If you’ve been following along lately, you know that I basically have negative free time. If you haven’t been following along lately, well, now you know that I basically have negative free time. That’s what taking a more-than-full-time course load + work + the rest of life means. Fact of life. I really enjoy school (because I’m a nerd), but I haven’t been particularly excited about it taking over my entire life and leaving me with next to no time for, among other things, creativity (nerd alert, again). So I decided to combine the two. Welcome to my hybrid art journal/homework notes notebook.
Turns out I’ve been “art journaling” since middle school. I just didn’t know there was an actual term for hybrid notebooks full of handwriting + journaling, sketching + drawing + painting, and collages. The more you know, yeah? (Yeah. Get ready to know more, because this post doubles as a neuroscience lesson…)
On the first page (above) I used washi tape from a past Studio Calico kit to affix a gorgeous rendition of the brain to the page. The brain, which I printed on vellum, is part of artist Angela Willetts‘s “Inhabited” collection. It’s really amazing.
Pages 2 and 3, the first full bleed spread, hold a detailed print-out of the nervous system (for reference) and the phrase “the nervous system” in kraft alpha letters. I left the two “sets” of pages after these blank, and when I have more time I plan to fill the four pages that follow these with details about the central nervous system and the peripheral nervous system, and its four subdivisions.
For now, though, I moved onto the section of the notebook documenting neurons. The title pages for this section are shown above. I splattered black paint on a kraft tag, which I then affixed to the page with washi tap, and the right side page. I used hot pink glitter alpha stickers to spell out “neurons” on the kraft tag, then wrote “the foundation of the nervous system” below the stickers. I really love the look of the splattered paint. It’s not really representative of neurons, but it kind of is and I really think that it just works.
Next I included a hand-drawn sketch of a neuron. Its basic anatomical features are labeled. The page across from this sketch hold two blocks. The top block holds notes about the different structural features of neurons (unipolar v. bipolar v. multipolar), while the bottom box holds notes about the different functional features of neurons (sensory/efferent neurons, motor/afferent neurons, and interneurons).
Ah, the Action Potential. A process that I spent years thinking was incredibly difficult and incomprehensible until something this semester just clicked. I won’t bore you with the details, but the analogy using the iPod (representative of a neuron) to describe the process of an Action Potential is what did it for me.
Okayfine, I’ll bore you with the details. But only because I think this analogy is REALLY COOL. If you’re interested, read the two paragraphs below. If not, skip to the next photo.
Action Potentials are necessary in order for neurons to communicate with each other. The Action Potential begins in a neuron’s dendrite, travels along the cell’s axon into the axon terminal, and passes to the receiving neuron. It’s an incredibly quick processes, whereby the electrical charge of the neuron’s membrane changes in order to allow for the transmission of an electrical impulse along its membrane.
Think of it like this: the body of the iPod – the rectangular portion – is like the soma of the neuron. It is where the ‘brains’ of the system are encased. In this case, the body of the iPod is also representative of the dendrites of a neuron, as it is the portion of the device that receives input. Specifically, the round button on the bottom half of the device (because this is an early generation iPod, duh) is where input is received. In order to select a song, the round button must be pressed hard enough to generate an electrical signal within the device. That is, a predetermined and constant threshold must be exceeded; in this case, it is caused by pressure from your thumb or finger.
Once the threshold has been reached, an electrical signal is generated. In the case of the iPod, the signal travels from the device itself (soma), along the plastic-coated (myelin sheath) earbuds cord (the axon) and into the earbuds (terminal buttons within the axon terminal). The selected song then “synapses” from the earbuds into your auditory system. Badass analogy, amirite?!
The next spread breaks the Action Potential down a bit. Phases 1 and 2 are documented here: depolarization and repolarization. Again, these are concepts that I was really struggling with “getting” until I wracked my brain for a good analogy, and had an “AH HA!” moment. Just because I’m really proud of my analogy, I’m sharing it below. Again, read it if you want. Or skip it if you don’t.
In order for an Action Potential to occur, a few things must happen:
- A stimulus must be strong enough to surpass the threshold level (-55 mV)
- Voltage-gated Na+ channels that sit along the neuron’s membrane must open
- Extracellular Na+ ions must rush into the axon via the open voltage-gated Na+ channels along the membrane
The occurrence of these factors happen in rapid succession as part of a domino effect: as soon as a stimulus strong enough to surpass the threshold has been generated, the voltage-gated Na+ channels lining the axonal membrane respond to the change in voltage by opening. Once open, the extracellular Na+ ions rush through, flooding into the axon. Remember that the interior of the axon was more negative before positively charged Na+ ions rushed in. Once the positively charged Na+ ions rush in, the intracellular state of the neuron becomes less negative, or more positive. The intracellular voltage increases sharply and exponentially (known as ‘overshooting’). This process is known as depolarization, or the process of reducing the neuron’s polarization (the state of polarity mentioned in the beginning), and can be easily visualized by imagining shoppers on Black Friday.
Imagine sitting outside of Target in the middle of the night on Thanksgiving (Black Friday Eve). Outside of the store is the big crowd that you’re a part of (Na+), waiting for the doors (voltage-gated Na+ channels) to be unlocked so that you can all rush in a try to score the best deal possible on any given product. Inside of the store there are, by comparison to the crowd outside, only a few employees on hand (K+). This dichotomy of less workers inside the store/more shoppers outside the store represents the difference between the less positive charge of the inside of the neuron and the more positive charge of the outside of it.
When the clock hits a predetermined time – the threshold – an employee unlocks the doors and the big crowd of people rush into the store. This is representative of the cell’s threshold being reach and the resulting rushing in of Na+ ions in response to the voltage-gated Na+ channels being unlocked, which itself is a response to the exceeding of the threshold.
Well. That’s it this time around. I’m kind of jumping into this “Get Messy” thing as a very casual, infrequent participant. Not because I don’t want to participate/contribute regularly, but because I don’t want to commit to doing so when I know I can’t uphold that promise. So. Whenever I have some new pages of notes ready to share – and the time to photograph them and write a post about them – I will. I PROMISE.
And who knows? Y’all might just learn something else new next time!