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Fizzix in Our Bodies pt. 1


lindsh23

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Since I spend so much time at New Visions and my future studies will most likely focus on the medical aspect of science, I have decided to see if I can create some blog posts focusing on the physics that goes on... in our very own bodies! Please excuse my nerdy anatomy obsession

This post will focus on the physics behind our nervous system!

Our nervous systems, both central and peripheral, focus on the idea of neurotransmission. Our nervous system relays messages from our body to our brain and back again using electrical impulses; this process is known as neurotransmission. Nerves near the surfaces of our bodies pick up stimuli from the environment, such as heat, light, and sound, via receptors. These stimuli cause the chain reaction of neurotransmission to occur. Here is a diagram of a typical neuron, or nerve cell:

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So what happens after a neuron senses a stimulus? Well, first, let's look at how neurotransmission is performed. At rest, the axon, or the shaft looking thingie, of the neuron is polarized. The outside of the axon contains positive sodium ions, and the inside contains positive potassium ions and negative chloride ions (I know, this seems like chemistry... but chemistry is basically the physics of electrons, so stay with me!). The fluid on the inside is negatively charged, giving it a negative potential of -50 mV. At rest, sodium ions cannot penetrate the axon barrier.

A small electrical change caused by a stimuli causes the resting potential to become less negative, and once it breaks a threshold, it becomes permeable to the sodium ions, causing an action potential, where the axon fluid depolarizes. During this depolarization, sodium ions move down a concentration gradient, transmitting an electrical impulse across the neuron to the next neuron, triggering this action potential from neuron to neuron.

While a neuron repolarizes (its way of regrouping), it goes through a refractory period, which is the delay between when it can fire its next impulse. This refractory delay prevents nervous system overload (what I picture as some sort of spontaneous nervous combustion!).

blogentry-1411-0-75711300-1414984116_thu

The speed of neurotransmission is affected by the diameter of the axon (larger diameter=faster transmission time... more area for 'flow') and also by the amount of myelin sheath, or the insulation of the axon of the neuron. The deterioration of myelin is what causes multiple sclerosis, which is why those affected by MS suffer from the deterioration of their nervous function.

Well, fizzix friends, I hope I have not bored you too much with my nervous system lecture. More to come on the physics of our bodies!

Until next time, Fizzix Community, until next time.

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