More Body Oddities

By Dr. Stephen Juan

WHY DO MY EYES HURT WHEN I’M TIRED?

We rarely think of the eyes as containing muscles, but that is what is involved in tired eyes.  Our eyes contain muscles.  Like other muscles in the body, eye muscles get tired when they have to work too much.  Each eye has six extraocular muscles attached to the outside of the eyeball which turn the eyes in all directions.  The extraocular muscles must coordinate their movements so that both eyes look in the same direction at the same time.  The sphincter and dilatory muscles open or close the pupils thus defining how much light is allowed into the eye.  The ciliary muscles attach to the lens inside the eye.  When these muscles contract or relax, they change the shape of the lens thus altering its focus.

Reading and other close work involving the eye provide a workout for these muscles.  They get tired and we feel it.  In addition, much of the tired eyes we experience that is attributed to eye strain may be caused by eye dryness.  Our eyes need tears to operate efficiently.  We spread tears across our eyes when we blink.  We need to blink often.  It has been found that when we are engaged in close work we slow down the rate at which we blink.  As a consequence, tears are less likely to spread across the eyes and we experience pain from tired eyes.

WHY MUST I PUT A THERMOMETER UNDER MY TONGUE TO TAKE MY TEMPERATURE?

There are five methods of taking a temperature:  Under the tongue, in the ear, against the armpit, against the inner thigh, and in the rectum.  Accuracy, speed, and comfort are the three considerations in this.  Under the tongue gives a more accurate temperature when the oral temperature method is used.  The rectum gives an accurate reading too but is awkward to administer.  The other three give less accurate readings.  Under the tongue has an advantage in accuracy since under the tongue insulates the area from outside influence such as food, drink, and air that could bring the temperature up or down.  Under the tongue has an advantage in speed since the soft tissues and blood vessels of the tongue are ideal resting spots for a thermometer and thus a second reading is rarely necessary.  Under the tongue has an advantage in comfort since keeping the thermometer above the tongue is actually less comfortable with the thermometer bouncing around the inside of the mouth. 

WHY DO WE WAKE UP WITH BAD BREATH?

Bacteria build in the mouth overnight and are less likely to be washed away by normal daytime swallowing and drinking.  Bacteria give off the foul-smelling compounds which attach to our gums, tongue, and teeth.  Dentists call this bad breath in the morning “fetid breath”.  Contributions to the bacteria come from food left overnight in the mouth, plaque, saliva in spaces between the teeth, on the gums, and on the tongue, and dead tissue that is being constantly shed by the mouth, gums, and tongue.  Microorganisms convert this “food” into amino acids and peptides which in turn break down into compounds with a pungent sulfur odor.  The best defense against fetid breath is regular salivary flow such as when you are talking, chewing, and swallowing.  You do less of these activities at night while asleep.  Brushing teeth also helps, flossing too, and general good oral hygiene is critical.  Rinsing or drinking something eliminates fetid breath because liquid of any kind functions like saliva.   

HOW DO FIGURE SKATERS KEEP FROM GETTING DIZZY WHILE SPINNING SO FAST?          

It is about “blurred constant”.  They do the opposite to what ballet dancers do!   The pupils of the eyes of an untrained skater gyrate back and forth during a spin.  The rapid pupil movement is caused by the eyes catching objects within view or attempting to focus on a fixed point.  The eyes simply cannot keep pace during a spin or hold to the fixed point.  The spinning is too fast.  This causes dizziness.  For an untrained skater the dizziness does not occur in the middle of the spin but when the spin stops.  It is very similar to what is experienced when one alights from an amusement park ride and “cannot find your feet”.  On the other hand, a trained skater learns how to keep the pupils from gyrating.  The trained skater does not try to catch all objects within view or focus on a fixed point during a spin.  Instead, the pupils of the eyes remain in a stabilized position only lightly focusing on the space between the skater and the next closest object.  This gaze is has been described as being very much like a daydream.  The technique that skaters learn to keep the eyes lightly focused is called “blurred constant”.  It is an imaginary line running around the ice rink.  The imaginary line may be in the seats or along the barrier of the rink.  During a layback spin when the face remains looking upward, the imaginary line might be on the ceiling.  The important consideration is that the skater feels balanced and centered.  Even when the hands and legs are moving about rapidly, the skater feels that their head, shoulders, hips, and legs are under control.  Dancers do not spin as fast as ice skaters.  Dancers can use a technique called “spotting” and avoid dizziness.  Spotting involves focusing on a particular object in the visual field.  Any object will do as long as it does not move.  When using spotting, dancers turn their head at the very last moment in the spin and again focus on the spotted object.  The rest of the body follows.  Skaters do not turn their head but keep the body aligned at all times.  Skaters cannot use spotting because their spins are much faster than those of a dancer.  Some skaters achieve six complete rotations every second.  You can spin faster on ice than you can on land just as you can skate faster on ice than you can run on land.      

News Archives: 2010 April 2010: Little Known Facts about the Brain March 2010: Religion and Health February 2010: Sunny Surprises January 2010: Does the Full Moon Change Our Behaviour? 2009 December 2009: What Lies About November 2009: Kindness Guerillas - Join the Fight! October 2009: Altruism Can Rule the Day September 2009: Our Lost Idyllic Childhood? August 2009: The Unknown Trauma of Child Abduction July 2009: Gekkomania Alive and Well June 2009: Why do we dance? May 2009: Exposing Sun Risks April 2009: Building Self-Esteem in Hard Times March 2009: Death by Anesthesia - Malignant Hyperthermia February: Why do we have no heroes today? January: Stress on young doctors 2008 December: Syllogomania September: How body language can work for you August: The blues busters July: 'Mother-to-be' fantasies are pregnant with meaning June: How kids cope with tragedies May: Things that Mums say: are they true? April: Future Items March: More body miscellany February: Where there's smoke... January: Is the Yeti now extinct? 2007 December: Odd Body Miscellany November: Teenage risk-taking behaviour October: Peyronie's Disease September: The Othello syndrome August: The new wrap on swaddling July: Where did the belief in guardian angels come from? June: What is real success? May: Is a time machine possible? April: What to say to someone who's dying March: More odds and ends behaviour February: Tiny machines will change us forever January: Do you have to be manic depressive to be creative? 2006 December: Sick Sperm November: Odd Statistics 1 August: Is it more natural for children to be cruel or kind? July: Satanic Cults Won't Go Away April: Something to Panic About March: Step This Way for an Argument February: Who's Afraid of Intimacy? January: Endangered Speciesism?