Tracing a Sneeze

Where does a sneeze start? It all starts with a foreign particle that enters and irritates the nasal mucosal lining. This can include dust, pollen, bacteria and even pepper. Your body’s reaction to this foreign particle is a sneeze. The respiratory, nervous and muscular system all work together to expel foreign particles out of your nose. So now a simple sneeze is not so simple. The following steps are the basics of a sneeze that will be further explained throughout the blog:

Respiratory System

  1. Starting with the respiratory system, a sneeze starts when a person breathes in a foreign particle. (Most people breathe through their nose to help trap these particles and bacteria).

  2. The nose is lined with hair like projections called “cilia” to help trap bacteria and dust particles. Cilia protect bacteria from further traveling down the respiratory system into the lungs. If many cold viruses and other particles do manage to travel down into the lungs, pneumonia can develop and cause other respiratory problems.

  3. Other shelf-life projections in the nose called turbinates trap and collect foreign particles. Turbinates are bony projections inside the breathing passage on each side of your nose.

    1. People have three turbinates on each side: inferior, middle, and superior.

    2. The inferior turbinate is the largest of the three; the superior turbinate is the smallest.

    3. Turbinates main function is to prepare the air being breathed in. This includes filtering and trapping foreign particles, warming cold air, and humidifying air to prevent the drying of the bronchial tubes.

    4. A nasal mucosal lining lines the turbinates and this is where particles get trapped. This then triggers a reflex arc.

     

Nervous System (see physics of sneezing for more detail)

  1. Nerves in the nasal mucosal lining act as the receptor and eyes, nose, lungs, diaphragm and chest muscles act as the effector.

  2. Afferent nerves in the nasal passage carry signals to the “sneeze center” to trigger a reaction. The sneeze center is also known as the medulla which is located in the hindbrain. The medulla also controls reflexes such as breathing, vomiting, and digesting. The Trigeminal Nerve is responsible for this.

  3. Efferent nerves or motor nerves signal the muscles in the eyes, nose, and chest to contract.

Muscular System/Respiratory System

  1. The muscles involved in a sneeze include the eye, abdominal, and chest muscles. The diaphragm and vocal cords are also involved.

  2. The muscles in your eyes contract causing eyes to shut automatically.

  3. The diaphragm and abdominal muscles work together to force air out of the lungs, nose and mouth at a speed of 100 mph.

  4. The diaphragm moves down, lowering pressure in the chest cavity. The lowered pressure causes air to be pulled in to fill the lungs to equalize pressure. Abdominal muscles also aid in breathing.

  5. Abdominal muscles such as the intercostals, contract increasing space in the chest.

  6. As air is filled in the lungs, the abdominal and intercostals contract again forcing air back out at a high speed.

     7. The air forces mucus and irritant particles out of the nose.

So Where do these particles end up now? Well, hopefully it won’t be on a fellow classmate, colleague, or neighbor. Mucus is a perfect growing medium for many kinds of bacteria, such as Streptococcus pneumoniae that can cause sinusitis. So please cover up when you cough and sneeze!

-The Sneezeweeze team

Here is a simple and short video on how sneezing occurs.

References:

All images taken from gooogle images

Nasal anatomy – the turbinates. (2005, April 21). Retrieved from http://www.obstructednose.com /nasal_anatomy_turbinates.html

Squires, S. (2006). Anatomy of a sneeze. Retrieved from http://www.washingtonpost.com/wp-srv/health/interactives /cold/

What is a sneeze. (2009). Retrieved from http://www.weirdfacts.com/facts/3253-sneeze-facts.html

Wilson, T. (2012). The science of sneezing. Retrieved from http://dsc.discovery.com/tv/time-warp/articles/sneezing.html

http://www.umm.edu/patiented/articles/what_causes_sinusitis_000062_2.htm

Eyes, Please don’t leave me~!

When you sneeze, the spray of mucus and saliva can reach a speed of 100 mph.  So some people have come to believe that it is impossible to sneeze with your eyes open because they will pop out or bulge out of your head.  This is actually not true.  The eye has muscles including the medial and lateral rectus, superior and inferior oblique, and superior and inferior rectus to keep the eye in place.  The optic nerve and the conjunctiva, the covering of your eye that is a squamous epithelium layer also plays a role in making sure your eyes don’t leave its sockets.  These structures keep the eye from falling out when you sneeze.  So then why do our eyes close when we sneeze? Well, there is no actual answer.  It’s just an involuntary reaction that your eyelid muscles contract when you sneeze causing them to close.

If you don’t believe me, here is a video of Adam from the show Mythbusters sneezing with his eyes open.

References:

http://health.howstuffworks.com/human-body/systems/eye/sneeze-with-eyes-open.htm

http://www.medicinenet.com/script/main/art.asp?articlekey=52283

http://www.tedmontgomery.com/the_eye/eom.html

Sneezing is a protective reflex

Sneezing is a reflexive act that happens when your nasal passageways are irritated by something. Sneezing involves a reflex arc, which is the circuit traveled by impulses producing a reflex action – from the receptor organ, through the afferent nerve (sensory nerve), nerve center, efferent nerve (motor nerve), to the effector (another organ, hormone, etc.). Here are the steps:

1. An irritant is detected by nerve endings (receptors) in your nasal passageways; this irritant could be anything from a smell, dust, viruses that attack mucosa membranes, and so on.

2. Nerves carry these impulses to sneezing center in your brain stem.

3. Then the sneezing center sends the instructions down your facial nerves and nerves that lead to your lungs and diaphragm.

4. This causes your eyes to start to water and your nasal passageways to secrete fluid. This also causes you to take in a deep breath, caused by an abrupt movement of your diaphragm.

5. Next, the diaphragm and your chest muscles contract, which causes the air to leave your nose and mouth suddenly and fast.

References:

http://medical-dictionary.thefreedictionary.com/reflex+arc

http://entertainment.howstuffworks.com/arts/circus-arts/human-blockhead2.htm

http://www.washingtonpost.com/wp-srv/health/interactives/cold/

Achoo!

People sneeze all the time, but they don’t really know how sneezing works (including myself). Our goal of doing this post and future posts is to inform readers how sneezing works in details – not just your nose getting a tickle, but how and why. Sneezing is a natural body mechanism to get rid of particles in your nose that can cause irritation. In some other cases, sneezes can be due to a cold and psychosomatic reactions (internal reactions of mind, emotions, stress, conflicts, thoughts etc). Sneezing while a person has a cold sends out about 40,000 infectious droplets that can spread the disease. Also, sneezing, called sternutation, removes the air from your lungs at speeds up to 100 mph. So a person who sneezes incorrectly can get seriously injured. One of the behaviors a person shouldn’t do is stopping a sneeze that is in the process. This can cause hearing loss and damage in blood vessels in your head. There are also some useful techniques to stop sneezing when appropriate. We will talk more about how all these come in depth.

Here is a fun video of people sneezing in slow motion. Enjoy!

References:

http://www.wikihow.com/Stop-a-Sneeze