory input in return. “Sensory input?” Well sure, you don’t just blindly send out messages. You look for a response. Your nervous system is all touchy feely and needs to be able to sense where everything is…no organ left behind. Those nerves are the only electrical wiring operating the movement of the diaphragm. So any significant disruption or irritation of the phrenic nerves can cause spasms and ultimately hiccups. For example, if you just had a bad breakup and decided to go Tazmanian Devil on 2 large orders of pork fried rice from Wong’s Wok, a full or distended stomach can press on the phrenic nerves and trigger hiccups.
But who is really in control?
We may not think about it but the diaphragm is made of “skeletal” muscle. If you remember our chat from muscle mania, skeletal muscle is under the control of the somatic nervous system. This typically means that it is under our control. We can, for example, contract our diaphragm muscles ourselves and draw in a deep breath. However, we don’t exactly tell our diaphragms to spasm do we? Ahh…here’s where it gets interesting.
A thought experiment..
You and your body are one and the same right? I mean you don’t feel separate from your body do you? If I ask you to pass the mashed potatoes you don’t ask your hand to grab the bowl. Your brain and your hand flow together, without interruption.
Now think about a hiccup. Does that ever feel like something YOU did? No way, the hiccups happen as reflex and your brain gets the feedback. These are controlled by a “reflex arc,” neural pathways (composed networks of neuron cells) that connect to the spinal chord BEFORE reaching the brain. Some neural pathways have a long way to go to reach the brain, your central command center. The spinal chord works like an intermediary traffic control center, managing the local stuff and all the sensory input from the extremities. This allows motor reflexes to occur instantaneously without checking in at the office (brain) first. Your brain isn’t left out of the loop. The motor neurons of the spinal chord are simply the first to respond.
But why me? Why?!!!
Typically when we get the hiccups we were eating too much or eating too fast, drinking too fast, or hitting the sauce a little heavy (either alcohol or carbonated beverages). Episodes can also be brought on by excitement. I’ve always said that too much happiness is dangerous. These hiccups don’t last long and typically resolve on their own without tongue pulling or drinking water upside down.
There are of course persistent hiccups that are linked to an encyclopedia worth of clinical problems ranging from stress to heart issues to neurologic and metabolic disorders. So if 48 hours have gone by and you’ve still got the chirps then it’s probably a good time to see your doctor my friend.
Stay curious, stay classy, and never stop learning my friends 🙂