day 29- in this past month, what have you learned

I am a nerd. But bare with me. (or feel free to ignore this post all together). This is an ear. This month in school I learned EXACTLY how hearing works. It just fascinates me. SO... you get to learn.

Above you see the outer ear. The sound goes into the pinna (outer ear), through the ear canal and moves the tympanic membrane (AKA ear drum). On the other side of the eardrum are 3 ossicles (tiny ear bones) in an air filled cavity. Ok, so most people can probably tell you about hearing up to this point. Here's where it gets exciting!

The final ossicle is called the stapes. Its footplate lines up to the oval window. On the other side of the oval window is a liquid filled spiral called the cochlea. The vibrations of the ossicles cause the stapes to send waves into the cochlea. Those waves activate hair cells along the cochlea depending on the frequency. You can see  on the above diagram that High frequencies activate near the base and low frequencies near the tip.

And the excitement continues!

In the cochlea there are LOTS and lots of hair cells. 3 rows of outer hair cells, and one row of inner hair cells. As the different parts of the cochlea are stimulated by different frequencies it causes the Outer hair cells to move, the movement opens up small ion channels and a positive potassium ion rushes into the negatively charged cell. In order to kick the potassium out, the cell begins to 'dance'.

This upper most outer hair cells are connected to the tectorial membrane. The dancing of the outer hair cells causes the liquid inside the organ of corti. This causes the ion channels in the inner hair cell to open, admitting potassium and when the electrical build up reaches threshold, neurotransmitters are released and sent to the brain via the cochlear nerve.

Tell me that's not amazing! It is happening every second of every day. Without our even knowing it, or controlling it.

Who said the body isn't amazing? And next time you get angry with your body for revolting against you (which happens) Think about all it's doing right!