The Heart!

Hey guys!

This post is all about us! Or rather, it’s about the organ that allows us to do all the things we love to do. That’s right. The heart.

This is the most anatomically accurate picture I could find.

The heart is probably your most important organ. It pumps blood throughout your entire body which provides the rest of your organs with oxygen and nutrients that are necessary for them to function. Blood also carries away waste from those organs such as carbon dioxide (which then is transported to the lungs to be exhaled).

The heart works a lot like a sponge. There are special cells in the heart called pacemaker cells. These cells essentially send an electric jolt to the heart muscles that cause it to contract and wring the blood inside it out into the aortic valve, which leads to the aorta. The aorta is the largest artery in our body and is the entry way for blood to enter the rest of our veins.

After the heart is wrung out, it relaxes and the cells along the wall of the heart expand. This also relaxes the coronary vessels that rest on the outside of the heart. Once the muscle cells on the heart are relaxed, blood that was just ejected from the heart drips from the coronary vessels back into the heart to feed the muscle cells, which allows the heart to keep pumping. “Imagine clenching your fist sixty to seventy times per minute for your entire life, which is essentially what your heart does – without ever becoming exhausted” (Roizen and Oz. You: The Owners Manual. 33). 

Just kidding!

The heart is made up of four chambers. There are two atrium (think like an atrium in a house) and two ventricals. After blood has been circulated around the body, the oxygen that was in it has been used up by the various organs and muscles it visited. The blood is now “dirty” (or deoxygenated) and is circled back around to the heart. It is then returned to the right atrium which sends it into the right ventricle via the tricuspid valve. The right ventricle then send the “dirty” blood to the lungs via the pulmonary valve (the function of the valves is to keep blood from backtracking. If dirty and clean blood mixed, it would be much less effective at keeping our body working properly. The “heartbeat” that we hear is actually the valves slamming shut).

Once in the lungs, the blood takes the carbon dioxide which was given back to it by all the other organs and muscles and sends it out of the body (that’s why when we exhale, it is carbon dioxide that comes out). It then is infused with the oxygen that we just inhaled and sent back to the heart through the pulmonary vein and into the left atrium. The blood is then sent through the mitral valve into the left ventricle where it is squeezed back into the rest of the body via the aortic valve and the whole process starts over again.

-Sam

Citation list:

Roizen, Michael F., and Mehmet Oz. You: The Owner’s Manual. (New York: Collins, 2005), 32-51.

Wikipedia. “Blood.” Accessed May 4, 2013. http://en.wikipedia.org/wiki/Blood

Wikipedia. “Human heart.” Accessed May 4, 2013. http://en.wikipedia.org/wiki/Human_heart

Space and Time

Hey guys!

Sorry that it’s been forever since I posted. I started this post a couple weeks ago but hit a dead end trying to explain it, set it aside, then got busy with other things. This post was a tough one and I’m still doing my best to wrap my head around it but I thought it was incredibly interesting and trying to explain something is often the best way to understand it yourself. However, I  have no background in physics whatsoever and the purpose of this post is to make ideas accessible to everyday people so if I make any egregious technical errors or simplify a concept to much, please feel free to correct me in the comments.

This topic requires a little bit of background. Back in the days of the ancient Greeks, it was believed that the natural state for all things to be in was resting. Something only moved if it was pushed and, left to it’s own devices, it would go back to being still. This was the belief for a long, long time because no one ever really bothered to test if it was true or not.

This still makes me laugh

Eventually, Galileo did an experiment which showed that that was not the case and that when a force acts on an object, it’s effect is to speed it up or slow it down. Not just get it moving in the first place. When you push a ball, it does not stop on it’s own, but rather is stopped by friction on the ground and air resistance. If those and other external forces didn’t exist, it would continue to move forever. Newton expanded on that idea by publishing his laws of motion and gravity. For simplicity’s sake, I’m not going to recite them in this post but you can look them up here.

Newton’s laws have a lot of implications but the most important one for our purposes is that the idea of an absolute state of rest is incorrect. Common sense would lead us to believe that there is an absolute state of rest. Look at your chair or computer. It’s not moving and thus appears to be at rest. But while it looks like it’s just sitting there, it’s actually hurdling 67,000 mph (along with the rest of the planet) around the sun. And the sun is moving at it’s own breakneck speed around the center of the galaxy. So if you walk down the street at a brisk pace, are you walking at 5 mph or at 67,005 mph? Either one is technically correct and it demonstrates that the idea of space is relative, not absolute. Another example (shamelessly stolen from the book where I am getting most of my information, A Brief History of Time by Steven Hawking) is that of a train travelling north at 60 mph. Since the universe has no definitive boundaries, it would be equally correct to say that the earth is standing still and the train is moving north at 60 mph or that the train is standing still and the earth is moving down at 60 mph. Or both. 

This was a major milestone in understanding the universe, however people still thought of time as being absolute and unrelated to a “relative space”. Time marched forward, one second at a time and there was nothing anyone could do about it. However, people were still scratching their heads about something else: light. Did light have a constant speed? Well, in 1865, James Clerk Maxwell predicted that it did. So how fast does it go? The way that you determine speed is by dividing the distance it travels by the time it takes to get there. But space is not absolute, so no one could agree on how far it had traveled, even if they could agree on how long it took to get there.

Oh, Einstein, you.

In 1905, Albert Einstein, in a paper in response to this quandry, proposed his famous equation, E = mc^2. This essentially said that as an object goes faster, it gets heavier and thus requires more energy to propel it forward. Eventually, it will get to a point where it is infinitely heavy and requires an infinite amount of energy to move it and can not move any faster. However, since light has no mass, it can go faster then that speed (at 299,792,458 m/s to be exact) and nothing can move faster than light. This equation gave light a constant speed that was not affected by distance. To find the time it takes to get from one place to another, you divide the speed by the distance traveled. If no one can agree on the distance, since space is relative, it follows that no one can agree on the time it took to get there. This leads us to the conclusion that time is ALSO relative to the observer and is not a constant force which had been believed for thousands of years. This also integrated space and time so much that they can no longer be seen as separate and are now referred to as space-time.

I hope that that was a simple enough explanation. It’s hard to simplify it too much and still hit all the main points. Feel free to leave comments and let me know what you thought! Also, if you have any topics that you thought sounded interesting but were just too lazy to look up, let me know and I will try to get them explained for you!

-Sam

 Citation list:

Hawking, Stephen. A Brief History of Time. New York: Bantam, 1996

Wikipedia. “Newton’s Laws of Motion.” Accessed March 31, 2013. http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion

Curious about Astronomy? “At What Speed Does the Eath Move Around the Sun?” Accessed March 31, 2013. http://curious.astro.cornell.edu/question.php?number=356team

Wikipedia. “Mass-Energy Equivalence.” Accessed March 31, 2013. http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

Wikipedia. “Speed of Light.” Accessed March 31, 2013. http://en.wikipedia.org/wiki/Speed_of_light