The Speed of the Small

• Neural Impulses
• From .1-100 m/s
• Muscle position nerves--119 m/s
• Pain--0.62 m/s
• Touch--76.2 m/s
• Thought--25 m/s
• Speeds are affected by...
• Temperature
• Warm blooded animals are faster
• Pathway width (axon size)
• Wider is better
• Giant squids living in the arctic have huge pathways (axons) to make up for the cold temperature and having no insulation (myelin sheathing).
• Insulation (myelin sheathing)
• Vertebrates have insulated nerves and therefore way faster impulses
• Quite a difference is made--1 m/s  (inverts) vs 100 m/s (verts)

• Muscle Twitching
• Fastest: Eye twitching at 7.5 msecs (milliseconds or 1/1000th of a second)
• Calf muscle--100 msecs

• Reflexes
• Fastest: vestibulo-ocular reflex (The rotation of your eyes correcting for head tilt.  You can witness this by looking in the mirror and cocking your head to the side and noticing how your eyes maintain vertical position.).  There are only three neurons in the whole system and the whole process takes 1/100th of a second to correct.

• Sight
• We can notice moving image frames slower than 1/16th of a second.
• Most movies are 24 to 48 frames per second

• Cell division
• Some bacteria can divide as quickly as once every 9.8 minutes

• DNA Translation
• The RNA polymerase can add 50 base pairs per second

• Hearing
• The timing difference between sounds reaching ears is known as the interaural time difference.  It's important in determining which direction a sound comes from.
• This difference is maximally 660 microseconds (660 millionths of a second) when the sound is at a right angle to the front of the face.

Pictures from here, here, here, here, here, here, and here.

Works sighted [sic]:

http://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter10/medialib/CH10/html/ch10_5_1.html
http://www.biologymad.com/NervousSystem/nerveimpulses.htm
http://www.funtrivia.com/askft/Question82039.html
http://en.wikipedia.org/wiki/Vestibulo-ocular_reflex#Speed
http://news.softpedia.com/news/The-Fastest-Muscles-83834.shtml
http://en.wikipedia.org/wiki/Persistence_of_vision
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2064748/
http://en.wikipedia.org/wiki/Interaural_time_difference
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC279347/?tool=pmcentrez
http://www.dnareplication.info/speedofdnareplication.php

Gyroscopic Eyes - Vestibulo-ocular Reflex

If you're anything like me, learning this will only reinforce how little you actually know about the adaptations your body has that you constantly use thoughtlessly.  O, the wealth that you don't/can't even comprehend!!!

Please do this:

• Go to a mirror.
• Stare straight ahead.
• Find a marking/discoloration on your iris or some distinguishing vein that you can watch during this process.
• Rotate your head to the left and then the right taking notice of the compensatory motions of your eyes.

What do you see?

• Now try it fast.
• Slower.
• See how far your eyes will rotate.

Think about it.  Your eye gyroscopes all the time and you've probably never really thought about how (or, at least, I didn't).

THAT'S AMAZING!!!

Here's the gist of what I understand to be happening.  Your inner ear is composed of channels filled with liquid that as we move cause slight currents to be detected by the minute hairs within the vestibule.

That information then follows the below path:

It then tells muscles wrapped around the eye to rotate the eye:

Notice the way the muscles wrap around the eye making it possible to rotate the eye.

The exceptions to this rule are worthy of note.   Ever felt like the room was spinning?  Maybe that's because your eyes were!!  When you drink, spin yourself, or put cold/warm water in your ear the brain receives some confusing signals that end up causing the vestibulo-ocular reflex to get a little wonky (called nystagmus).  Your eyes rotate when they shouldn't!!  Also, when a doctor is trying to to assess the severity of a brain injury and possibly determine if the patient is brain dead, rotating the head to see if the eyes rotate involuntarily is one method.  

Not even going to pretend I didn't steal this from Wikipedia:

"Using these direct connections, eye movements lag the head movements by less than 10 ms, and thus the vestibulo-ocular reflex is one of the fastest reflexes in the human body." http://en.wikipedia.org/wiki/Vestibulo-ocular_reflex

AWESOME!!!!