Note (12/2015): Hi there! I'm taking some time off here to focus on other projects for a bit. As of October 2016, those other projects include a science book series for kids titled Things That Make You Go Yuck! -- available at Barnes and Noble, Amazon and (hopefully) a bookstore near you!

Co-author Jenn Dlugos and I are also doing some extremely ridiculous things over at Drinkstorm Studios, including our award-winning webseries, Magicland.

There are also a full 100 posts right here in the archives, and feel free to drop me a line at with comments, suggestions or wacky cold fusion ideas. Cheers!

· Categories: Biology
What I’ve Learned:

Quiescence: how much less growth could there be? None. None less growth.
Quiescence: how much less growth could there be? None. None less growth.

Isaac Newton said a body at rest tends to stay at rest. That’s the First Law of Motion.

My mother said a body at rest had better tend to get his lazy teenage ass off the couch and mow the lawn before his father gets home, if he knows what’s good for him. I’m not sure that’s a “law” of anything, but it always got me moving. Eventually.

Inside your body are trillions of cells, and right now many of those are also at rest, in a state known as quiescence. What they tend to do next depends on what sort of cells they are, and how they got into that state to begin with.

Like teenagers, most cells go through phases. But instead of “goth skateboarder” or “sparkly vampire”, your cells go through phases of the cell cycle. The cell cycle is a set of steps cells go through to divide, because reproducing requires very careful planning.

If a cell went through the division process without a roadmap, anything could happen. It could split before it’s ready, and produce deflated Whoopie cushion cells that aren’t helping anyone. It could get its DNA scrambled, and serve it to the daughter cells, family-style. Or it could divide into fourteen cells at once, none quite the way they should be. Like Duggars. It’s terrifying. Thank goodness for the cell cycle.

But a cell’s life isn’t all spent thinking about reproducing. This isn’t college. Sometimes, cells need to exit the rat race of dividing over and over, and rest in quiescence. Take heart muscle cells, for instance. Once your heart has grown to full size during development, you don’t want it getting any larger.

(I know people like to think they have a “big heart”. But if it were big enough to squish your lungs between your ribs, you might reconsider that goal.)

To keep your heart from growing three sizes each day, the mature muscle cells are pulled out of the cell cycle right after a division, in a phase called G1. The “G” stands for “growth”, which is what cells typically do after dividing, but quiescence is a resting state, sometimes called phase G0. Because there’s no growth. Or dividing. Or anything else. The cells just sit there, doing their thing. Pumping blood, keeping you alive and leaving all the worrying about reproducing to you. If you’re into that kind of thing.

This also happens with neurons and other cells that stop growing after development; they enter quiescence, and basically never come out. But other cells can slip into the G0 phase from G1, for just a little post-division breather. Think of it as microscopic maternity leave.

Except that once cells divide, there’s no “parent” cell left. So really, it’s the children who were just produced that get a rest. Lazy kids. That grass is never getting mowed.

These “paused” cells — and in theory, any cells — can be pulled out of quiescence under the right set of circumstances. That could be a growth factor released in the body, or some other growth-goosing signal. Or maybe there are little mothers running through our bloodstreams, telling cells to get busy and do their chores.

The textbooks are silent on that last one. But sometimes, it’s the only thing that works. You do not want to be in the quiescence phase when your father gets home.

Image sources: University of Texas (cell cycle circle), Unilad (lazy, lazy teen), Mom This Mom That (Grinchy heart growth), Life as a Divorced Dad (quiescent kid, uncut grass)

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· Categories: Biology
What I’ve Learned:

Adaptive immunity (at Chuck E. Disease's)
“Don’t make the dendritic cell angry. You wouldn’t like her when she’s angry.”

There’s a lot going on with the immune system. Most systems in the body have the decency to only include three or four types of cells, but the immune system just goes balls-out complicated. It’s like trying to keep track of the frigging Duggars, without the Amish gypsy vibe.

The “adaptive” (or “acquired”) immune response is pretty simple, though. Our bodies fight infection using what scientists call the “pissed-off soccer mom mechanism”.

Well. Some scientists call it that. A few. Probably.

Okay, only I call it that, and everyone else tells me to stop. But hear me out.

Think of your body as a bus, or an oversized minivan.

(This will be easier for some of us to visualize than others. Shaddup, skinnos.)

Now imagine the bus is parked at a Chuck E. Cheese’s, where soccer mom has driven to treat the team to an after-game meal. The kids have gone inside, wrought the unspeakable horrors that children inflict inside such establishments — hence the pissed-off soccer mom mechanism — and returned to the van for the ride home.

Before leaving, soccer mom has to take attendance. So she walks front to back, making sure all her kids are all accounted for — and checking for rogue children trying to sneak a free ride home. When she finds one — “Yo, there’s no ‘Salmonella’ on this roster sheet” — she doesn’t kick them off. No, no. The lady is frazzled after six hours of snot-wiping and animatronic idiot music; there’s no fight left in her. Soccer mom is a “dendrite cell”, merely recognizing the intruders. But she takes notes, and returns to the front of the bus.

And turns things over to soccer dad. He’s a “killer T cell”, and it’s his job to rid the bus of freeloaders. He’d rather be watching football, sure, but it was either this job or take the lymph nodes to ballet practice every weekend, so here he is. He takes soccer mom’s notes — the kids all look the same to him, otherwise — and drags the Streptococci and Smallpoxxes of the world off the bus and puts them back where they came from.

Namely, the inside of a Chuck E. Cheese’s.

That’s basically how adaptive immunity (and a kids’ soccer team outing) works: Mom sees a problem, tells Dad to take care of it and he makes a scene in the parking lot. It happened every Saturday during my childhood, and it’s happening in our bodies right now. The “pissed-off soccer mom mechanism” explains all — even special cases:

  • cancer immunology – Some kids on the team get rowdy and distract the driver.
  • autoimmune disease – Dad gets fed up and kicks everyone off the bus
  • immunodeficiency – The kids steal Mom’s notes, and the interlopers take over.

Take my advice: when it comes to immunology, just ask yourself, “If my mom had to put up with fourteen screaming kids all day and then got attacked by a germ, what would she do?” Works every time.

Actual Science:
iBiologyWhat is acquired immunity?
Nature ReviewsDendritic cells: controllers of adaptive immunity
Scripps Research InstituteThe Ultimate Decoy
ScienceAdaptive immunity goes back in time

Image sources: Cell (dendritic cell), ABGAb and Scientific American (cells ‘n’ Duggars), (angry mom), MomLogic (Chuck E. Diseases)

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