Category Archives: Physiology

What The Hell, Is A Cell?

 

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If your elementary and high school science education was as crappy as mine you were left with a picture of a cell as a featureless white ball. UGH! No! Cells are “space stations bristling with sensory array” something about weapon systems according to Xs excellent description in the Biology of Star Trek. Plus we have magic portals through which chemicals aka chems enter and then Do Stuff! You need a good mental image of cells to protect yourself from BS pseudo-information. Like news “health stories” the bulk of which seek to make you feel bad about what you eat and how you look. They have a patina of science (via medicine! A vastly unscientific thing!) but are so superficial there is no reason to believe what they are claiming is true. Once you have a good pic in your head of what a cell is you will be well on the way to knowing how fake and crappy the information in those kinds of reports is. Because it never has anything to do with actual cells. Or with any other aspect of how the body actually works.

Cells are like little creatures. There are one celled creatures. Cells were the first alive things that ever existed. The key is the membrane. It’s not a skin. Skins, even grape skins are made of cells. Then what the hell is a cell made of? Goo. Inside. Of the membrane! It’s two layers of oil (lipids in biotalk) with a layer of water in between. Hey! Oil and water don’t mix! True. They aren’t mixed! They are holding each other in a kind of crazy chemical bonds-level dynamic tension. Like the planets in the solar system. The sun’s gravity holds all the planets where they are. Which is determined by how much mass each has. So the water molecules love each other and grab on. And the lipid molecules do the same, making two layers. More lipids make a third layer and it rolls up into a closed sphere! That’s actually really lumpy. How’s it rollup? I don’t know. It’s one of those molecules clutching onto each other’ shape of making things. (Chemistry is not about the periodic table. It’s about lumps.)

The membrane is like Jell-O salad (which is gross). Picture It as transparent with bits embedded in it. Except on the cell some stick out. They are receptors, three-dimensional molecules, globs that receive chems that come, via the bloodstream or out of nerve endings, to the cell. Why do they come? To tell the cell to do something. Secrete a hormone, that then comes out through the cell membrane, goes to another cell and tells it to do something. I know. It sounds pointless. And endless. It’s not. It has ends. But lots of stuff on the news and in actual medicine including drugs, act on cells and their chems. This is dead easy to understand and yet never taught in school. Bizarre!

Two ends: 1) sometimes the chem coming into the cell is glucose a.k.a. fuel. All cells eat glucose. Except neurons who eat lactate. Ick! I always imagined it as runny cream of wheat . And they only eat that. And other cells only eat glucose. But glucose is sugar and sugar is bad for us! No. Sugar is good for us. Sugar is food. Yes, the Anti-Food Crazies say sugar is evil. But they are very confused about biology. We’ll deal with them in another post. So everything we eat is turned into glucose or proteins. Or fats (lipids is the correct term) which are just waiting to be turned into glucose. And burned as fuel in the cells. That, recall, are little creatures. So how does the glucose get in the cell? Through the magic portal! What’s so magic about it? Insulin. Why? Insulin is a chem that goes through our bloodstream and attaches to a cell’s receptors for insulin. Always called the insulin receptor. But the cell is coated in them. Like sprinkles on a doughnut. The insulin hits the receptor and the receptor goes: Oh! Glucose is here! And opens a port in the cell membrane (Jell-O salad) and the glucose comes in. How’s it open a port? That’s where the Jell-O salad comes in. See one of those hunks in the Jell-O salad? Let’s call that the molecule. When the insulin docks with insulin receptor the cell sends a message to that molecule and a bit of phosphorus is added to it. When a molecule has another hunk of molecule added to it or a hunk snipped off, the new molecule refolds. It makes itself into a new shape. (I’ll have a post on this at some point. If anyone knows of animation showing refolding let me know!)  So when the phosphorus is added to the molecule inside the cell membrane it refolds into a shape that is long and skinny and flat. And that then opens up and is the portal that the glucose comes in through. it’s a little hard to picture I know. That’s because we’ve never been taught how to picture molecules changing shape. And going flat and having a hole through them. :^/ Nope. We were shown the stupid periodic table.So, then in the cytoplasm (goo) some chemical process takes the glucose to the mitochondria. The mitochondria are too trippy for words. They used to be: a free living creature! A little other animal that a bazillion years ago one celled creatures grabbed up and integrated into their biology! If that’s not the most sci-fi thing in the world I don’t know what is! Mitochondria produce energy for the cell. “Energy” in biology and also in physics is a squishy intellectually problematic concept. I apologize for having to use it here. But hey, it’s not my fault it sucks so bad! Anyway the glucose fuel goes into the mitochondria (which have their own wee ring of DNA because they used to be a creature!!!) And the mitochondria does some chemical thing with the glucose that we call energy and that our cells need in order to be alive.

2) Another end that the chems traveling around us make happen is when under a neurotransmitter contacts a muscle cell and makes the muscle cell contract. Contracting is getting shorter. Muscle cells are arranged so that one thing, that’s all they can do, allows all the different sorts of movement we can do. Do an air arpeggio with your fingers. All the muscle cells are shortening and extending ie ‘uncontracting’. That’s all they’re doing when you do that. It’s how they are arranged that allows that. And that they are little tiny things like pixels. Trippy. I’ll try and get more info on that for another post.

So lots of chem messengers go to lots of cells and tell them to do something, to NOM NOM on glucose, for muscle cells to shorten. Or any of the other ‘ends’. Like a cell type in the kidney releases a chemical that acts on another cell type right next-door in the kidney to make it hold onto more sodium (or less) versus sending it out of the body in pee.

Cells and chems. Cells and chems. Think about that every morning when you get up. And in three months you will be so damn used to it that when you see or read about some cells and chems I didn’t even talk about you’ll go “I can totally picture that”.

And when the news has stories about your “health” and there are no cells or chems in that story you’ll go WTF?!

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