29 June 2011

Miraculous muscle molecules

It’s been a while since I wrote a sciency post.  So let’s jump into it fast.  (Ironically, this is a long post.)

There is no way not to be awestruck at the speed and capabilities of the human (or any) body.  Examples of it are everywhere, and every one of them baffled me in school.  I still don’t fully comprehend them.  So let’s start with a simple demonstration, shall we?

Just so you can have this in mind as we go through the post, I want you to look down at your hand.  Either hand.  No, your dominant hand, let’s go with that one.  Now extend all your fingers out, just stretch your hand out wide.

Good.  Now as fast as you can, clench them into a fist.

Good!  Now fingers out, now fist.  Now go back and forth as fast as you can.  Faster!  Good.  Look at how fast that is, how many inches each fingertip is moving in the span of a few fractions of a second.

Okay, got it?  Like I said, just keep this in the back of your mind.

Today I want to talk about muscles.

My high school had an interesting approach to dissections and animal anatomy.  We learned about muscle connectivity using Tyson chicken wings (yes, the big bag of frozen ones you get at Costco).  If you hold up a chicken wing at its base (you know, where it used to meet the chicken) and then grab onto its little bicep and pull toward the absent chicken body, the whole wing will flap toward you.  Because the muscle is pulling the bone, right?  And that’s what muscles do, they contract and haul whatever they’re attached to along with them.  The muscles in your fingers are pulling them in toward your palm and out again.

But did you ever wonder how they do it?

I mean on a molecular level, what is pulling on what, exactly – what’s the machinery that makes it all contract like that?

It all comes down to two elements of a muscle cell: actin and myosin. 

(Before I get going about these two, we need a quick background.  Your body is made up of cells.  All kinds of cells.  All these cells contain thousands of types of proteins, which get to do all the action.  I always think of the proteins as the ants all running around doing things, while things like carbohydrates and fats make up the walls and food supply and stuff.  In fact – well, hopefully we’ve all heard of DNA here.  You know what DNA really is?  It’s a code for how to make proteins.  That’s it.  DNA tells your cell the exact recipe for every protein, and supplies information about where it goes and when to use it.  So proteins are the actors, the workers, the important molecules in a cell.  Okay, end background.)

So back to actin and myosin, which are both proteins.  Actin is a protein that, when put together with a bunch of other actin molecules, assembles into long filaments that help support the basic structure of a cell.  In a muscle fiber these filaments all run in parallel down the length of the muscle.

Myosin, on the other hand, is literally a little guy that walks along the actin filament.  (Okay, first off, how cool is that?  A protein – just a simple string of amino acids – can fold itself into a structure that looks like a pair of legs with big clubby Mickey Mouse feet!  That alone is mind-numbingly awesome.)

The myosin family of proteins. Figure borrowed from here. 

All right, I lied, there’s one other critical chemical in this story: adenosine triphosphate, or ATP.  ATP is an essential chemical in the body, it acts as an energy source.  Often when a protein needs energy, it just grabs onto an ATP molecule and rips off one of its three phosphates.  The breaking of this bond converts it from a triphosphate to a diphosphate (ADP) and produces the energy required to move.

So this is already a lot to take in, right?  Take a breather for a second and look down at your hand again.  Think about all the microscopic actin filaments and myosins and ATPs hanging out in there.  That’s right, this stuff is starting to get heavy.  Shall we continue?

So we have to get a little smaller than the muscle fiber level to see where actin and myosin come in.  Each muscle fiber is composed of a bundle of myofibrils, each of which consist of a string of sarcomeres.  It looks like this:

Figure borrowed from here

The sarcomeres are units of overlapping thick and thin filaments – the thin filaments are made of actin attached to each end of the sarcomeres, and the thick filaments are made up of a bunch of myosins all strung together, sitting in the middle of the sarcomere.

When the muscle contracts, here’s what happens.

1.       We’ll start with the myosin floating above the actin filament, with an ATP molecule bound to it.  The ATP separates into ADP and a phosphate, which shoves the myosin’s little foot (scientists call it a head – go figure) forward.

2.       When the myosin head gets close to the actin, the phosphate is released (leaving ADP behind) and the myosin head binds tightly onto the actin filament and yanks it backward. 

3.       The myosin releases the ADP and another ATP comes in to take its place.  When ATP binds in there, the myosin releases its hold on the actin filament.

4.       The ATP converts to ADP and a phosphate, the myosin head cocks forward, and the process starts all over again.

If I have just befuddled you beyond comprehension, go here and look at this fantastical video.

Also, keep in mind that all of these steps are nothing more than the probabilistic functions of a bunch of molecules lounging around in a cellular soup – they’re just events that are likely to happen.  It’s not like these are the directed, intentional acts of a bunch of conscious little players, in other words.  No.  This is just… chemistry.

But here’s the real point.  Do you see how long it took me to explain this?  Do you see that the video to which I directed you took a full thirty seconds just to show you a detailed depiction of a single pull of a myosin head on an actin filament? 

Now go back and look at your hand.  Flex it a couple of times again, fast.  Every single time you twitch a muscle anywhere in your body, thousands of ATP molecules are being used up to allow thousands of little myosins to pull many times over on thousands of actin filaments.  And somehow they can do it that fast and still be ready for another pull an instant later! 

How can anyone reconcile this?  How on Earth can it work this way?  It’s crazy.

Next post: the magnificent neuronal synapse.

28 June 2011

Breathe Here Now

Whenever I go down the hall at work I see this sign.  It says,

Breathe Here Now.

It goes on to say more, it’s a Campus Health sign aimed to promote taking calming breaths to relieve college-life stress.  But every time I see it I have to pause and contemplate just that little phrase, the title.  What a beautiful message, eh?




27 June 2011

Pickles yes, toothpaste no.

Get ready – I’m going to broaden your culinary world. 

I’m not much into mixing things up, and the recipes I’ve tried are by no means radical.  But I think when someone hits upon a fantastic heretofore unconsidered flavor combination, it should not go without note.  Here are some inventions I have given my seal of approval… and for good measure, also some that induced nausea or vomiting.  Consider it a fair warning.

Cinnamon Toast Crunch and Golden Grahams – Approved!
Being the grownup that I am, I eat as much sugary kids’ cereal as I want.  Being the actual grownup that I am, I am very careful to meter my sugary cereal intake.  So when I splurged and bought both boxes of my two favorite cereals at once, it was game on.  And CTC&GG is, in a word, divine.  It’s like Teddy Grahams, have you ever eaten Teddy Grahams?  Well, it’s like that, only more.  I don’t know that I can ever go back to either solo again.

Nerds and Oreos – Approved!
I don’t mean nerds as in geeky or dorky people (I know those three terms have strict and unique operational definitions, get over it!) – I mean Nerds like the candy.  Nerds are very tangy sugar candies, and in the right proportions they are the perfect complement to Oreos in a Dairy Queen blizzard.  No, really.  I used to work at a Dairy Queen so I know these things.  And when it comes to blizzards, I’ve tried it all.  I gained some serious heft in the few months I worked there.  So I know.  Trust me.  Oreo-and-Nerds blizzards are right up there with my other most recent favorite, Oreo-Reese’s-Cookie Dough-Heath blizzards.  The key with a blizzard is to order a whole load of different candy types because, like I said earlier, I am an adult and that means a lot of puritanical abstinence followed by gluttonous binges on things I can now have any damn time I want, thank you.

(UPDATE Nov 2011: Apparently Dairy Queen has stopped carrying Nerds! Oh, the humanity! How will anyone know now just how very right I am about this?!)

Coke and pickle juice – Approved!
I bet you thought I was going to label this one nausea/vomiting.  No one ever believes me when I say this is good.  But it is.  I should probably say ‘any cola-flavored beverage’ to minimize any lawsuits over singling out Coke, so pretend I said that first.  With the Any Cola-Flavored Beverage and Pickle Juice recipe, the ratio is key: a couple of tablespoons of pickle juice per 12-oz. can is perfect.  It just gives a little sour savory kick to the corny syrupy-sweetness of the cola.

Toothpaste and anything else – Nasty
I don’t have to explain this one, everyone knows it.  I just wanted to point it out.  There’s nothing more heartbreaking than brushing your teeth right before a delicious morning meal.  Especially one with orange juice.

I do want to mention one particular combination of note, here – toothpaste and peppermint schnapps.  This almost sounds like a good idea, because they’re both minty, right?  Wrong.  It is hideous and disgusting.  Do not attempt.

Savory oatmeal – Nausea-Inducing
I have already said it in this blog – oatmeal is not risotto.  It is not. risotto.  And it only made it worse to have that well-meaning analogy running through my head when I tried to make a dinner meal out of oatmeal, tomatoes, basil and garlic.  Do not try this.  You will not want to eat anything ever again as long as you live.

Coke, lemon juice, hot sauce, toothpaste, etc. – Actual Vomiting Inevitable
Kids are evil, malevolent creatures, and so were we.  This suicide drink was not a very nice dare for Truth or Dare, and somehow we got not one but two kids to drink it.  Both ended up hurling almost instantaneously on contact, and the rest of us suffered the remainder of the evening trying not to breathe in the fumes from that horrid concoction for fear of succumbing to a similar fate.

Okay, I’m grossing myself out with the memory.  I’d better leave it there.  So, take home lesson: When it comes to food, try anything once.  As long as it doesn’t involve toothpaste.

09 June 2011

Unfinished business

I know some of you might think I’m neglecting you, so I thought I’d show you some of the things I’m neglecting even more in the hope of making you feel better.

Laundry: 3 weeks +

This is my laundry hamper.  You can almost see it under the pile of extra clothes that won’t fit in it. 

Some people in the know might note that the pink-ribboned garment was last worn more than a month ago.  Under that, those sheets are going on two or three months now.  (In fairness to me, those are both things that were hiding in suitcases that I had not, until last week, unpacked.  Okay, that doesn’t really help my case.  But I did unpack them!  Eventually!)

Also, this is my bed:

You can’t tell it’s my bed because of all the clean clothes on it that have yet to be folded and put away.  This pile makes a daily commute from my desk chair to my bed and back again.

Yoga: 2 months

I’m supposed to be going to yoga a few times weekly.  I’ve gone once since April.

Stargate: 5 months

This is our Stargate. 

I am supposed to make a DHD for it (a DHD is a Dial Home Device, for those who aren’t nerds).  I’m also supposed to make the Stargate move (or make another one that moves).  Also, the background shows evidence of a filthy floor that needs cleaning as well.

I just want to mention that if we do get our Stargate to move, husband may or may not create an app that allows you to dial in to our Stargate remotely.  How cool is that?

Lights: 6 months

I was going to show you a picture of our Christmas lights, but realized husband would not appreciate me showing our front door to the whole internet.  But our Christmas lights are up outside.  ’Nuff said.

(Although… in only two short weeks they’ll be up six months early!  Score!)

Reading: 6 months +

Here is a pile of books (there is another pile behind it) that I received for Christmas and have not yet read.  (I did at least finish one [not pictured]).  These are only the ones I got last Christmas.  I have plenty more on my shelves I haven’t read.

I'd also like to direct your attention to three fabulous books on the left, there: Naked Lunch, Lolita, and the aforementioned Catch-22.

Earrings: 9 months

My sister and I got it in our heads to start making our own earrings.  I made one pair and you can see what happened to the rest.

Paintings: 2 years

These are two of my unfinished paintings.

I don’t know that I’ve ever finished a painting I’ve started.  I started the first of these two in 2007 and the other in 2008 or 2009.  The first one is a picture of the Marina Grande in Sorrento, Italy, and there is supposed to be a cat in front of it. Here is a poor practice run at the sad little kitty.

So there you have it, some of the many things I’m conspicuously not doing.  And these are by no means my longest stretches.  I debated whether to put more things on this list but by the time you get out this far temporally, the things you’re delaying on are either things you really don’t need to finish anymore or things that are personal and kind of tragic.  So I think I’ll leave those alone.

But you can at least see that this blog is by no means my most neglected pursuit.  Keep that in mind whenever you feel I’m falling behind.